ORCID Profile
0000-0001-7328-4831
Current Organisation
University of Technology Sydney
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Infectious Agents | Medical Parasitology | Veterinary Parasitology | Medical Microbiology | Gastroenterology And Hepatology | Soil Sciences | Microbiology | Freshwater Ecology | Infectious Diseases | Soil And Water Sciences Not Elsewhere Classified | Conservation And Biodiversity |
ANZSRC Socio-Economic Objective (SEO)
Living resources (flora and fauna) | Land and water management | Digestive system and disorders | Infectious diseases | Expanding Knowledge in the Agricultural and Veterinary Sciences | Veterinary Biological Preventatives (e.g. Vaccines) | Expanding Knowledge in the Biological Sciences | Diagnostic methods
Related Links
Publications
The Leishmania major RNA polymerase II largest subunit lacks a carboxy-terminus heptad repeat structure and its encoding gene is linked with the calreticulin gene.
Publisher: Elsevier BV
Date: 05-2000
Abstract: The gene encoding the RNA polymerase II largest subunit (RPOIILS) has been isolated and sequenced from the kinetoplastid protozoan, Leishmania (Leishmania) major. The RPOIILS gene was shown to be present as a single copy and is composed of an uninterrupted open reading frame of 4.99 kb, specifying a protein 1663 aa in length with a predicted molecular mass of approximately 185 kDa. The carboxy terminus domain (CTD) of the RPOIILS from L. (L.) major, typical of the more evolutionary primitive protozoa, lacked a heptad repeat structure which is present in higher eukaryotes and some other protozoan phyla. Comparison of the predicted aa composition of the CTD from a erse range of eukaryotic species revealed the abundance of Ser and Pro residues as the only discernible evolutionary conservative feature. A putative ATG start codon for an additional expressed sequence was located 1.1 kb downstream of the L. (L.) major RPOIILS gene stop codon. Nucleic acid database searches revealed the identity of this gene as that encoding the calcium binding protein calreticulin (CLT). The close proximity of the RPOIILS and CLT genes in L. (L.) major raises the possibility that these genes are transcribed as part of the same polycistronic unit.
Comparison Of The Large Subunit Ribosomal DNA Of Neospora And Toxoplasma And Development Of A New Genetic Marker For Their Differentiation Based On The D2 Domain
Publisher: Elsevier BV
Date: 02-1998
Abstract: The latest release of the large subunit ribosomal database contains 429 sequences, yet only 10 (six nuclear and four mitochondrial) are derived from parasites of the phylum Apicomplexa. Three of these (all Toxoplasma gondii) were previously contained in the 1994 release of the database. As an initiative towards an understanding of ribosomal gene organization in the Apicomplexa, the primary sequence of the large subunit (LSU) rDNA of Neospora caninum is presented, and compared with a consensus sequence derived for the LSU rDNA of T. gondii. Nucleotide differences observed between these two taxa in the D2 expansion segment (or domain) (also called the C1/C1' region) of the LSU rDNA were incorporated into a primer that forms the basis of a species-specific polymerase chain reaction (PCR) for N. caninum. The D2 domain of the LSU rDNA, therefore, represents a new genetic marker that can be used for the differentiation and identification of Neospora from other cyst-forming coccidia.
Development of a genetically engineered vaccine against poultry coccidiosis.
Publisher: Elsevier BV
Date: 1991
DOI: 10.1016/0169-4758(91)90216-B
Abstract: Coccidiosis is caused by infection with Eimeria spp. The disease is responsible for major economic loss to the poultry industry unless infections are controlled by anticoccidial drugs. John Ellis and Fiona Tomley discuss recent research on the characterization and cloning of antigens from Eimeria spp and advances towards the development of genetically engineered vaccines against poultry coccidiosis.
Immunization of cattle with live tachyzoites of Neospora caninum confers protection against fetal death
Publisher: American Society for Microbiology
Date: 03-2007
DOI: 10.1128/IAI.00777-06
Abstract: Neospora caninum is an obligate intracellular protozoan parasite that causes abortion in cattle. It is normally found as a latent infection controlled by a T-helper-cell type 1 response involving CD4 + cytotoxic T cells and gamma interferon. Cattle may be infected by two different routes: transplacentally as a result of activation of the latent infection in the mother causing congenital infection or abortion and by ingestion of oocysts, which, if it occurs during gestation, can also result in abortion. Here, for the first time, we establish proof that live vaccination protects against fetal death, whereas immunization using whole-tachyzoite lysate in different adjuvants fails to protect against fetal death. Strong antibody responses were induced in all the vaccinated groups, and the quality and magnitude of these responses were similar in the live- and the lysate-vaccinated groups. In contrast, only the group immunized with live tachyzoites had strong cellular and gamma interferon responses prior to challenge, and these responses correlated with protection against fetopathy. These results suggest that a cellular immune response may be important in the mechanisms involved in protection against N. caninum -associated abortions.
Prevalence of Neospora caninum infection in Australian (NSW) dairy cattle estimated by a newly validated ELISA for milk
Publisher: Elsevier BV
Date: 11-2006
DOI: 10.1016/J.VETPAR.2006.06.019
Abstract: To determine the performance characteristics of an Institut Pourquier (IP) enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies against Neospora caninum in bovine milk and subsequent determination of the prevalence of N. caninum infection in New South Wales (NSW) dairy cattle. Matching serum and milk s les from 93 cattle were assayed in two commercially available ELISAs for the detection of anti-N. caninum antibodies. Serum test results of one ELISA (IDEXX) were used to determine the N. caninum infection status of the cattle. Optimised cut-off values for the IP ELISA using milk s les were determined by two-graph receiver operating characteristic (TG-ROC) analysis and then applied to a representative s le of 398 milk s les from dairy herds around NSW. When this ELISA was applied to a representative collection of 398 milk s les from dairy cattle across NSW it demonstrated a 21.1% prevalence of N. caninum infection in those cattle. From the TG-ROC analysis an IP ELISA protocol was derived which suggested a cut-off threshold that would allow milk testing with 97% sensitivity and specificity, respectively, relative to serum testing. The prevalence of N. caninum in NSW dairy cattle was higher than previously believed. When used on in idual milk s les this ELISA demonstrated high sensitivity and specificity and so could be used to accurately identify N. caninum infection. TG-ROC analysis of the IP ELISA optimised the protocol and prescribed cut-off values enabling the ELISA to be used for the screening of N. caninum antibodies in the milk of dairy cattle.
In vitro susceptibility testing of Dientamoeba fragilis
Publisher: American Society for Microbiology
Date: 2012
DOI: 10.1128/AAC.05125-11
Abstract: Dientamoeba fragilis is a commonly encountered trichomonad which has been implicated as a cause of gastrointestinal disease in humans. Despite the frequency of reports recording infections with this parasite, little research has been undertaken in terms of antimicrobial susceptibility. The aim of this study was to evaluate the susceptibility of D. fragilis to several commonly used antiparasitic agents: diloxanide furoate, furazolidone, iodoquinol, metronidazole, nitazoxanide, ornidazole, paromomycin, secnidazole, ronidazole, tetracycline, and tinidazole. Antibiotic susceptibility testing was performed on four clinical strains of D. fragilis , designated A, E, M, and V, respectively. Molecular testing followed, and all strains were determined to be genotype 1. The activities of antiprotozoal compounds at concentrations ranging from 2 μg/ml to 500 μg/ml were determined via cell counts of D. fragilis trophozoites grown in dixenic culture. Minimum lethal concentrations (MLCs) were as follows: ornidazole, 8 to 16 μg/ml ronidazole, 8 to 16 μg/ml tinidazole, 31 μg/ml metronidazole, 31 μg/ml secnidazole, 31 to 63 μg/ml nitazoxanide, 63 μg/ml tetracycline, 250 μg/ml furazolidone, 250 to 500 μg/ml iodoquinol, 500 μg/ml paromomycin, 500 μg/ml and diloxanide furoate, μg/ml. This is the first study to report the profiles of susceptibility to a wide range of commonly used treatments for clinical isolates of D. fragilis . Our study indicated 5-nitroimidazole derivatives to be the most active compounds in vitro against D. fragilis .
The cell-mediated immune response to Neospora caninum during pregnancy in the mouse is associated with a bias towards production of interleukin-4
Publisher: Elsevier BV
Date: 05-2004
Dientamoebiasis: clinical importance and recent advances
Publisher: Elsevier BV
Date: 02-2006
Abstract: Dientamoeba fragilis, an unusual single-celled parasite that was described first in 1918, is found worldwide in the gastrointestinal tract of humans. D. fragilis has emerged from obscurity recently because it is now recognized as a common cause of chronic diarrhoea and is treatable with drugs. Recent molecular studies have described D. fragilis as having two genotypes. Diagnostic tests, based on conventional and real-time PCR, have been developed that will provide a rapid, sensitive and specific diagnosis of D. fragilis. These tests will also aid the elucidation of the host distribution and the life cycle of this pathogen.
30 years of parasitology research analysed by text mining
Publisher: Cambridge University Press (CUP)
Date: 09-2020
DOI: 10.1017/S0031182020001596
Abstract: Bibliometric methods were used to analyse the major research trends, themes and topics over the last 30 years in the parasitology discipline. The tools used were SciMAT, VOSviewer and SWIFT-Review in conjunction with the parasitology literature contained in the MEDLINE, Web of Science, Scopus and Dimensions databases. The analyses show that the major research themes are dynamic and continually changing with time, although some themes identified based on keywords such as malaria, nematode, epidemiology and phylogeny are consistently referenced over time. We note the major impact of countries like Brazil has had on the literature of parasitology research. The increase in recent times of research productivity on ‘antiparasitics’ is discussed, as well as the change in emphasis on different antiparasitic drugs and insecticides over time. In summary, innovation in parasitology is global, extensive, multidisciplinary, constantly evolving and closely aligned with the availability of technology.
Control options for Neospora caninum infections in cattle - Current state of knowledge
Publisher: Informa UK Limited
Date: 06-2002
DOI: 10.1080/00480169.2002.36288
Abstract: This article reviews control options for Neospora caninum infection and abortion in cattle, drawing on published literature and the authors' own research in this field. Apart from the successful use of embryo transfer to prevent congenital infection in calves born to infected cows, there are currently no accepted control methods for the prevention of abortions in cattle. The epidemiological data at hand suggest that concomitant infections with bovine pestivirus increase the risk of abortion significantly and that these infections, for which effective vaccines exist, should therefore be controlled. While vertical transmission appears to be the major route of infection in cattle, there is also a role for postnatal transmission, involving a definitive host. Presently, the control of dogs and their access to bovine tissues, particularly potentially infected placentae and other foetal tissues, appear to be the most prudent control methods. There are some indications that vaccination against N. caninum may aid in the prevention of abortions. Suggestions for control options are limited by our current lack of actual experiences with control strategies. Further practical fieldwork is needed in this area.
Characterisation of a simple, highly repetitive DNA sequence from the parasite Leishmania donovani
Publisher: Elsevier BV
Date: 05-1988
DOI: 10.1016/0166-6851(88)90114-4
Abstract: Repetitive DNA sequences of the Leishmania donovani genome have been identified by screening a recombinant DNA library made by cloning sheared genomic DNA into the vector pAT153. Bacterial clones containing a highly repetitive DNA sequence have been isolated. DNA sequencing has shown that this sequence is composed of tandem repeats of the sequence 5'-CCCTAA-3'. This sequence is identical to the telomeric repeats found in Trypanosoma brucei and hybridizes to all Leishmania chromosomes. In this study we show that there is considerable heterogeneity in the distribution and copy number of this repeat and associated hybridising sequences throughout the genomes of different Leishmania species.
A state-of-the-art methodology for high-throughput in silico vaccine discovery against protozoan parasites and exemplified with discovered candidates for Toxoplasma gondii.
Publisher: Springer Science and Business Media LLC
Date: 22-05-2023
DOI: 10.1038/S41598-023-34863-9
Abstract: Vaccine discovery against eukaryotic parasites is not trivial as highlighted by the limited number of known vaccines compared to the number of protozoal diseases that need one. Only three of 17 priority diseases have commercial vaccines. Live and attenuated vaccines have proved to be more effective than subunit vaccines but adversely pose more unacceptable risks. One promising approach for subunit vaccines is in silico vaccine discovery, which predicts protein vaccine candidates given thousands of target organism protein sequences. This approach, nonetheless, is an overarching concept with no standardised guidebook on implementation. No known subunit vaccines against protozoan parasites exist as a result of this approach, and consequently none to emulate. The study goal was to combine current in silico discovery knowledge specific to protozoan parasites and develop a workflow representing a state-of-the-art approach. This approach reflectively integrates a parasite’s biology, a host's immune system defences, and importantly, bioinformatics programs needed to predict vaccine candidates. To demonstrate the workflow effectiveness, every Toxoplasma gondii protein was ranked in its capacity to provide long-term protective immunity. Although testing in animal models is required to validate these predictions, most of the top ranked candidates are supported by publications reinforcing our confidence in the approach.
Research into Neospora caninum—What Have We Learnt in the Last Thirty Years?
Publisher: MDPI AG
Date: 23-06-2020
Abstract: Background: Neospora caninum has been recognised world-wide, first as a disease of dogs, then as an important cause of abortions in cattle for the past thirty years. Over that time period, there have been improvements in the diagnosis of infection and abortion, new tests have been developed and validated, and it is timely to review progress to date. Methods: Bibliometric methods were used to identify major trends and research topics present in the published literature on N. caninum. The tools used were SWIFT-Review, VOSviewer and SciMAT, along with the published papers found in the MEDLINE, Dimensions and Web of Science databases. A systematic review of the published Neospora literature (n = 2933) was also carried out via MEDLINE and systematically appraised for publications relevant to the pathogenesis, pathology and diagnosis of Neospora abortions. Results: A total of 92 publications were included in the final analysis and grouped into four main time periods. In these four different time periods, the main research themes were “dogs”, “abortion”, “seroprevalence” and “infection”. Diagnostics, including PCR, dominated the first two time periods, with an increased focus on transmission and abortions, and its risk factors in cattle. Conclusions: Longitudinal analyses indicated that the main themes were consistently investigated over the last 30 years through a wide range of studies, with evolving emphasis initially on dogs and diagnostic test development, followed by application to cattle, the identification of the risk factors leading to abortion, and in the latter time periods, an understanding of the immunity and a search for vaccines.
The Prevalence of Angiostrongylus cantonensis/mackerrasae Complex in Molluscs from the Sydney Region.
Publisher: Public Library of Science (PLoS)
Date: 22-05-2015
Naturally acquired immunity to malaria
Publisher: Cambridge University Press (CUP)
Date: 08-01-2016
Epidemiology and geographical distribution of enteric protozoan infections in Sydney, Australia
Publisher: SAGE Publications
Date: 02-07-2014
Abstract: Enteric protozoa are associated with diarrhoeal illnesses in humans however there are no recent studies on their epidemiology and geographical distribution in Australia. This study describes the epidemiology of enteric protozoa in the state of New South Wales and incorporates spatial analysis to describe their distribution. Laboratory and clinical records from four public hospitals in Sydney for 910 patients, who tested positive for enteric protozoa over the period January 2007 - December 2010, were identified, examined and analysed. We selected 580 cases which had residence post code data available, enabling us to examine the geographic distribution of patients, and reviewed the clinical data of 252 patients to examine possible links between protozoa, demographic and clinical features. Frequently detected protozoa were Blastocystis spp. (57%), Giardia intestinalis (27%) and Dientamoeba fragilis (12%). The age distribution showed that the prevalence of protozoa decreased with age up to 24 years but increasing with age from 25 years onwards. The geographic provenance of the patients indicates that the majority of cases of Blastocystis (53.1%) are clustered in and around the Sydney City Business District, while pockets of giardiasis were identified in regional/rural areas. The distribution of cases suggests higher risk of protozoan infection may exist for some communities. These findings provide useful information for policy makers to design and tailor interventions to target high risk communities. Follow-up investigation into the risk factors for giardiasis in regional/rural areas is needed.
The evolution of trypanosomatid taxonomy
Publisher: Springer Science and Business Media LLC
Date: 08-06-2017
If control of Neospora caninum infection is technically feasible does it make economic sense?
Publisher: Elsevier BV
Date: 11-2006
DOI: 10.1016/J.VETPAR.2006.06.027
Abstract: Recent work on Neospora caninum, a protozoan parasite that causes abortions in dairy cattle has focused on a number of different control options. Modelling has suggested the most effective options for control but the present paper argues that the most effective option might not necessarily be optimal from an economic point of view. Decision trees, using published quantitative data, were constructed to choose between four different control strategies. The costs of these interventions, such as 'test and cull', therapeutic treatment with a pharmaceutical, vaccination or "doing nothing" were compared, and modelled, in the first instance, on the New Zealand and Australian dairy situation. It is argued however, that the relative costs in other countries might be similar and that only the availability of a registered vaccine will change the decision tree outcomes, as does the within-herd prevalence of N. caninum infection. To "do nothing" emerged as the optimal economic choice for N. caninum infections/abortions up to a within-herd prevalence of 18%, when viewed over a 1-year horizon, or 21% when costs were calculated over a 5 years horizon. For a higher (>or=21%) within-herd prevalence of N. caninum infection vaccination provided the best (i.e. most economic) strategy. Despite being the most efficacious solutions, 'test and cull' or therapeutic treatment never provided a viable economic alternative to vaccination or "doing nothing". Decision tree analysis thus provided clear outcomes in terms of economically optimal strategies. The same approach is likely to be applicable to other countries and the beef industry, with only minor changes expected in the relationships of decisions versus within-herd prevalence of N. caninum infection.
Repeated Dientamoeba fragilis infections: a case report of two families from Sydney, Australia
Publisher: MDPI AG
Date: 14-09-2009
DOI: 10.4081/IDR.2009.E4
Staged heterogeneity learning to identify conformational B-cell epitopes from antigen sequences
Publisher: Springer Science and Business Media LLC
Date: 03-2017
Comparison of Microscopy, Culture, and Conventional Polymerase Chain Reaction for Detection of Blastocystis sp. in Clinical Stool Samples.
Publisher: American Society of Tropical Medicine and Hygiene
Date: 04-02-2011
Attachment and invasion of Toxoplasma gondii and Neospora caninum to epithelial and fibroblast cell lines in vitro
Publisher: Cambridge University Press (CUP)
Date: 11-07-2005
DOI: 10.1017/S0031182005008310
Abstract: Attachment and invasion of Toxoplasma gondii and Neospora caninum to a cat and a dog fibroblast cell line and 2 epithelial cell lines (a cat kidney and Vero) were compared in vitro using fluorescence antibody methodology. In addition, trypsin treatment of tachyzoites was used to determine whether protein molecules were essential to the process of invasion. The results show that both T. gondii and N. caninum invaded all 4 cell lines, and that pre-treatment of T. gondii tachyzoites with trypsin caused an increase in the ability of the parasite to invade these host cells. Furthermore T. gondii , in comparison to N. caninum , invaded all 4 cell lines at greater levels. The results here support the conclusion that both T. gondii and N. caninum have the ability to invade a variety of cell types including both dog and cat cells, and questions the utility of Vero cells as an appropriate host cell for in vitro studies on the biology of these taxa.
Evolution of the genus Leishmania revealed by comparison of DNA and RNA polymerase gene sequences
Publisher: Elsevier BV
Date: 11-1997
DOI: 10.1016/S0166-6851(97)00111-4
Abstract: Previous hypotheses of Leishmania evolution are undermined by limitations in the phylogenetic reconstruction method employed or due to the omission of key parasites. In this experiment, sequences of the gene encoding the DNA polymerase alpha catalytic polypeptide (POLA) were analysed phylogenetically in combination with those encoding the RNA polymerase II largest subunit gene (RPOIILS) to infer a comprehensive phylogeny of Leishmania. Nineteen species of parasites were studied, comprising representatives of each Leishmania species-complex (Leishmania Leishmania tropica, Leishmania Leishmania donovani, Leishmania Leishmania mexicana, Leishmania Leishmania hertigi and Leishmania Viannia braziliensis), as well as parasites of questionable taxonomy (Leishmania herreri, Sauroleishmania adleri, Sauroleishmania deanei, Sauroleishmania gymnodactyli and Sauroleishmania tarentolae). The analyses presented here provide strong support for the hypothesis that the Leishmania that infect reptiles (also known as Sauroleishmania) evolved from mammalian Leishmania. One implication of this finding is that the taxonomic definition of Leishmania should be broadened to encompass characteristics of the reptilian parasites. However, this taxonomic revision is complicated in that Leishmania (L.) hertigi, Leishmania (L.) deanei and Leishmania herreri, which exhibit some biological properties of Leishmania, are more closely related to Endotrypanum on the basis of these sequence comparisons. Consequently, the taxonomic discrimination between Leishmania that infect mammals, Leishmania that infect reptiles and Endotrypanum may be more problematic than has been previously thought. Since our resulting phylogenetic hypothesis is supported by the analyses of two different genes, we speculate on the origin and evolutionary expansion of this lineage of kinetoplastid protozoa.
Ribosomal DNA Spacer Genotypes of the Anopheles Bancroftii Group (Diptera: Culicidae) from Australia and Papua New Guinea
Publisher: Wiley
Date: 10-2001
DOI: 10.1046/J.0962-1075.2001.00278.X
Abstract: Mosquitoes of the Anopheles bancroftii group collected from Northern Australia and Papua New Guinea (PNG) were investigated for sequence variation within the ribosomal DNA ITS2. Wing fringe morphology originally used to identify members of this group was compared to genotypes identified by restriction fragment length polymorphism analysis (RFLP) and heteroduplex analysis (HDA) of the rDNA ITS2. Members of this group separated into four RFLP genotypes (A, B, C and D) with some genotypes displaying wing fringe polymorphisms. Heteroduplex analysis of the ITS2 within and between populations identified genotype A as containing two geographically separate ITS2 sequences: A1 from the Northern Territory of Australia and A2 from Queensland and the Western Province of PNG. Genotypes B and C and genotypes C and D were found sympatric and appeared to be evolving independently suggesting the possibility of cryptic species. Genotype C contained two ITS2 sequence types within the genome.
Characterisation of the first Australian isolate of Neospora caninum from cattle
Publisher: Wiley
Date: 10-2002
DOI: 10.1111/J.1751-0813.2002.TB10967.X
Abstract: To isolate Neospora caninum from a congenitally infected calf. A calf was obtained from a N. caninum infected dam maintained in a dairy herd of Holstein-Friesian cattle located on the south coast of NSW near Nowra. The calf was euthanased and s les collected for serology and pathology. S les of brain and spinal cord of the calf were homogenised and injected into immunocompromised mice in an attempt to recover protozoa by in vivo culture. Sequential passage of brain homogenate through IFNgammaPKO mice was performed and tissue culture flasks were inoculated with brain homogenate. Parasites were identified by electron microscopy and DNA sequencing. The antigen profile of the isolate was analysed using Western blotting. Pathogenicity was examined in BALB/c mice and transmission of the parasite during pregnancy was examined in Qs mice. The calf was seropositive for N. caninum and histopathological examination of sections of cerebrum identified lesions consistent with a very mild infection with N. caninum. The parasites isolated using tissue culture were identified as N. caninum, based on the sequence of the ribosomal DNA and electron microscopy. The antigen profile of the new isolate was similar to that of the NC-Liverpool isolate, but quite different from that of Toxoplasma gondii. In BALB/c mice inoculated with the new isolate, severe clinical signs developed in only three of ten infected mice, compared with six of ten mice infected with NC-Liverpool. Mild to moderate nonsuppurative encephalitis was observed in BALB/c mice infected with the new isolate, compared with mice infected with NC-Liverpool, that developed severe nonsuppurative encephalitis. Transplacental transmission of the isolate arising from an acute infection during pregnancy occurred in about 87% of pups. This is the first isolation of bovine Neospora caninum in Australia. This isolate, called NC-Nowra, appears to be a less virulent form and may prove to be a suitable candidate for vaccine development.
Analysis of dinucleotide frequency and codon usage in the phylum Apicomplexa.
Publisher: Elsevier BV
Date: 04-1993
DOI: 10.1016/0378-1119(93)90363-8
Abstract: Dinucleotide frequency (DiF) and codon usage (cu) were analysed in gene sequences from four parasitic protozoa, Babesia bovis, Theileria parva, Toxoplasma gondii and Eimeria tenella, of the phylum Apicomplexa. In keeping with the 'genome hypothesis', cu was found to be non-random and species specific in these organisms, although cu among members of the same subclass was found to be very similar. Several low-usage (lu) codons were identified, and the usage of lu codons appears to be related to the taxonomic position of the organisms under study. A comparison of the observed/expected DiF ratios obtained from gene coding regions revealed a low frequency of the TA and CG dinucleotides in all organisms studied. A comparison of these DiF ratios with those found in rRNA-encoding genes and in introns, showed that in the parasites, B. bovis and Th. parva (representing the piroplasms), the low frequency of dinucleotides appeared to be the result of coding pressure alone. In T. gondii and E. tenella (representing the coccidia), however, coding pressure could not completely explain differences in DiF.
A review of the infection, genetics, and evolution of Neospora caninum: From the past to the present
Publisher: Elsevier BV
Date: 2013
DOI: 10.1016/J.MEEGID.2012.08.012
Abstract: This paper is a review of current knowledge on Neospora caninum in the context of other apicomplexan parasites and with an emphasis on: life cycle, disease, epidemiology, immunity, control and treatment, evolution, genomes, and biological databases and web resources. N. caninum is an obligate, intracellular, coccidian, protozoan parasite of the phylum Apicomplexa. Infection can cause the clinical disease neosporosis, which most notably is associated with abortion in cattle. These abortions are a major root cause of economic loss to both the dairy and beef industries worldwide. N. caninum has been detected in every country in which a study has been specifically conducted to detect this parasite in cattle. The major mode of transmission in cattle is transplacental (or vertical) transmission and several elements of the N. caninum life cycle are yet to be studied in detail. The outcome of an infection is inextricably linked to the precise timing of the infection coupled with the status of the immune system of the dam and foetus. There is no community consensus as to whether it is the dam's pro-inflammatory cytotoxic response to tachyzoites that kills the foetus or the tachyzoites themselves. From economic analysis the most cost-effective approach to control neosporosis is a vaccine. The perfect vaccine would protect against both infection and the clinical disease, and this implies a vaccine is needed that can induce a non-foetopathic cell mediated immunity response. Researchers are beginning to capitalise on the vast potential of -omics data (e.g. genomes, transcriptomes, and proteomes) to further our understanding of pathogens but especially to identify vaccine and drug targets. The recent publication of a genome for N. caninum offers vast opportunities in these areas.
A Biochemical Protocol For The Differentiation Of Current Genomospecies Of Aeromonas
Publisher: Elsevier BV
Date: 06-1996
DOI: 10.1016/S0934-8840(96)80151-4
Abstract: A data file consisting of 40 biochemical and physiological tests for the differentiation of aeromonads was constructed based upon existing published data from various geographical locations and laboratories. The data file covers all the current genomospecies (or hybridisation groups) of Aeromonas and is therefore applicable to bacteriologists from a wide variety of fields. The protocol derived from the data file was adapted for use with a semi-interactive computer identification program. This program was challenged with the type strains of all the currently recognised genomospecies and each genomospecies was correctly identified, with only one strain (ATCC 7966, HG1) having an identification probability of less than 90%. The program was also tested with environmental and clinical isolates and again identifications were achieved with high probabilities. This protocol is designed for use on presumptive isolates of Aeromonas spp. and can be carried out in routine laboratories not equipped to perform the complex DNA hybridisation techniques which are currently used for the differentiation of genomospecies of Aeromonas.
Gastrointestinal pathogen distribution in symptomatic children in Sydney, Australia
Publisher: Springer Science and Business Media LLC
Date: 2013
Thioredoxins of a parasitic nematode: Comparison of the 16- and 12-kDA thioredoxins from Haemonchus contortus
Publisher: Elsevier BV
Date: 06-2008
DOI: 10.1016/J.FREERADBIOMED.2008.03.007
Abstract: Thioredoxins are a family of small proteins conserved through evolution, which are essential for the maintenance of cellular homeostasis. The "classic" thioredoxin, identified in most species, is a 12-kDa protein with a Cys-Pro-Gly-Cys (CPGC) active site. However, in nematodes a larger protein, 16 kDa, with a Cys-Pro-Pro-Cys (CPPC) active site was identified. We report that in the parasitic nematode Haemonchus contortus, both the 12-kDa (HcTrx1) and the 16-kDa (HcTrx3) species are expressed through the life cycle. However, the HcTrx3 is expressed at higher concentrations. Recombinant HcTrx1 and HcTrx3 were produced and both reduced insulin at a rate similar to that observed with ovine (host) and Escherichia coli thioredoxins and both were regenerated by a mammalian thioredoxin reductase, demonstrating that they have similar thioredoxin activity. Unlike mammalian thioredoxins, both proteins were able to reduce oxidised glutathione and hydrogen peroxide. This suggests essential roles for these proteins in response to oxidative stress and the host immune attack. Analysis of ivermectin-resistant H. contortus showed that expression of both genes were increased in a drug-resistant strain relative to a sensitive strain. Involvement in drug resistance identifies these thioredoxin proteins as potential drug targets for parasite control.
Improving the gene structure annotation of the apicomplexan parasite Neospora caninum fulfils a vital requirement towards an in silico-derived vaccine
Publisher: Elsevier BV
Date: 04-2015
DOI: 10.1016/J.IJPARA.2015.01.006
Abstract: Neospora caninum is an apicomplexan parasite which can cause abortion in cattle, instigating major economic burden. Vaccination has been proposed as the most cost-effective control measure to alleviate this burden. Consequently the overriding aspiration for N. caninum research is the identification and subsequent evaluation of vaccine candidates in animal models. To save time, cost and effort, it is now feasible to use an in silico approach for vaccine candidate prediction. Precise protein sequences, derived from the correct open reading frame, are paramount and arguably the most important factor determining the success or failure of this approach. The challenge is that publicly available N. caninum sequences are mostly derived from gene predictions. Annotated inaccuracies can lead to erroneously predicted vaccine candidates by bioinformatics programs. This study evaluates the current N. caninum annotation for potential inaccuracies. Comparisons with annotation from a closely related pathogen, Toxoplasma gondii, are also made to distinguish patterns of inconsistency. More importantly, a mRNA sequencing (RNA-Seq) experiment is used to validate the annotation. Potential discrepancies originating from a questionable start codon context and exon boundaries were identified in 1943 protein coding sequences. We conclude, where experimental data were available, that the majority of N. caninum gene sequences were reliably predicted. Nevertheless, almost 28% of genes were identified as questionable. Given the limitations of RNA-Seq, the intention of this study was not to replace the existing annotation but to support or oppose particular aspects of it. Ideally, many studies aimed at improving the annotation are required to build a consensus. We believe this study, in providing a new resource on gene structure and annotation, is a worthy contributor to this endeavour.
New advances in the in-vitro culture of Dientamoeba fragilis
Publisher: Cambridge University Press (CUP)
Date: 16-02-2012
DOI: 10.1017/S0031182012000145
Abstract: Dientamoeba fragilis is an intestinal protozoan in humans that is commonly associated with diarrhoea and other gastrointestinal complaints. Studies conducted to investigate the biology of this parasite are limited by methods for in vitro cultivation. The objective of this study was to improve a biphasic culture medium, based on the Loeffler's slope, by further supplementation in order to increase the yield of trophozoites in culture. The current in vitro culture of D. fragilis is a xenic culture with a mix of bacteria. Three different liquid overlays were evaluated including Earle's balanced salt solution (EBSS), PBS and Dulbecco's modified PBS (DPBS), for their ability to support the in vitro growth of D. fragilis trophozoites. Out of these 3 overlays EBSS gave the highest increase in the trophozoite numbers. The effect of supplementation was analysed by supplementing EBSS with ascorbic acid, ferric ammonium citrate, L-cysteine, cholesterol and alpha-lipoic acid and quantification of in vitro growth by cell counts. A new liquid overlay is here described based upon EBSS supplemented with cholesterol and ferric ammonium citrate that, in conjunction with the Loeffler's slope, supports the growth of D. fragilis trophozoites in vitro . This modified overlay supported a 2-fold increase in the numbers of trophozoite in culture from all 4 D. fragilis isolates tested, when compared to a PBS overlay. These advances enable the harvest of a larger number of trophozoites needed for further studies on this parasite.
Enteric protozoa in the developed world: A public health perspective
Publisher: American Society for Microbiology
Date: 07-2012
DOI: 10.1128/CMR.05038-11
Abstract: Several enteric protozoa cause severe morbidity and mortality in both humans and animals worldwide. In developed settings, enteric protozoa are often ignored as a cause of diarrheal illness due to better hygiene conditions, and as such, very little effort is used toward laboratory diagnosis. Although these protozoa contribute to the high burden of infectious diseases, estimates of their true prevalence are sometimes affected by the lack of sensitive diagnostic techniques to detect them in clinical and environmental specimens. Despite recent advances in the epidemiology, molecular biology, and treatment of protozoan illnesses, gaps in knowledge still exist, requiring further research. There is evidence that climate-related changes will contribute to their burden due to displacement of ecosystems and human and animal populations, increases in atmospheric temperature, flooding and other environmental conditions suitable for transmission, and the need for the reuse of alternative water sources to meet growing population needs. This review discusses the common enteric protozoa from a public health perspective, highlighting their epidemiology, modes of transmission, prevention, and control. It also discusses the potential impact of climate changes on their epidemiology and the issues surrounding waterborne transmission and suggests a multidisciplinary approach to their prevention and control.
Resistance screening and trend analysis of imported falciparum malaria in NSW, Australia (2010 to 2016)
Publisher: Public Library of Science (PLoS)
Date: 29-05-2018
Performance characteristics and optimisation of cut-off values of two enzyme-linked immunosorbent assays for the detection of antibodies to Neospora caninum in the serum of cattle
Publisher: Elsevier BV
Date: 08-2006
DOI: 10.1016/J.VETPAR.2006.03.016
Abstract: To determine the performance characteristics of two enzyme-linked immunosorbent assays (ELISAs) manufactured by Institut Pourquier (IP) for the detection of antibodies against Neospora caninum in bovine sera. Sera from 526 cattle were assayed in two ELISAs (IP) for the detection of anti-N. caninum antibodies. Results from a further ELISA (IDEXX) were used to provide the "gold standard"N. caninum infection status of the cattle and the ELISA results assessed by two-graph receiver operating characteristic (TG-ROC) analysis. TG-ROC analysis suggested changes to one of the IP ELISA protocols, arriving at a cut-off threshold that was different to the one recommended by the manufacturer. With that change, both of the ELISAs performed with high sensitivity and specificity (in excess of 98%) for bovine sera. The analysis of the two IP ELISAs when used on in idual bovine sera demonstrated high sensitivity and specificity. TG-ROC analyses optimised the cut-off point suggested by the manufacturer for one of these commercial diagnostic assays and found agreement with the manufacturer's cut-off regarding the other assay. This will help with the accurate identification of infected animals and thereby contributing to the control of neosporosis.
A unique thioredoxin of the parasitic nematode Haemonchus contortus with glutaredoxin activity
Publisher: Elsevier BV
Date: 03-2009
DOI: 10.1016/J.FREERADBIOMED.2008.11.009
Abstract: The dependency of parasites on the cellular redox systems has led to their investigation as novel drug targets. Defence against oxidative damage is through the thioredoxin and glutathione systems. The classic thioredoxin is identified by the active site Cys-Gly-Pro-Cys (CGPC). Here we describe the identification of a unique thioredoxin in the parasitic nematode, Haemonchus contortus. This thioredoxin-related protein, termed HcTrx5, has an arginine in its active site (Cys-Arg-Ser-Cys CRSC) that is not found in any other organism. Recombinant HcTrx5 was able to reduce the disulfide bond in insulin, and be regenerated by mammalian thioredoxin reductase with a K(m) 2.19+/-1.5 microM, similar to the classic thioredoxins. However, it was also able to reduce insulin when glutathione and glutathione reductase replaced the thioredoxin reductase. When coupled with H. contortus peroxiredoxin, HcTrx5 was active using either the thioredoxin reductase or the glutathione and glutathione reductase. HcTrx5 is expressed through the life cycle, with highest expression in the adult stage. The unique activity of this thioredoxin makes it a potential drug target for the control of this parasite.
Comparison Of The Biological Characteristics Of Two Isolates Of Neospora Caninum
Publisher: Cambridge University Press (CUP)
Date: 04-1999
DOI: 10.1017/S0031182098003898
Abstract: This study compared the biological and genetic properties of a bovine (NC-SweB1) and a canine (NC-Liverpool) isolate of Neospora caninum . A mouse model for CNS infection demonstrated marked differences in pathogenicity between the isolates. NC-Liverpool induced severe clinical signs of neosporosis in 57/58 mice including discoordinated movement, hindlimb paralysis and coat ruffling with severe weight loss. In contrast NC-SweB1 induced similar but less severe symptoms in a much smaller proportion of mice over the same time-period. Statistically significant differences were observed between the isolates in the response (mean weight loss) of mice through time to the different doses inoculated. Histopathological effects on brain tissue reflected the isolate-based differences described above. NC-Liverpool infection resulted in intense inflammatory infiltrates and highly necrotic lesions whereas NC-SweB1 induced a milder meningoencephalitis. Passage in cell-culture over a period of 14 months did not affect the pathogenicity of NC-Liverpool. Immunoblots showed that antibodies to N. caninum appeared earlier in mice inoculated with NC-Liverpool than with NC-SweB1. Finally, RAPD–PCR analysis of NC-Liverpool DNA generated profiles distinct from that observed with DNA from NC-SweB1 or Toxoplasma gondii . In summary this study provides evidence for significant biological and genetic differences between 2 isolates of N. caninum .
Evaluation of multiplex tandem real-time PCR for Detection of Cryptosporidium spp., Dientamoeba fragilis, Entamoeba histolytica, and Giardia intestinalis in clinical stool samples
Publisher: American Society for Microbiology
Date: 2011
DOI: 10.1128/JCM.01796-10
Abstract: The aim of this study was to describe the first development and evaluation of a multiplex tandem PCR (MT-PCR) assay for the detection and identification of 4 common pathogenic protozoan parasites, Cryptosporidium spp., Dientamoeba fragilis , Entamoeba histolytica , and Giardia intestinalis , from human clinical s les. A total of 472 fecal s les submitted to the Department of Microbiology at St. Vincent's Hospital were included in the study. The MT-PCR assay was compared to four real-time PCR (RT-PCR) assays and microscopy by a traditional modified iron hematoxylin stain. The MT-PCR detected 28 G. intestinalis , 26 D. fragilis , 11 E. histolytica , and 9 Cryptosporidium sp. isolates. Detection and identification of the fecal protozoa by MT-PCR demonstrated 100% correlation with the RT-PCR results, and compared to RT-PCR, MT-PCR exhibited 100% sensitivity and specificity, while traditional microscopy of stained fixed fecal smears exhibited sensitivities and specificities of 56% and 100% for Cryptosporidium spp., 38% and 99% for D. fragilis , 47% and 97% for E. histolytica , and 50% and 100% for G. intestinalis . No cross-reactivity was detected in 100 stool s les containing various other bacterial, viral, and protozoan species. The MT-PCR assay was able to provide rapid, sensitive, and specific simultaneous detection and identification of the four most important diarrhea-causing protozoan parasites that infect humans. This study also highlights the lack of sensitivity demonstrated by microscopy, and thus, molecular methods such as MT-PCR must be considered the diagnostic methods of choice for enteric protozoan parasites.
Comparison of enteric protozoan infections in four Australian hospitals: variable tests and variable results
Publisher: Cambridge University Press (CUP)
Date: 2016
DOI: 10.1017/PAO.2016.7
Abstract: There is limited evidence of the prevalence of enteric protozoon infections in developed settings. We estimated the prevalence of enteric protozoa and evaluated the outcome of testing algorithms used in hospital settings in Sydney, Australia. This retrospective study assessed microbiological data from four public clinical laboratories. Pooled data from the four hospitals revealed the most common enteric protozoon detected was Blastocystis spp. in an average of 5·4% of cases, followed by Giardia intestinalis (1·1%) and Dientamoeba fragilis (0·8%). Protozoon detection rates between hospitals were significantly different and could be based on multiple factors. The modified iron haematoxylin staining method, consistently detected higher rates of Blastocystis spp., and G. intestinalis in comparison with microscopy of wet preparations, as well as higher rates of G. intestinalis and Cryptosporidium when compared with enzyme immunoassay. The study concludes that there are multiple factors that contribute to the variability in protozoa detection rates in metropolitan hospitals, including widespread variability in the testing protocols for enteric protozoa, in idual and population characteristics. A gold standard approach for diagnosis of enteric protozoa is recommended. Molecular diagnostic methods such as polymerase chain reaction would provide consistency across laboratories and yield more reliable estimates of the actual prevalence of enteric protozoa.
A second generation multiplex PCR for typing strains of Neospora caninum using six DNA targets
Publisher: Elsevier BV
Date: 02-2010
DOI: 10.1016/J.MCP.2009.08.002
Abstract: Genetic ersity of Neospora caninum was investigated through a study of repetitive sequences found in the genome of this species. Twenty different loci were studied, and three were identified that varied in repeat content amongst isolates. No relationship was found between the copy number of repetitive sequences present and host type or geographical location from which the isolates were derived. A multiplex PCR assay was developed for multilocus-strain typing using three microsatellites and three minisatellites, based on the polymorphisms found in the repetitive sequences. This study therefore extends knowledge on the repetitive sequences found in the N. caninum genome and the ersity found within the species. It also provides a second generation multiplex assay that can be used to study the biology of N. caninum. In addition, this study included Neospora hughesi (along with other closely related apicomplexans) as controls. The present study shows N. hughesi to be quite distinct from N. caninum in these repetitive sequences, thereby potentially providing a new approach for the differentiation of these two taxa.
Laboratory Diagnostic Techniques for Entamoeba Species
Publisher: American Society for Microbiology
Date: 07-2007
DOI: 10.1128/CMR.00004-07
Abstract: The genus Entamoeba contains many species, six of which ( Entamoeba histolytica, Entamoeba dispar, Entamoeba moshkovskii, Entamoeba polecki, Entamoeba coli , and Entamoeba hartmanni ) reside in the human intestinal lumen. Entamoeba histolytica is the causative agent of amebiasis and is considered a leading parasitic cause of death worldwide in humans. Although recent studies highlight the recovery of E. dispar and E. moshkovskii from patients with gastrointestinal symptoms, there is still no convincing evidence of a causal link between the presence of these two species and the symptoms of the host. New approaches to the identification of E. histolytica are based on detection of E. histolytica -specific antigen and DNA in stool and other clinical s les. Several molecular diagnostic tests, including conventional and real-time PCR, have been developed for the detection and differentiation of E. histolytica , E. dispar , and E. moshkovskii in clinical s les. The purpose of this review is to discuss different methods that exist for the identification of E. histolytica , E. dispar , and E. moshkovskii which are available to the clinical diagnostic laboratory. To address the need for a specific diagnostic test for amebiasis, a substantial amount of work has been carried out over the last decade in different parts of the world. The molecular diagnostic tests are increasingly being used for both clinical and research purposes. In order to minimize undue treatment of in iduals infected with other species of Entamoeba such as E. dispar and E. moshkovskii , efforts have been made for specific diagnosis of E. histolytica infection and not to treat based simply on the microscopic examination of Entamoeba species in the stool. The incorporation of many new technologies into the diagnostic laboratory will lead to a better understanding of the public health problem and measures to control the disease.
Re-evaluating the economics of neosporosis control.
Publisher: Elsevier BV
Date: 10-2008
Limited genetic diversity among genotypes of Enterocytozoon bieneusi strains isolated from HIV-infected patients from Sydney, Australia
Publisher: Microbiology Society
Date: 03-03-1970
Abstract: Microsporidia are intracellular parasites, with over 1200 species belonging to 143 genera described to date. They are opportunistic pathogens in humans and can cause chronic diarrhoea in immunosuppressed patients. Both Enterocytozoon bieneusi and Encephalitozoon intestinalis cause intestinal disease, with Enterocytozoon bieneusi more commonly identified in patients with human immunodeficiency virus (HIV) infection. In this study, intestinal microsporidial clinical isolates from patients in Sydney, Australia, were genotyped. All specimens were from HIV-infected men with low CD4 + T-cell counts ( cells mm −3 ). Genotyping of the internal transcribed spacer regions of the rRNA gene showed the presence of only one genotype, the anthroponotic Enterocytozoon bieneusi genotype B strain. This study thus highlighted the limited genetic ersity among Australian Enterocytozoon bieneusi isolates, and it is hypothesized that, due to the reduced incidence of microsporidia and the subsequent reduction in the human reservoir of the anthroponotic genotype B, locally acquired intestinal microsporidiosis will rarely be seen in HIV-infected persons undergoing highly active antiretroviral therapy in the future in Australia.
Development Of A Single Tube Nested Polymerase Chain Reaction Assay For The Detection Of Neospora Caninum DNA
Publisher: Elsevier BV
Date: 10-1999
DOI: 10.1016/S0020-7519(99)00144-7
Abstract: Sensitive detection techniques are required to study the life cycle of Neospora caninum and to diagnose infections. In this study, we describe the development of a PCR assay for N. caninum based on two successive lification steps within a single tube. This technique, called single tube nested PCR, was sensitive to a single copy of target sequence, and able to lify parasite DNA from biological specimens such as formalin-fixed, paraffin-embedded tissues of naturally infected dogs and cattle. An internal standard (or PCR MIMIC) is also described. This assay should prove useful in the study of the biology of N. caninum.
Leishmania (Sauroleishmania) A Comment On Classification
Publisher: Elsevier BV
Date: 04-1998
Irritable bowel syndrome: A review on the role of intestinal protozoa and the importance of their detection and diagnosis
Publisher: Elsevier BV
Date: 2007
DOI: 10.1016/J.IJPARA.2006.09.009
Abstract: Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder in which abdominal pain is associated with a defect or a change in bowel habits. Gut inflammation is one of the proposed mechanisms of pathogenesis. Recent studies have described a possible role for protozoan parasites, such as Blastocystis hominis and Dientamoeba fragilis, in the etiology of IBS. Dientamoeba fragilis is known to cause IBS-like symptoms and has a propensity to cause chronic infections but its diagnosis relies on microscopy of stained smears, which many laboratories do not perform, thereby leading to the misdiagnosis of dientamoebiasis as IBS. The role of B. hominis as an etiological agent of IBS is inconclusive, due to contradictory reports and the controversial nature of B. hominis as a human pathogen. Although Entamoeba histolytica infections occur predominately in developing regions of the world, clinical diagnosis of amebiasis is often difficult because symptoms of patients with IBS may closely mimic those patients with non-dysenteric amoebic colitis. Clinical manifestations of Giardia intestinalis infection also vary from asymptomatic carriage to acute and chronic diarrhoea with abdominal pain. These IBS-like symptoms can be continuous, intermittent, sporadic or recurrent, sometimes lasting years without correct diagnosis. It is essential that all patients with IBS undergo routine parasitological investigations in order to rule out the presence of protozoan parasites as the causative agents of the clinical signs.
Reduction in transplacental transmission of Neospora caninum in outbred mice by vaccination
Publisher: Elsevier BV
Date: 06-2005
DOI: 10.1016/J.IJPARA.2005.03.006
Abstract: Infection with the protozoan parasite Neospora caninum is an important cause of abortion in cattle. A major source of infection is transplacental transfer of the parasite from mother to offspring during pregnancy. This study describes investigations on the immunisation of outbred Qs mice before pregnancy with live or a crude lysate of N. caninum (NC-Nowra isolate) to prevent transplacental transfer of a challenge infection administered during pregnancy. Parasites present in the brains of pups from mice challenged with N. caninum (NC-Liverpool) were detected by PCR. Injection of live NC-Nowra tachyzoites before pregnancy dramatically reduced transplacental transfer from 75 to 0.8% in one experiment and from 76 to 8% in a second experiment. Injection of a crude lysate of NC-Nowra tachyzoites reduced transplacental transfer from 67 to 53% in one experiment and from 76 to 63% in a second experiment. Analysis of N. caninum-specific IgG1 and IgG2a antibody levels prior to pregnancy and challenge showed that NC-Nowra lysate induced a response skewed towards IgG1 whereas live parasites induced both IgG1 and IgG2a antibodies. After pregnancy and a challenge infection, a similar IgG1/IgG2a response was seen in all challenged groups. These results provide further positive support for the hypothesis that transplacental transmission of this parasite is preventable by vaccination.
Traveller sentinels for global surveillance of malaria drug resistance and diagnostic test evasion
Publisher: Elsevier BV
Date: 02-2019
The Relationship Of Hammondia Hammondi And Sarcocystis Mucosa To Other Heteroxenous Cyst-farming Coccidia As Inferred By Phylogenetic Analysis Of The 18s Ssu Ribosomal DNA Sequence
Publisher: Cambridge University Press (CUP)
Date: 08-1999
DOI: 10.1017/S0031182099004618
Abstract: The complete sequence of the 18S small subunit (SSU) ribosomal DNA of Hammondia hammondi and Sarcocystis mucosa was obtained and compared to SSU rDNA sequences of Neospora caninum , Toxoplasma gondii , Besnoitia besnoiti , 2 species of Frenkelia , 3 species of Isospora , and 13 species of Sarcocystis . Analyses showed that H. hammondi and T. gondii are monophyletic and that these taxa shared a common ancestor with N. caninum and B. besnoiti . The weight of evidence shows that S. mucosa , S. neurona , and Frenkelia species form a clade thereby supporting the conclusion that Sarcocystis is paraphyletic.
Extensive production of Neospora caninum tissue cysts in a carnivorous marsupial succumbing to experimental neosporosis
Publisher: Springer Science and Business Media LLC
Date: 02-06-2011
Abstract: Experimental infections of Sminthopsis crassicaudata , the fat-tailed dunnart, a carnivorous marsupial widely distributed throughout the arid and semi-arid zones of Australia, show that this species can act as an intermediate host for Neospora caninum . In contrast to existing models that develop relatively few N. caninum tissue cysts, dunnarts offer a new animal model in which active neosporosis is dominated by tissue cyst production. The results provide evidence for a sylvatic life cycle of N. caninum in Australia between marsupials and wild dogs. It establishes the foundation for an investigation of the impact and costs of neosporosis to wildlife.
The phylogeny of Neospora caninum
Publisher: Elsevier BV
Date: 04-1994
DOI: 10.1016/0166-6851(94)00033-6
Abstract: Morphological studies by electron microscopy on the protozoan Neospora caninum have shown that this organism possesses a subcellular structure typical of parasites classified in the family Sarcocystidae, subclass Coccidiasina of the phylum Apicomplexa. Using a strategy based on DNA sequence analysis of products derived by asymmetric PCR to determine the nucleotide sequences, we have tested the validity of this classification by comparing the small subunit ribosomal RNA (18S rRNA) gene sequences of N. caninum with those of other parasitic protozoa classified in the phylum Apicomplexa. The results of this analysis confirm the placing of N. caninum in the family Sarcocystidae and place it as a sister group to Toxoplasma gondii in the phylum Apicomplexa.
Tertiary structure-based prediction of conformational B-cell epitopes through B factors
Publisher: Oxford University Press (OUP)
Date: 11-06-2014
DOI: 10.1093/BIOINFORMATICS/BTU281
Abstract: Motivation: B-cell epitope is a small area on the surface of an antigen that binds to an antibody. Accurately locating epitopes is of critical importance for vaccine development. Compared with wet-lab methods, computational methods have strong potential for efficient and large-scale epitope prediction for antigen candidates at much lower cost. However, it is still not clear which features are good determinants for accurate epitope prediction, leading to the unsatisfactory performance of existing prediction methods. Method and results: We propose a much more accurate B-cell epitope prediction method. Our method uses a new feature B factor (obtained from X-ray crystallography), combined with other basic physicochemical, statistical, evolutionary and structural features of each residue. These basic features are extended by a sequence window and a structure window. All these features are then learned by a two-stage random forest model to identify clusters of antigenic residues and to remove isolated outliers. Tested on a dataset of 55 epitopes from 45 tertiary structures, we prove that our method significantly outperforms all three existing structure-based epitope predictors. Following comprehensive analysis, it is found that features such as B factor, relative accessible surface area and protrusion index play an important role in characterizing B-cell epitopes. Our detailed case studies on an HIV antigen and an influenza antigen confirm that our second stage learning is effective for clustering true antigenic residues and for eliminating self-made prediction errors introduced by the first-stage learning. Availability and implementation: Source codes are available on request. Contact: jinyan.li@uts.edu.au Supplementary information: Supplementary data are available at Bioinformatics online.
PCR Detection of Entamoeba histolytica , Entamoeba dispar , and Entamoeba moshkovskii in Stool Samples from
Publisher: American Society for Microbiology
Date: 03-2007
DOI: 10.1128/JCM.02144-06
Abstract: This study investigated the presence of Entamoeba histolytica , Entamoeba dispar , and Entamoeba moshkovskii in stool s les from a patient population in Sydney, Australia. Stool s les were tested by microscopy and PCR. Five patients were found with E. histolytica infections, while E. dispar and E. moshkovskii were observed in 63 (70.8%) and 55 (61.8%) patients, respectively, by PCR. This is the first study in Australia using molecular techniques to determine the presence of E. histolytica , E. dispar , and E. moshkovskii .
Eimeria species which infect the chicken contain virus-like RNA molecules
Publisher: Cambridge University Press (CUP)
Date: 10-1990
DOI: 10.1017/S0031182000063198
Abstract: There is increasing support for the presence of viruses and virus-like particles inside protozoan cells. This study describes viral-like RNA molecules that have been detected in two species of Eimeria that infect the chicken. The RNA molecule identified in E. maxima has been characterized: subcellular fractionation studies have shown that the RNA is present in the cytoplasm, probably as an abundant ribonucleoprotein that is insensitive to RNAse A treatment. Electron microscopy has demonstrated that this RNA molecule is double stranded. In addition, all E. maxima strains examined so far contain this RNA molecule.
Characterization of an outbred pregnant mouse model of Neospora caninum infection
Publisher: American Society of Parasitologists
Date: 08-2002
Laboratory diagnostics for human Leishmania infections: a polymerase chain reaction-focussed review of detection and identification methods.
Publisher: Springer Science and Business Media LLC
Date: 05-11-2022
DOI: 10.1186/S13071-022-05524-Z
Abstract: Leishmania infections span a range of clinical syndromes and impact humans from many geographic foci, but primarily the world’s poorest regions. Transmitted by the bite of a female sand fly, Leishmania infections are increasing with human movement (due to international travel and war) as well as with shifts in vector habitat (due to climate change). Accurate diagnosis of the 20 or so species of Leishmania that infect humans can lead to the successful treatment of infections and, importantly, their prevention through modelling and intervention programs. A multitude of laboratory techniques for the detection of Leishmania have been developed over the past few decades, and although many have drawbacks, several of them show promise, particularly molecular methods like polymerase chain reaction. This review provides an overview of the methods available to diagnostic laboratories, from traditional techniques to the now-preferred molecular techniques, with an emphasis on polymerase chain reaction-based detection and typing methods. Graphical abstract
Identification of Clinical Infections of Leishmania Imported into Australia: Revising Speciation with Polymerase Chain Reaction-RFLP of the Kinetoplast Maxicircle.
Publisher: American Society of Tropical Medicine and Hygiene
Date: 04-09-2019
Prevalence of antibodies to Neospora caninum in different canid populations
Publisher: JSTOR
Date: 12-1997
DOI: 10.2307/3284361
What is the global economic impact of Neospora caninum in cattle - The billion dollar question
Publisher: Elsevier BV
Date: 02-2013
DOI: 10.1016/J.IJPARA.2012.10.022
Abstract: Neospora caninum is regarded as one of the most important infectious causes of abortions in cattle worldwide, yet the global economic impact of the infection has not been established. A systematic review of the economic impact of N. caninum infections/abortions was conducted, searching PubMed with the terms 'cattle' and 'Neospora'. This yielded 769 publications and the abstracts were screened for economically relevant information (e.g. abortion prevalence and risk, serological prevalence). Further analysis was restricted to countries with at least five relevant publications. In total, 99 studies (12.9%) from 10 countries contained data from the beef industry (25 papers (25.3%)) and 72 papers (72.8%) from the dairy industry (with the remaining two papers (2.0%) describing general abortion statistics). The total annual cost of N. caninum infections/abortions was estimated to range from a median US $1.1 million in the New Zealand beef industry to an estimated median total of US $546.3 million impact per annum in the US dairy population. The estimate for the total median N. caninum-related losses exceeded US $1.298 billion per annum, ranging as high as US $2.380 billion. Nearly two-thirds of the losses were incurred by the dairy industry (US $842.9 million). Annual losses on in idual dairy farms were estimated to reach a median of US $1,600.00, while on beef farms these costs amounted to just US $150.00. Pregnant cows and heifers were estimated to incur, on average, a loss due to N. caninum of less than US $20.00 for dairy and less than US $5.00 for beef. These loss estimates, however, rose to ∼US $110.00 and US $40.00, respectively, for N. caninum-infected pregnant dairy and beef cows. This estimate of global losses due to N. caninum, with the identification of clear target markets (countries, as well as cattle industries), should provide an incentive to develop treatment options and/or vaccines.
Update on the Molecular Epidemiology and Diagnostic Tools for Blastocystis sp
Publisher: OMICS Publishing Group
Date: 2014
A Review of the Clinical Presentation of Dientamoebiasis
Publisher: American Society of Tropical Medicine and Hygiene
Date: 04-2010
Differences between Leishmania (Leishmania) chagasi, L. (L.) infantum and L. (L.) donovani as shown by DNA fingerprinting.
Publisher: FapUNIFESP (SciELO)
Date: 12-1991
Update on the pathogenic potential and treatment options for Blastocystis sp.
Publisher: Springer Science and Business Media LLC
Date: 2014
Prevalence of gastrointestinal pathogens in sub-saharan africa: Systematic review and meta-analysis
Publisher: PAGEPress Publications
Date: 05-09-2011
Semi-Quantitative, Duplexed qPCR Assay for the Detection of Leishmania spp. Using Bisulphite Conversion Technology
Publisher: MDPI AG
Date: 11-2019
DOI: 10.3390/TROPICALMED4040135
Abstract: Leishmaniasis is caused by the flagellated protozoan Leishmania, and is a neglected tropical disease (NTD), as defined by the World Health Organisation (WHO). Bisulphite conversion technology converts all genomic material to a simplified form during the lysis step of the nucleic acid extraction process, and increases the efficiency of multiplex quantitative polymerase chain reaction (qPCR) reactions. Through utilization of qPCR real-time probes, in conjunction with bisulphite conversion, a new duplex assay targeting the 18S rDNA gene region was designed to detect all Leishmania species. The assay was validated against previously extracted DNA, from seven quantitated DNA and cell standards for pan-Leishmania analytical sensitivity data, and 67 cutaneous clinical s les for cutaneous clinical sensitivity data. Specificity was evaluated by testing 76 negative clinical s les and 43 bacterial, viral, protozoan and fungal species. The assay was also trialed in a side-by-side experiment against a conventional PCR (cPCR), based on the Internal transcribed spacer region 1 (ITS1 region). Ninety-seven percent of specimens from patients that previously tested positive for Leishmania were positive for Leishmania spp. with the bisulphite conversion assay, and a limit of detection (LOD) of 10 copies per PCR was achieved, while the LOD of the ITS1 methodology was 10 cells/1000 genomic copies per PCR. This method of rapid, accurate and simple detection of Leishmania can lead to improved diagnosis, treatment and public health outcomes.
On the biological and genetic diversity in Neospora caninum
Publisher: MDPI AG
Date: 22-03-2010
DOI: 10.3390/D2030411
Subset partitioning of the ribosomal DNA smell subunit and its effects on the phylogeny of the Anopheles punctulatus group
Publisher: Wiley
Date: 10-2000
DOI: 10.1046/J.1365-2583.2000.00211.X
Abstract: A phylogenetic study, based on maximum parsimony, of ten species in the Anopheles punctulatus group of malaria vectors from the south-west Pacific was performed using structural and similarity-based DNA sequence alignments of the nuclear small ribosomal subunit (SSU = 18S). The structural alignment proved to be more informative than a computer generated similarity-based alignment. Analyses involving the full structural sequence alignment (2169 bp) and the helical regions (1547 bp) resolved a single tree of the same topology, while analyses using the similarity based alignment could not resolve the group. Studies on the three structural domains of the nuclear rDNA SSU identified domain 2 (769 bp) as the only region informative at the sibling-species level and resulted in the same tree as the full structural sequence and helical regions. The main conclusions of these studies were that the An. punctulatus group formed two clades: a Farauti clade containing members displaying an all black scaled proboscis (An. farauti 1-3 and 5-7) and a Punctulatus clade containing members that display some degree of white scaling on the proboscis (An. farauti 4, An. punctulatus and An. species near punctulatus). Anopheles koliensis can display either proboscis morphology and was positioned basal to the Farauti Clade. These results do not fully concord with those derived from the mitochondrial COII gene.
A live vaccine against Neospora caninum abortions in cattle
Publisher: Elsevier BV
Date: 03-2015
Bibliometric analysis of parasite vaccine research from 1990 to 2019.
Publisher: Elsevier BV
Date: 10-2023
A review of Dientamoeba fragilis carriage in humans: Several reasons why this organism should be considered in the diagnosis of gastrointestinal illness
Publisher: Informa UK Limited
Date: 2011
Abstract: Dientamoeba fragilis is a protozoan that inhabits the human gut. It is approximately 100 years since Dientamoeba's discovery and first description when it was described as a rare and harmless commensal. Since then it has struggled to gain recognition as a pathogen despite the evidence supporting its pathogenicity. Dientamoeba remains neglected, probably due to the misconceptions that it is uncommon and non-pathogenic. Usually, carriage of Dientamoeba is associated with symptoms such as abdominal pain and diarrhea. Moreover, antimicrobial therapy followed by resolution of symptoms coincides with the eradication of Dientamoeba. This manuscript reviews the scientific literature relating to Dientamoeba's prevalence and pathogenicity. While much of the evidence supporting its pathogenicity is only circumstantial, it is apparent that most researchers agree that Dientamoeba is pathogenic. Therefore, in symptomatic patients who harbor Dientamoeba and no other pathogen, Dientamoeba should be considered as the etiological agent and treated as such.
A review of the systematics, species identification and diagnostics of the Trypanosomatidae using the maxicircle kinetoplast DNA: from past to present.
Publisher: Elsevier BV
Date: 06-2020
Evaluation of the EasyScreen™ Enteric Parasite Detection Kit for the detection of Blastocystis spp., Cryptosporidium spp., Dientamoeba fragilis, Entamoeba complex, and Giardia intestinalis from clinic
Publisher: Elsevier BV
Date: 02-2014
DOI: 10.1016/J.DIAGMICROBIO.2013.10.013
Abstract: The aim of this study was to evaluate the EasyScreen™ Enteric Parasite Detection Kit (Genetic Signatures, Sydney, Australia) for the detection and identification of 5 common enteric parasites: Blastocystis spp., Cryptosporidium spp., Dientamoeba fragilis, Entamoeba complex, and Giardia intestinalis in human clinical s les. A total of 358 faecal s les were included in the study. When compared to real-time PCR and microscopy, the EasyScreen™ Enteric Parasite Detection Kit exhibited 92-100% sensitivity and 100% specificity and detected all commonly found genotypes and subtypes of clinically important human parasites. No cross reactivity was detected in stool s les containing various other bacterial, viral, and/or protozoan species. The EasyScreen™ PCR assay was able to provide rapid, sensitive, and specific simultaneous detection and identification of the 5 most important diarrhoea-causing enteric parasites that infect humans. It should be noted, however, that the EasyScreen™ Kit does not substitute for microscopy or for additional PCRs as it does not detect the pathogenic Coccidia spp. Cystoisospora belli or Cyclospora cayetanensis and it does not differentiate between pathogenic and nonpathogenic Entamoeba spp. This study also highlights the lack of sensitivity demonstrated by microscopy as such, molecular methods should be considered the diagnostic method of choice for enteric parasites.
On the efficacy and safety of vaccination in cattle with live tachyzoites of Neospora caninum for the prevention of Neospora-associated fetal loss in cattle
Publisher: American Society for Microbiology
Date: 2013
DOI: 10.1128/CVI.00225-12
Abstract: Infection of cattle with Neospora caninum may result in abortion or the birth of a congenitally infected calf. Vaccination with live N. caninum protects against experimental infection of cattle and mice, and the naturally attenuated Nc-Nowra strain of N. caninum is of particular interest as a potential vaccine candidate. Vaccination of heifers prior to breeding with live Nc-Nowra tachyzoites by either the subcutaneous or the intravenous route reduced the rate of abortion and the presence of the parasite in calves as determined by PCR and serology after infection of cows with a virulent isolate. Protected fractions were 55.6% to 85.2% depending on the route of vaccination and growth conditions of the vaccine strain, with cryopreserved Nc-Nowra tachyzoites being less effective, with a 25.9% protected fraction. Vaccination appeared to reduce the rate of pregnancy after artificial insemination in some groups compared to nonvaccinated, nonchallenged controls. One animal that was vaccinated but not challenged experienced an abortion, but Nc-Nowra could not be detected in any of the cows in this group or their progeny. This study confirms that live vaccination can be an effective method of preventing neosporosis in cattle and yet highlights the technical hurdle of preservation of live parasites that must be overcome for a vaccine to be commercially successful.
Codon Usage and Bias Among Individual Genes of the Coccidia and Piroplasms
Publisher: Cambridge University Press (CUP)
Date: 09-1994
DOI: 10.1017/S003118200007829X
Abstract: Codon usage has been analysed in in idual gene sequences, derived from a variety of parasitic protozoa in the class Sporozoa of the phylum Apicomplexa using metric multidimensional scaling. The two groups of codon usage patterns detected reflect the two main subgroups of organisms studied (the coccidia and the piroplasms), and it is the pattern usage of synonymous codons that has the largest influence on overall codon usage in the in idual genes, rather than being the pattern of amino acid composition of the gene product. The magnitude of the codon usage bias in the sequences was determined using three commonly used indices – N C' , GC 3s and B. In general, although relatively low levels of codon usage bias were detected in these gene sequences, codon usage bias does explain at least some of the codon usage patterns observed. Codon usage bias was observed to be dependent on the overall base composition of the genes analysed, which in turn was reflected in the types of codons that were either over-or under-represented in the nucleotide sequences. keeping with observations on prokaryotic organisms, it is speculated that the codon usage patterns detected in these parasitic protozoa are the result of directional mutation pressure on the base composition of the genomic DNA.
Twitter trends in #Parasitology determined by text mining and topic modelling
Publisher: Elsevier BV
Date: 2023
Recent trends in the use of social media in parasitology and the application of alternative metrics
Publisher: Elsevier BV
Date: 2021
Phylogenetic-relationships Between Toxoplasma And Sarcocystis Deduced From A Comparison Of 18s RDNA Sequences
Publisher: Cambridge University Press (CUP)
Date: 06-1995
DOI: 10.1017/S0031182000065239
Abstract: The current taxonomy of parasites in the genus Sarcocystis is largely based on morphological characteristics as well as on host specificity and life-cycle structure. Recently, phylogenetic analyses of partial ribosomal RNA (rRNA) sequences provided support for paraphyly of Sarcocystis . We have tested the validity of this hypothesis by sequencing the complete 18S rRNA genes of Sarcocystis arieticanis , Sarcocystis gigantea and Sarcocystis tenella and comparing them with gene sequences derived from other taxa of the phylum Apicomplexa. The results obtained from this study do not reject the hypothesis of monophyly of Sarcocystis species, although the bootstrap data were inconclusive for some species.
Machine learning and applications in microbiology
Publisher: Oxford University Press (OUP)
Date: 16-03-2021
Abstract: To understand the intricacies of microorganisms at the molecular level requires making sense of copious volumes of data such that it may now be humanly impossible to detect insightful data patterns without an artificial intelligence application called machine learning. Applying machine learning to address biological problems is expected to grow at an unprecedented rate, yet it is perceived by the uninitiated as a mysterious and daunting entity entrusted to the domain of mathematicians and computer scientists. The aim of this review is to identify key points required to start the journey of becoming an effective machine learning practitioner. These key points are further reinforced with an evaluation of how machine learning has been applied so far in a broad scope of real-life microbiology ex les. This includes predicting drug targets or vaccine candidates, diagnosing microorganisms causing infectious diseases, classifying drug resistance against antimicrobial medicines, predicting disease outbreaks and exploring microbial interactions. Our hope is to inspire microbiologists and other related researchers to join the emerging machine learning revolution.
Culture of Neospora caninum in the presence of a Mycoplasma Removal Agent results in the selection of a mutant population of tachyzoites
Publisher: Cambridge University Press (CUP)
Date: 22-02-2005
DOI: 10.1017/S0031182004007115
Abstract: Mycoplasmas are common contaminants of eukaryotic cells grown in tissue culture. A commercially available Mycoplasma Removal Agent (MRA) was therefore assessed for its effect on tachyzoites of Neospora caninum , in order to determine its suitability for further use in parasite cell cultures. Analyses of tachyzoite and excreted-secreted proteins and antigens by SDS-PAGE and Western blotting show that MRA treatment results in the rapid selection of a mutant population that differs from the control and parental lines in its protein and antigen content. The treatment of N. caninum cultures with MRA is therefore not recommended for the eradication of Mycoplasma .
Epidemiology and associated risk factors of giardiasis in a peri-urban setting in New South Wales Australia
Publisher: Cambridge University Press (CUP)
Date: 28-09-2019
DOI: 10.1017/S0950268818002637
Abstract: Giardiasis is one of the most important non-viral causes of human diarrhoea. Yet, little is known about the epidemiology of giardiasis in the context of developed countries such as Australia and there is a limited information about local sources of exposure to inform prevention strategies in New South Wales. This study aimed to (1) describe the epidemiology of giardiasis and (2) identify potential modifiable risk factors associated with giardiasis that are unique to south-western Sydney, Australia. A 1:2 matched case-control study of 190 confirmed giardiasis cases notified to the South-Western Local Health District Public Health Unit from January to December 2016 was employed to investigate the risk factors for giardiasis. Two groups of controls were selected to increase response rate Pertussis cases and neighbourhood (NBH) controls. A matched analysis was carried out for both control groups separately. Variables with a significant odds ratio (OR) in the univariate analysis were placed into a multivariable regression for each matched group, respectively. In the regression model with the NBH controls, age and sex were controlled as potential confounders. Identified risk factors included being under 5 years of age (aOR = 7.08 95% confidence intervals (CI) 1.02–49.36), having a household member diagnosed with a gastrointestinal illness (aOR = 15.89 95% CI 1.53–164.60) and having contact with farm animals, domestic animals or wildlife (aOR = 3.03 95% CI 1.08–8.54). Cases that travelled overseas were at increased risk of infection (aOR = 19.89 95% CI 2.00–197.37) when compared with Pertussis cases. This study provides an update on the epidemiology and associated risk factors of a neglected tropical disease, which can inform enhanced surveillance and prevention strategies in the developed metropolitan areas.
A novel strategy for classifying the output from an in silicovaccine discovery pipeline for eukaryotic pathogens using machine learning algorithms
Publisher: Springer Science and Business Media LLC
Date: 02-11-2013
Abstract: An in silico vaccine discovery pipeline for eukaryotic pathogens typically consists of several computational tools to predict protein characteristics. The aim of the in silico approach to discovering subunit vaccines is to use predicted characteristics to identify proteins which are worthy of laboratory investigation. A major challenge is that these predictions are inherent with hidden inaccuracies and contradictions. This study focuses on how to reduce the number of false candidates using machine learning algorithms rather than relying on expensive laboratory validation. Proteins from Toxoplasma gondii, Plasmodium sp ., and Caenorhabditis elegans were used as training and test datasets. The results show that machine learning algorithms can effectively distinguish expected true from expected false vaccine candidates (with an average sensitivity and specificity of 0.97 and 0.98 respectively), for proteins observed to induce immune responses experimentally. Vaccine candidates from an in silico approach can only be truly validated in a laboratory. Given any in silico output and appropriate training data, the number of false candidates allocated for validation can be dramatically reduced using a pool of machine learning algorithms. This will ultimately save time and money in the laboratory.
Australian dingoes are definitive hosts of Neospora caninum
Publisher: Elsevier BV
Date: 07-2010
DOI: 10.1016/J.IJPARA.2010.01.008
Abstract: To provide objective data on the potential role of dingoes (Canis lupus dingo) in the life cycle of Neospora caninum in Australia, the production of N. caninum oocysts by experimentally infected canids was investigated. Three dingo pups raised in captivity and three domestic dogs were fed tissue from calves infected with an Australian isolate of N. caninum, Nc-Nowra. Oocysts of N. caninum, confirmed by species-specific PCR, were shed in low numbers by one dingo pup at 12-14 days p.i. The remaining animals did not shed oocysts. Furthermore, the blood from two out of three dingoes tested positive for DNA of N. caninum using PCR tests at 14 and 28 days p.i. Oocyst shedding from the intestinal tract of a dingo demonstrates that dingoes are definitive hosts of N. caninum and horizontal transmission of N. caninum from dingoes to farm animals and wildlife may occur in Australia.
Evaluation of three diagnostic methods, including real-time PCR, for detection of Dientamoeba fragilis in stool specimens
Publisher: American Society for Microbiology
Date: 2006
DOI: 10.1128/JCM.44.1.232-235.2006
Abstract: Dientamoeba fragilis is a protozoan parasite of humans that infects the mucosa of the large intestine and is associated with gastrointestinal disease. We developed a 5′ nuclease (TaqMan)-based real-time PCR assay, targeting the small subunit rRNA gene, for the detection of D. fragilis in human stool specimens and compared its sensitivity and specificity to conventional PCR and microscopic examination by a traditional modified iron-hematoxylin staining procedure. Real-time PCR exhibited 100% sensitivity and specificity.
Evaluation of recombinant proteins of Neospora caninum as vaccine candidates (in a mouse model)
Publisher: Elsevier BV
Date: 11-2008
DOI: 10.1016/J.VACCINE.2008.08.043
Abstract: Abortion, resulting from infections by the parasite Neospora caninum, is a major cause of economic loss to both the dairy and beef industries of cattle-producing countries of the world. Vaccination as a means of preventing abortion and/or infection represents a viable control strategy indeed a commercial vaccine is available in some countries, albeit of unknown efficacy. The commercial vaccine is based on inactivated tachyzoites of N. caninum but other approaches based on lysates and recombinant antigens of N. caninum may also be feasible. In this study we have used an immunisation/challenge model of transplacental transmission, based on the Qs mouse with an Nc-Liverpool challenge, to investigate the vaccine potential of a number of formulations based on four recombinant proteins of N. caninum (GRA1, GRA2, MIC10, and p24B). All formulations studied were immunogenic in the mouse when assessed by ELISA using sonicated tachyzoite antigen as the target antigen. In one experiment, a mixture of MIC10 and p24B produced partial protection against transplacental transmission of N. caninum in this mouse model in contrast a live infection of tachyzoites of NC-Nowra given before pregnancy always induces very high levels of protective immunity. The field of vaccines against Neospora-associated abortion in cattle is discussed.
Clinical Significance of Enteric Protozoa in the Immunosuppressed Human Population
Publisher: American Society for Microbiology
Date: 10-2009
DOI: 10.1128/CMR.00017-09
Abstract: Globally, the number of immunosuppressed people increases each year, with the human immunodeficiency virus (HIV) pandemic continuing to spread unabated in many parts of the world. Immunosuppression may also occur in malnourished persons, patients undergoing chemotherapy for malignancy, and those receiving immunosuppressive therapy. Components of the immune system can be functionally or genetically abnormal as a result of acquired (e.g., caused by HIV infection, lymphoma, or high-dose steroids or other immunosuppressive medications) or congenital illnesses, with more than 120 congenital immunodeficiencies described to date that either affect humoral immunity or compromise T-cell function. All in iduals affected by immunosuppression are at risk of infection by opportunistic parasites (such as the microsporidia) as well as those more commonly associated with gastrointestinal disease (such as Giardia ). The outcome of infection by enteric protozoan parasites is dependent on absolute CD4 + cell counts, with lower counts being associated with more severe disease, more atypical disease, and a greater risk of disseminated disease. This review summarizes our current state of knowledge on the significance of enteric parasitic protozoa as a cause of disease in immunosuppressed persons and also provides guidance on recent advances in diagnosis and therapy for the control of these important parasites.
Activity of benzimidazoles againstDientamoeba fragilis(Trichomonadida, Monocercomonadidae)in vitroand correlation of beta-tubulin sequences as an indicator of resistance
Publisher: EDP Sciences
Date: 2014
Recent Advances in Molecular Biology of Parasitic Viruses
Publisher: Bentham Science Publishers Ltd.
Date: 03-04-2014
DOI: 10.2174/1871526514666140713160905
Abstract: The numerous protozoa that can inhabit the human gastro-intestinal tract are known, yet little is understood of the viruses which infect these protozoa. The discovery, morphologic details, purification methods of virus-like particles, genome and proteome of the parasitic viruses, Entamoeba histolytica, Giardia lamblia, Trichomonas vaginalis, and the Eimeria sp. are described in this review. The protozoan viruses share many common features: most of them are RNA or double-stranded RNA viruses, ranging between 5 and 8 kilobases, and are spherical or icosahedral in shape with an average diameter of 30-40 nm. These viruses may influence the function and pathogenicity of the protozoa which they infect, and may be important to investigate from a clinical perspective. The viruses may be used as specific genetic transfection vectors for the parasites and may represent a research tool. This review provides an overview on recent advances in the field of protozoan viruses.
Molecular detection of drug resistant malaria in Southern Thailand.
Publisher: Springer Science and Business Media LLC
Date: 15-08-2019
A Gene-Based Positive Selection Detection Approach to Identify Vaccine Candidates Using Toxoplasma gondii as a Test Case Protozoan Pathogen
Publisher: Frontiers Media SA
Date: 20-08-2018
Influenza A HA's conserved epitopes and broadly neutralizing antibodies: a prediction method
Publisher: World Scientific Pub Co Pte Lt
Date: 10-2014
DOI: 10.1142/S0219720014500231
Abstract: A conserved epitope is an epitope retained by multiple strains of influenza as the key target of a broadly neutralizing antibody. Identification of conserved epitopes is of strong interest to help design broad-spectrum vaccines against influenza. Conservation score measures the evolutionary conservation of an amino acid position in a protein based on the phylogenetic relationships observed amongst homologous sequences. Here, Average Amino Acid Conservation Score (AAACS) is proposed as a method to identify HA's conserved epitopes. Our analysis shows that there is a clear distinction between conserved epitopes and nonconserved epitopes in terms of AAACS. This method also provides an excellent classification performance on an independent dataset. In contrast, alignment-based comparison methods do not work well for this problem, because conserved epitopes to the same broadly neutralizing antibody are usually not identical or similar. Location-based methods are not successful either, because conserved epitopes are located at both the less-conserved globular head (HA1) and the more-conserved stem (HA2). As a case study, two conserved epitopes on HA are predicted for the influenza A virus H7N9: One should match the broadly neutralizing antibodies CR9114 or FI6v3, while the other is new and requires validation by wet-lab experiments.
Bulky Trichomonad Genomes: Encoding a Swiss Army Knife
Publisher: Elsevier BV
Date: 10-2016
Abstract: The trichomonads are a remarkably successful lineage of ancient, predominantly parasitic protozoa. Recent molecular analyses have revealed extensive duplication of certain genetic loci in trichomonads. Consequently, their genomes are exceptionally large compared to other parasitic protozoa. Retention of these large gene expansions across different trichomonad families raises the question: do these duplications afford an advantage? Many duplicated genes are linked to the parasitic lifestyle and some are regulated differently to their paralogues, suggesting they have acquired new functions. It is proposed that these large genomes encode a Swiss army knife of sorts, packed with a multitude of tools for use in many different circumstances. This may have bestowed trichomonads with the extraordinary versatility that has undoubtedly contributed to their success.
Lyme disease: a search for a causative agent in ticks in south-eastern Australia.
Publisher: Cambridge University Press (CUP)
Date: 04-1994
DOI: 10.1017/S0950268800057782
Abstract: Attempts were made to identify the causative organism of Lyme disease in Australia from possible tick vectors. Ticks were collected in coastal areas of New South Wales, Australia, from localities associated with putative human infections. The ticks were dissected a portion of the gut contents was examined for spirochaetes by microscopy, the remaining portion inoculated into culture media. The detection of spirochaetes in culture was performed using microscopy, and immunochemical and molecular (PCR) techniques. Additionally, whole ticks were tested with PCR for spirochaetes. From 1990 to 1992, approximately 12000 ticks were processed for spirochaetes. No evidence of Borrelia burgdorferi or any other spirochaete was recovered from or detected in likely tick vectors. Some spirochaete–like objects detected in the cultures were shown to be artifacts, probably aggregates of bacterial flagellae. There is no definitive evidence for the existence in Australia of B. burgdorferi the causative agent of true Lyme disease, or for any other tick–borne spirochaete that may be responsible for a local syndrome being reported as Lyme disease.
Applying Machine Learning to Predict the Exportome of Bovine and Canine Babesia Species That Cause Babesiosis
Publisher: MDPI AG
Date: 27-05-2021
DOI: 10.3390/PATHOGENS10060660
Abstract: Babesia infection of red blood cells can cause a severe disease called babesiosis in susceptible hosts. Bovine babesiosis causes global economic loss to the beef and dairy cattle industries, and canine babesiosis is considered a clinically significant disease. Potential therapeutic targets against bovine and canine babesiosis include members of the exportome, i.e., those proteins exported from the parasite into the host red blood cell. We developed three machine learning-derived methods (two novel and one adapted) to predict for every known Babesia bovis, Babesia bigemina, and Babesia canis protein the probability of being an exportome member. Two well-studied apicomplexan-related species, Plasmodium falciparum and Toxoplasma gondii, with extensive experimental evidence on their exportome or excreted/secreted proteins were used as important benchmarks for the three methods. Based on 10-fold cross validation and multiple train–validation–test splits of training data, we expect that over 90% of the predicted probabilities accurately provide a secretory or non-secretory indicator. Only laboratory testing can verify that predicted high exportome membership probabilities are creditable exportome indicators. However, the presented methods at least provide those proteins most worthy of laboratory validation and will ultimately save time and money.
Effects Of Nucleotide Sequence Alignment On Phylogeny Estimation A Case Study Of 18s RDNAs Of Apicomplexa
Publisher: Oxford University Press (OUP)
Date: 04-1997
DOI: 10.1093/OXFORDJOURNALS.MOLBEV.A025779
Abstract: The reconstruction of phylogenetic history is predicated on being able to accurately establish hypotheses of character homology, which involves sequence alignment for studies based on molecular sequence data. In an empirical study investigating nucleotide sequence alignment, we inferred phylogenetic trees for 43 species of the Apicomplexa and 3 of Dinozoa based on complete small-subunit rDNA sequences, using six different multiple-alignment procedures: manual alignment based on the secondary structure of the 18S rRNA molecule, and automated similarity-based alignment algorithms using the PileUp, ClustalW, TreeAlign, MALIGN, and SAM computer programs. Trees were constructed using neighboring-joining, weighted-parsimony, and maximum-likelihood methods. All of the multiple sequence alignment procedures yielded the same basic structure for the estimate of the phylogenetic relationship among the taxa, which presumably represents the underlying phylogenetic signal. However, the placement of many of the taxa was sensitive to the alignment procedure used and the different alignments produced trees that were on average more dissimilar from each other than did the different tree-building methods used. The multiple alignments from the different procedures varied greatly in length, but aligned sequence length was not a good predictor of the similarity of the resulting phylogenetic trees. We also systematically varied the gap weights (the relative cost of inserting a new gap into a sequence or extending an already-existing gap) for the ClustalW program, and this produced alignments that were at least as different from each other as those produced by the different alignment algorithms. Furthermore, there was no combination of gap weights that produced the same tree as that from the structure alignment, in spite of the fact that many of the alignments were similar in length to the structure alignment. We also investigated the phylogenetic information content of the helical and nonhelical regions of the rDNA, and conclude that the helical regions are the most informative. We therefore conclude that many of the literature disagreements concerning the phylogeny of the Apicomplexa are probably based on differences in sequence alignment strategies rather than differences in data or tree-building methods.
Repeated Dientamoeba fragilis Infections: A Case Report of Two Families from Sydney, Australia
Publisher: MDPI AG
Date: 10-11-2009
Abstract: We report cases of two unrelated families who both presented with recurrent Dienta-moeba fragilis infections. Subsequent antimicrobial therapy resulted in the clearance of D. fragilis and total resolution of gastrointestinal symptoms in both families. This report highlights the potentially recurrent nature of D. fragilis infections and the need for laboratories to routinely test for this organism.
The complete coding region of the maxicircle as a superior phylogenetic marker for exploring evolutionary relationships between members of the Leishmaniinae
Publisher: Elsevier BV
Date: 06-2019
DOI: 10.1016/J.MEEGID.2019.02.002
Abstract: The mitochondrial DNA (mtDNA) is a potentially valuable phylogenetic marker given its presence across all eukaryotic taxa and its relative conservation in structure and sequence. In trypanosomatids, a homologue of the mtDNA referred to as the maxicircle DNA, is located within a specialised structure in the single mitochondrion of the trypanosomatids called the kinetoplast a high molecular weight network of DNA composed of thousands of catenated minicircles and a smaller number of larger maxicircles. Unique to the kinetoplastid protists, the maxicircle component of this complex network could represent a desirable target for taxonomic inquiry that may also facilitate exploration of the evolutionary history of this important group of parasites. The aim of this study was to investigate the phylogenetic value of the trypanosomatid maxicircle for these applications. Maxicircle sequences were obtained either by assembling raw sequence data publicly accessible in online databases (i.e., NCBI), or by lification of novel maxicircle sequences from trypanosomatid DNA using long-range (LR) PCR with subsequent Illumina sequencing. This procedure facilitated the generation of nearly complete maxicircle sequences (i.e., excluding the ergent region) for numerous dixenous and monoxenous trypanosomatid species. Annotation of each maxicircle sequence confirmed that their structure was conserved across all taxa examined. Phylogenetic analyses confirmed that Z. australiensis showed a greater genetic relatedness with the dixenous trypanosomatids of the genera Leishmania and Endotrypanum, as opposed to members of the monoxenous genera Crithidia and Leptomonas. Additionally, molecular clock analysis supported that the dixenous Leishmaniinae appeared approximately 75 million years ago during the breakup of Gondwana. In line with previous studies, our results support the Supercontinents hypothesis regarding the origin of dixenous Leishmaniinae. Ultimately, we demonstrate that the maxicircle represents an excellent phylogenetic marker for studying the evolutionary history of trypanosomatids, resulting in trees with very high bootstrap support values.
Angiostrongylus cantonensis: a review of its distribution, molecular biology and clinical significance as a human pathogen - CORRIGENDUM.
Publisher: Cambridge University Press (CUP)
Date: 22-07-2019
Angiostrongylus cantonensis: a review of its distribution, molecular biology and clinical significance as a human pathogen.
Publisher: Cambridge University Press (CUP)
Date: 26-05-2016
DOI: 10.1017/S0031182016000652
Abstract: Angiostrongylus cantonensis is a metastrongyloid nematode found widely in the Asia-Pacific region, and the aetiological agent of angiostrongyliasis a disease characterized by eosinophilic meningitis. Rattus rats are definitive hosts of A. cantonensis , while intermediate hosts include terrestrial and aquatic molluscs. Humans are dead-end hosts that usually become infected upon ingestion of infected molluscs. A presumptive diagnosis is often made based on clinical features, a history of mollusc consumption, eosinophilic pleocytosis in cerebral spinal fluid, and advanced imaging such as computed tomography. Serological tests are available for angiostrongyliasis, though many tests are still under development. While there is no treatment consensus, therapy often includes a combination of anthelmintics and corticosteroids. Angiostrongyliasis is relatively rare, but is often associated with morbidity and sometimes mortality. Recent reports suggest the parasites’ range is increasing, leading to fatalities in regions previously considered Angiostrongylus -free, and sometimes, delayed diagnosis in newly invaded regions. Increased awareness of angiostrongyliasis would facilitate rapid diagnosis and improved clinical outcomes. This paper summarizes knowledge on the parasites’ life cycle, clinical aspects and epidemiology. The molecular biology of Angiostrongylus spp. is also discussed. Attention is paid to the significance of angiostrongyliasis in Australia, given the recent severe cases reported from the Sydney region.
Discovering a vaccine against neosporosis using computers: is it feasible?
Publisher: Elsevier BV
Date: 08-2014
Abstract: A vaccine is urgently needed to prevent cattle neosporosis. This infectious disease is caused by the parasite Neospora caninum, a complex biological system with multifaceted life cycles. An in silico vaccine discovery approach attempts to transform digital abstractions of this system into adequate knowledge to predict candidates. Researchers need current information to implement such an approach, such as understanding evasion mechanisms of the immune system, type of immune response to elicit, availability of data and prediction programs, and statistical models to analyze predictions. Taken together, an in silico approach involves assembly of an intricate jigsaw of interdisciplinary and interdependent knowledge. In this review, we focus on the approach influencing vaccine development against Neospora caninum, which can be generalized to other pathogenic apicomplexans.
Plasmodium falciparum Histidine-Rich Protein 2 and 3 Gene Deletions in Strains from Nigeria, Sudan, and South Sudan.
Publisher: Centers for Disease Control and Prevention (CDC)
Date: 02-2021
Application of bioinformatics to parasitology
Publisher: Elsevier BV
Date: 04-2005
In Vitro Isolation Of Neospora Caninum From A Stillborn Calf In The Uk
Publisher: Elsevier BV
Date: 08-1999
On the application of reverse vaccinology to parasitic diseases: a perspective on feature selection and ranking of vaccine candidates
Publisher: Elsevier BV
Date: 10-2017
DOI: 10.1016/J.IJPARA.2017.08.004
Abstract: Reverse vaccinology has the potential to rapidly advance vaccine development against parasites, but it is unclear which features studied in silico will advance vaccine development. Here we consider Neospora caninum which is a globally distributed protozoan parasite causing significant economic and reproductive loss to cattle industries worldwide. The aim of this study was to use a reverse vaccinology approach to compile a worthy vaccine candidate list for N. caninum, including proteins containing pathogen-associated molecular patterns to act as vaccine carriers. The in silico approach essentially involved collecting a wide range of gene and protein features from public databases or computationally predicting those for every known Neospora protein. This data collection was then analysed using an automated high-throughput process to identify candidates. The final vaccine list compiled was judged to be the optimum within the constraints of available data, current knowledge, and existing bioinformatics programs. We consider and provide some suggestions and experience on how ranking of vaccine candidate lists can be performed. This study is therefore important in that it provides a valuable resource for establishing new directions in vaccine research against neosporosis and other parasitic diseases of economic and medical importance.
Detection of Dientamoeba fragilis in fresh stool specimens using PCR
Publisher: Elsevier BV
Date: 2005
DOI: 10.1016/J.IJPARA.2004.09.003
Abstract: Dientamoeba fragilis is a trichomonad parasite that causes human gastrointestinal disease. Currently microscopy is considered to be the gold standard for diagnosis of D. fragilis infection. However, this method is time-consuming and relatively insensitive. A PCR assay based on the small-subunit ribosomal RNA gene of D. fragilis for the specific detection of D. fragilis DNA in fresh unpreserved stool s les was developed. The D. fragilis PCR was positive in 29/31 s les with positive microscopy and did not cross-react with other protozoan parasites. The PCR protocol showed a specificity of 100% and a sensitivity of 93.5% and the entire procedure can be performed in one day.
Subtype distribution of Blastocystis isolates identified in a Sydney population and pathogenic potential of Blastocystis
Publisher: Springer Science and Business Media LLC
Date: 21-09-2013
DOI: 10.1007/S10096-012-1746-Z
Abstract: Blastocystis is one of the most common enteric parasites present in humans. There is still much uncertainty about the pathogenic potential of this parasite, and it was suggested that its pathogenicity could be subtype-related. This report aimed to study 98 Blastocystis isolates found in human stool specimens to identify the subtypes present and carry out phylogenetic analysis on these isolates. This study also aimed to show the relationship between subtype and symptoms. Five-hundred and thirteen stool s les were submitted to five different diagnostic techniques for the detection of Blastocystis. Polymerase chain reaction (PCR)-positive s les were then sequenced and the small subunit (SSU) rDNA sequences were aligned and submitted to phylogenetic analysis. Ninety-eight s les were positive by any of the diagnostic methods for Blastocystis and 96 were positive by PCR. There were seven different subtypes (1, 2, 3, 4, 6, 7 and 8) identified by PCR and sequencing. This is the first large-scale study to examine the occurrence of Blastocystis in Australia. This study reports the high incidence of subtype 3 (44 %) in this population and discusses the emerging idea of subtype-dependent pathogenicity.
Populations of the south-west Pacific malaria vector Anopheles farauti s.s. revealed by ribosomal DNA transcribed spacer polymorphisms
Publisher: Springer Science and Business Media LLC
Date: 02-2000
DOI: 10.1046/J.1365-2540.2000.00665.X
Abstract: Malaria in the south-west Pacific is transmitted by members of the Anopheles punctulatus group which comprises 12 cryptic species with overlapping morphology. The most widely distributed species of the group is Anopheles farauti s.s. (An. farauti 1) found throughout northern Australia, Papua New Guinea, eastern Indonesia, the Solomon Islands and Vanuatu. A study of the population structure of this species using PCR-RFLP analysis on the ribosomal DNA internal transcribed spacer 1 reveals five genotypes which had distinct geographical distributions. Where these distributions overlap, genotype hybrids can be identified. Heteroduplex analysis of the ITS2 region reveals combinations of nonhomogenized ITS2 sequences and subsequently seven identifiable genotypes, reflecting the ITS1 distribution. Sequence analysis of these ITS2 polymorphisms reveals a minimum of 13 ITS2 sequence types present in heterogeneous combinations in in idual mosquitoes. It appears that there are different levels of evolution occurring within the ITS1 and ITS2 regions. These data suggest that An. farauti s.s. may contain multiple loci for the rDNA gene family or that the homogenization of these regions is relatively slow and can be used in genetic studies of population distribution and structure.
Compilation of parasitic immunogenic proteins from 30 years of published research using machine learning and natural language processing.
Publisher: Springer Science and Business Media LLC
Date: 20-06-2022
DOI: 10.1038/S41598-022-13790-1
Abstract: The World Health Organisation reported in 2020 that six of the top 10 sources of death in low-income countries are parasites. Parasites are microorganisms in a relationship with a larger organism, the host. They acquire all benefits at the host’s expense. A disease develops if the parasitic infection disrupts normal functioning of the host. This disruption can range from mild to severe, including death. Humans and livestock continue to be challenged by established and emerging infectious disease threats. Vaccination is the most efficient tool for preventing current and future threats. Immunogenic proteins sourced from the disease-causing parasite are worthwhile vaccine components (subunits) due to reliable safety and manufacturing capacity. Publications with ‘subunit vaccine’ in their title have accumulated to thousands over the last three decades. However, there are possibly thousands more reporting immunogenicity results without mentioning ‘subunit’ and/or ‘vaccine’. The exact number is unclear given the non-standardised keywords in publications. The study aim is to identify parasite proteins that induce a protective response in an animal model as reported in the scientific literature within the last 30 years using machine learning and natural language processing. Source code to fulfil this aim and the vaccine candidate list obtained is made available.
Autofluorescence of Toxoplasma gondii and Neospora caninum cysts in vitro
Publisher: American Society of Parasitologists
Date: 02-2005
DOI: 10.1645/GE-355R
Cyst formation and faecal-oral transmission of Dientamoeba fragilis - The missing link in the life cycle of an emerging pathogen
Publisher: Elsevier BV
Date: 10-2013
DOI: 10.1016/J.IJPARA.2013.06.003
Abstract: Dientamoeba fragilis is a protozoan parasite emerging as a cause of diarrhoea and "irritable-bowel-like" gastrointestinal disease in humans with a propensity for establishing long-term, chronic infections in humans. Although Dientamoeba was discovered over a century ago its life cycle and mode of transmission is not known. No cyst stage has been described and no animal models are presently available for the study of this parasite. Here we describe the establishment of an animal model using laboratory rodents, the fulfilling of Koch's postulates, and the discovery of a new cyst stage in the life cycle of D. fragilis. Our demonstration of long-term parasite carriage by rodents and prolonged shedding of cysts, together with elevated levels of calprotectin in the stool, confirms the capacity of this organism to cause disease and indicates dientamoebiasis should be considered in the differential diagnosis of gastrointestinal diseases such as Inflammatory Bowel Syndrome (IBS). Finally, we suggest that the cyst stage described here is the vehicle that mediates faecal-oral transmission of D. fragilis between hosts.
HAMMONDIA HEYDORNI FROM THE ARABIAN MOUNTAIN GAZELLE AND RED FOX IN SAUDI ARABIA
Publisher: American Society of Parasitologists
Date: 06-2003
Polymerase chain reaction approaches for the detection of Neospora caninum and Toxoplasma gondii
Publisher: Elsevier BV
Date: 07-1998
DOI: 10.1016/S0020-7519(98)00096-4
Abstract: This review summarizes existing knowledge on the development and use of the polymerase chain reaction for the detection of DNA from Neospora and Toxoplasma. Several strategies which utilise the polymerase chain reaction for the diagnosis of toxoplasmosis in humans and livestock have been described and they principally target the B1 repetitive sequence, the P30 gene or ribosomal DNA. Experience has shown that the polymerase chain reaction has proven insufficiently robust to serve as a diagnostic test alone although when used in conjunction with other diagnostic techniques it does prove to be a useful aid. The marketing of a commercial polymerase chain reaction kit may well solve some of the inadequacies seen using "home made" polymerase chain reaction technology which are commonly used in diagnostic laboratories around the world. Recent progress on the development of polymerase chain reaction diagnostics for Neospora has been rapid and is discussed in detail.
Microarrays and stage conversion in Toxoplasma gondii
Publisher: Elsevier BV
Date: 06-2004
Evolution of RuminantSarcocystis(Sporozoa) Parasites Based on Small Subunit rDNA Sequences
Publisher: Elsevier BV
Date: 02-1999
Abstract: We present an evolutionary analysis of 13 species of Sarcocystis, including 4 newly sequenced species with ruminants as their intermediate host, based on complete small subunit rDNA sequences. Those species with ruminants as their intermediate host form a well-supported clade, and there are at least two major clades within this group, one containing those species forming microcysts and with dogs as their definitive host and the other containing those species forming macrocysts and with cats as their definitive host. Those species with nonruminants as their intermediate host form the paraphyletic sister group to these clades. Most of the species have considerable genotypic differences (differing in more than 100 nucleotide positions), except for S. buffalonis and S. hirsuta. There is a large suite of genotypic differences indicating that those species infecting ruminant and nonruminant hosts have had very different evolutionary histories, and similarly for the felid- and canid-infecting species. Furthermore, the rDNA sequences that represent the different structural regions of the rRNA molecule have very different genotypic behavior within Sarcocystis. The evolution of these regions should be functionally constrained, and their differences can be explained in terms of the importance of the nucleotide sequences to their functions.
Gorillas are a host for Dientamoeba fragilis: An update on the life cycle and host distribution
Publisher: Elsevier BV
Date: 2008
DOI: 10.1016/J.VETPAR.2007.10.002
Abstract: Dientamoeba fragilis is a gastrointestinal protozoan that has a worldwide distribution and is emergeing as a common cause of diarrhea. As D. fragilis has a propensity to cause chronic illness with symptoms similar to irritable bowel syndrome (IBS) it is not surprising that some patients with D. fragilis are misdiagnosed as having IBS. In contrast to most other pathogenic protozoa very little is known about its life cycle, epidemiology and mode of transmission. What role animal reservoirs play in the transmission of this parasite is unknown. Consequently we undertook a prospective study to determine the host distribution of D. fragilis. Over a 2-year-period, 608 faecal s les from a wide range of animal and bird species, including pigs and other food species, were screened using permanent stained smears for the presence of D. fragilis. Trophozoites of D. fragilis were only detected in Western lowland gorillas (3/10) (Gorilla g. gorilla) and confirmed by PCR targeting the SSU rRNA gene. The limited host range detected suggests human infection may not involve transmission from other animal species. In addition, we provide an update on the limited knowledge about the life cycle of this parasite and its host distribution.
Importance of Nonenteric Protozoan Infections in Immunocompromised People
Publisher: American Society for Microbiology
Date: 10-2010
DOI: 10.1128/CMR.00001-10
Abstract: There are many neglected nonenteric protozoa able to cause serious morbidity and mortality in humans, particularly in the developing world. Diseases caused by certain protozoa are often more severe in the presence of HIV. While information regarding neglected tropical diseases caused by trypanosomatids and Plasmodium is abundant, these protozoa are often not a first consideration in Western countries where they are not endemic. As such, diagnostics may not be available in these regions. Due to global travel and immigration, this has become an increasing problem. Inversely, in certain parts of the world (particularly sub-Saharan Africa), the HIV problem is so severe that diseases like microsporidiosis and toxoplasmosis are common. In Western countries, due to the availability of highly active antiretroviral therapy (HAART), these diseases are infrequently encountered. While free-living amoebae are rarely encountered in a clinical setting, when infections do occur, they are often fatal. Rapid diagnosis and treatment are essential to the survival of patients infected with these organisms. This paper reviews information on the diagnosis and treatment of nonenteric protozoal diseases in immunocompromised people, with a focus on patients infected with HIV. The nonenteric microsporidia, some trypanosomatids, Toxoplasma spp., Neospora spp., some free-living amoebae, Plasmodium spp., and Babesia spp. are discussed.
Molecular Detection of Antimalarial Drug Resistance in Plasmodium vivax from Returned Travellers to NSW, Australia during 2008–2018
Publisher: MDPI AG
Date: 05-05-2021
Abstract: To monitor drug resistance in Plasmodium vivax, a multidrug resistance 1 (Pvmdr1) gene and a putative transporter protein (Pvcrt-o) gene were used as molecular markers for chloroquine resistance. The biomarkers, the dihydrofolate reductase (Pvdhfr) gene and the dihydropteroate synthetase (Pvdhps) gene, were also used for the detection of resistance to sulphadoxine-pyrimethamine (SP) this drug is often accidentally used to treat P. vivax infections. Clinical blood s les (n = 120) were collected from patients who had been to one of eight malaria-endemic countries and diagnosed with P. vivax infection. The chloroquine resistance marker, the Pvmdr1 gene, showed F976:L1076 mutations and L1076 mutation. A K10 insertion in the Pvcrt-o gene was also found among the s les successfully sequenced. A combination of L/I57:R58:M61:T117 mutations in the Pvdhfr gene and G383:G553 mutations in the Pvdhps gene were also observed. Mutations found in these genes indicate that drug resistance is present in these eight countries. Whether or not countries are using chloroquine to treat P. vivax, there appears to be an increase in mutation numbers in resistance gene markers. The detected changes in mutation rates of these genes do suggest that there is still a trend towards increasing P. vivax resistance to chloroquine. The presence of the mutations associated with SP resistance indicates that P. vivax has had exposure to SP and this may be a consequence of either misdiagnosis or coinfections with P. falciparum in the past.
Monophyletic origin of the genus Sauroleishmania
Publisher: Elsevier BV
Date: 10-1997
Molecular phylogeny of Besnoitia and the genetic relationships among Besnoitia of cattle, wildebeest and goats
Publisher: Elsevier BV
Date: 12-2000
Changes in the messenger RNA population during sporulation of Eimeria maxima.
Publisher: Cambridge University Press (CUP)
Date: 02-1991
DOI: 10.1017/S0031182000060273
Abstract: Messenger RNA has been extracted from oocysts of Eimeria maxima . Using the techniques of in vitro translation and SDS–polyacrylamide gel electrophoresis, we have been able to show that major changes in gene transcription occur during sporulation. Following an overall reduction in the abundance of many mRNAs, several genes identified as the result of an increase in the abundance of their transcripts, are highly expressed during the latter stages of sporulation. A study of two genes whose transcription is down-regulated has provided evidence which shows that both single copy and repetitive sequences are regulated during sporulation of the oocyst.
In vitro induction of Neospora caninum bradyzoites in vero cells reveals differential antigen expression| localization| and host-cell recognition of tachyzoites and bradyzoites
Publisher: American Society for Microbiology
Date: 2004
DOI: 10.1128/IAI.72.1.576-583.2004
Abstract: We report on an optimized method for the in vitro culture of tissue cyst-forming Neospora caninum bradyzoites in Vero cells and the separation of viable parasites from host cells. Treatment of tachyzoite-infected Vero cell cultures with 17 μM sodium nitroprusside for 8 days severely scaled down parasite proliferation, led to reduced expression of tachyzoite surface antigens, and induced the expression of the bradyzoite marker NcBAG1 and the cyst wall antigen recognized by the monoclonal antibody MAbCC2. Transmission electron microscopy demonstrated that intracellular parasites were located within parasitophorous vacuoles that were surrounded by a cyst wall-like structure, and the dense granule antigens NcGRA1, NcGRA2, and NcGRA7 were incorporated into the cyst wall. Adhesion-invasion assays employing purified tachyzoites and bradyzoites showed that tachyzoites adhered to, and invaded, Vero cells with higher efficiency than bradyzoites. However, removal of terminal sialic acid residues from either the host cell or the parasite surface increased the invasion of Vero cells by bradyzoites, but not tachyzoites.
Comparison of the patterns of codon usage and bias between Brugia, Echinococcus, Onchocerca and Schistosoma species
Publisher: Springer Science and Business Media LLC
Date: 1995
DOI: 10.1007/BF00931499
Dientamoeba fragilis, the Neglected Trichomonad of the Human Bowel
Publisher: American Society for Microbiology
Date: 07-2016
DOI: 10.1128/CMR.00076-15
Abstract: Dientamoeba fragilis is a protozoan parasite of the human bowel, commonly reported throughout the world in association with gastrointestinal symptoms. Despite its initial discovery over 100 years ago, arguably, we know less about this peculiar organism than any other pathogenic or potentially pathogenic protozoan that infects humans. The details of its life cycle and mode of transmission are not completely known, and its potential as a human pathogen is debated within the scientific community. Recently, several major advances have been made with respect to this organism's life cycle and molecular biology. While many questions remain unanswered, these and other recent advances have given rise to some intriguing new leads, which will pave the way for future research. This review encompasses a large body of knowledge generated on various aspects of D. fragilis over the last century, together with an update on the most recent developments. This includes an update on the latest diagnostic techniques and treatments, the clinical aspects of dientamoebiasis, the development of an animal model, the description of a D. fragilis cyst stage, and the sequencing of the first D. fragilis transcriptome.
Differential Gamma Interferon-and Tumor Necrosis Factor Alpha-Driven Cytokine Response Distinguishes Acute Infection of a Metatherian Host with Toxoplasma gondii and Neospora caninum
Publisher: American Society for Microbiology
Date: 06-2017
DOI: 10.1128/IAI.00173-17
Abstract: Toxoplasma gondii and Neospora caninum (both Apicomplexa) are closely related cyst-forming coccidian parasites that differ significantly in their host ranges and ability to cause disease. Unlike eutherian mammals, Australian marsupials (metatherian mammals) have long been thought to be highly susceptible to toxoplasmosis and neosporosis because of their historical isolation from the parasites. In this study, the carnivorous fat-tailed dunnart ( Sminthopsis crassicaudata ) was used as a disease model to investigate the immune response and susceptibility to infection of an Australian marsupial to T. gondii and N. caninum . The disease outcome was more severe in N. caninum -infected dunnarts than in T. gondii -infected dunnarts, as shown by the severity of clinical and histopathological features of disease and higher tissue parasite burdens in the tissues evaluated. Transcriptome sequencing (RNA-seq) of spleens from infected dunnarts and mitogen-stimulated dunnart splenocytes was used to define the cytokine repertoires. Changes in mRNA expression during the time course of infection were measured using quantitative reverse transcription-PCR (qRT-PCR) for key Th1 (gamma interferon [IFN-γ] and tumor necrosis factor alpha [TNF-α]), Th2 (interleukin 4 [IL-4] and IL-6), and Th17 (IL-17A) cytokines. The results show qualitative differences in cytokine responses by the fat-tailed dunnart to infection with N. caninum and T. gondii . Dunnarts infected with T. gondii were capable of mounting a more effective Th1 immune response than those infected with N. caninum , indicating the role of the immune response in the outcome scenarios of parasite infection in this marsupial mammal.
A new subspecies of Trypanosoma cyclops found in the Australian terrestrial leech Chtonobdella bilineata
Publisher: Cambridge University Press (CUP)
Date: 12-04-2020
Neosporosis and hammondiosis in dogs
Publisher: Wiley
Date: 05-02-2007
DOI: 10.1111/J.1748-5827.2006.00236.X
Abstract: The dog is a definitive host of the protozoan parasite Neospora caninum, and in many parts of the world, infection is relatively common as determined by serology. Reported seroprevalences usually range from 0 to 20 per cent, however, reports of clinically affected dogs are infrequent. Affected dogs are generally less than six months old and predominantly have signs of an ascending hindleg paralysis, with the associated lesions of polyradiculoneuritis and granulomatous polymyositis. Although any organ may be affected, infections are more common in the central nervous system, muscles, lungs and skin. Ante-mortem diagnosis is difficult but serology and cytology can aid diagnosis. The diagnosis can be confirmed by histology, immunohistochemistry, the use of molecular techniques on biopsy material, or on post-mortem examination. Neospora caninum oocysts are rarely found in faeces and must be differentiated from oocysts of related coccidians such as Hammondia heydorni and Toxoplasma gondii. Hammondia heydorni can cause diarrrhoea in immunosuppressed dogs. Neosporosis should be suspected in young pups with an ascending paralysis of the hindlegs. Treatment with clindamycin and potentiated sulphonamides may be useful in cases where muscular atrophy and fibrosis are absent. Feeding of raw meat is a potential risk factor for infection of dogs and should be discouraged.
Genome wide identification of mutational hotspots in the apicomplexan parasite neospora caninum and the implications for virulence
Publisher: Oxford University Press (OUP)
Date: 25-08-2018
DOI: 10.1093/GBE/EVY188
Oocysts and high seroprevalence of Neospora caninum in dogs living in remote Aboriginal communities and wild dogs in Australia
Publisher: Elsevier BV
Date: 06-2012
DOI: 10.1016/J.VETPAR.2011.12.027
Abstract: Canines are definitive hosts of Neospora caninum (Apicomplexa). For horizontal transmission from canines to occur, viable oocysts of N. caninum must occur in the environment of susceptible intermediate hosts. Canids in Australia include wild dogs and Aboriginal community dogs. Wild dogs are those dogs that are not dependent on humans for survival and consist of the dingo, feral domestic dog and their hybrid genotypes. Aboriginal community dogs are dependent on humans, domesticated and owned by a family, but are free-roaming and have free access throughout the community. In this study the extent of N. caninum infection was determined in a total of 374 dogs (75 wild dogs and 299 Aboriginal community dogs) using a combination of microscopic, molecular and serological techniques. Oocysts of N. caninum were observed in the faeces of two juvenile Aboriginal community dogs (2/132 1.5%). To estimate N. caninum prevalence, a new optimised cut-off of 18.5% inhibition for a commercial competitive ELISA was calculated using a two-graph receiver-operating characteristic (TG-ROC) analysis and IFAT as the gold standard resulting in equal sensitivity and specificity of 67.8%. Of the 263 dog sera tested the true prevalence of N. caninum antibodies was 27.0% (95% confidence limit: 10.3-44.1%). The association between the competitive ELISA results in dogs less than 12 month old and older dogs was significant (P=0.042). To our knowledge this is the first large scale parasitological survey of the Aboriginal community dogs and wild dogs from Australia. The high prevalence of N. caninum infection in Aboriginal community dogs illustrates that horizontal transmission of N. caninum is occurring in Australia. These results demonstrated that N. caninum in dogs is widespread, including the semi-arid to arid regions of north-western New South Wales and the Northern Territory. The populations of free-ranging dogs are likely to be important contributors to the sylvatic life cycle of N. caninum.
Protozoal Hepatitis Associated With Immunosuppressive Therapy In A Dog
Publisher: Wiley
Date: 03-2009
The controversies surrounding Giardia intestinalis assemblages A and B
Publisher: Elsevier BV
Date: 2021
Evaluating High-Throughput Ab Initio Gene Finders to Discover Proteins Encoded in Eukaryotic Pathogen Genomes Missed by Laboratory Techniques
Publisher: Public Library of Science (PLoS)
Date: 30-11-2012
Diversity profiling of xenic cultures of Dientamoeba fragilis following systematic antibiotic treatment and prospects for genome sequencing
Publisher: Cambridge University Press (CUP)
Date: 23-09-2019
DOI: 10.1017/S0031182019001173
Abstract: The presence of bacterial DNA in Dientamoeba fragilis DNA extracts from culture poses a substantial challenge to sequencing the D. fragilis genome. However, elimination of bacteria from D. fragilis cultures has proven difficult in the past, presumably due to its dependence on some unknown prokaryote/s. This study explored options for removal of bacteria from D. fragilis cultures and for the generation of genome sequence data from D. fragilis . DNA was extracted from human faecal s les and xenic D. fragilis cultures. Extracts were subjected to 16S ribosomal DNA bacterial ersity profiling. Xenic D. fragilis cultures were then subject to antibiotic treatment regimens that systematically removed bacterial species depending on their membrane structure (Gram-positive or Gram-negative) and aerobic requirements. The impact of these treatments on cultures was assessed by 16S licon sequencing. Prior to antibiotic treatment, the cultures were dominated by Gram-negative bacteria. Addition of meropenem to cultures eliminated anaerobic Gram-negative bacteria, but it also led to protozoan death after 5 days incubation. The seeding of meropenem resistant Klebsiella pneumoniae strain KPC-2 into cultures before treatment by meropenem prevented death of D. fragilis cells beyond this 5 day period, suggesting that one or more species of Gram-negative bacteria may be an essential nutritional requirement for D. fragilis . Gram-positive cells were completely eliminated using vancomycin without affecting trophozoite growth. Finally, this study shows that genome sequencing of D. fragilis is feasible following bacterial elimination from cultures as the result of the major advances occurring in bioinformatics. We provide evidence on this fact by successfully sequencing the D. fragilis 28S large ribosomal DNA subunit gene using culture-derived DNA.
The genus Hammondia is paraphyletic
Publisher: Cambridge University Press (CUP)
Date: 04-1999
DOI: 10.1017/S0031182098003801
Abstract: The phylogenetic relationships amongst Hammondia , Neospora and Toxoplasma were investigated by DNA sequence comparisons of the D2/D3 domain of the large subunit ribosomal DNA and the internal transcribed spacer 1. The results obtained allow us to reject the hypothesis that N. caninum and H. heydorni are the same species and show that Hammondia hammondi is probably the sister taxon to Toxoplasma gondii .
PREVALENCE OF ENTERIC PROTOZOA IN HUMAN IMMUNODEFICIENCY VIRUS (HIV)–POSITIVE AND HIV-NEGATIVE MEN WHO HAVE SEX WITH MEN FROM SYDNEY, AUSTRALIA
Publisher: American Society of Tropical Medicine and Hygiene
Date: 03-2007
Detection of Neospora caninum DNA by the polymerase chain reaction
Publisher: Elsevier BV
Date: 04-1996
DOI: 10.1016/0020-7519(96)00030-6
Abstract: Neospora caninum is a cyst-forming coccidian parasite which is now recognised as a major cause of abortion and neonatal mortality in cattle and other livestock. This study describes the primary DNA structure of the transcribed spacer region of the rDNA of N. caninum. Of importance is that the sequence data generated have been used to develop a species-specific PCR test for N. caninum DNA, which will prove valuable in epidemiology studies on neosporosis.
An empirical comparison of distance matrix techniques for estimating codon usage divergence.
Publisher: Springer Science and Business Media LLC
Date: 11-1994
DOI: 10.1007/BF00173423
Abstract: Magnetic Resonance (MR)-only radiotherapy requires geometrically accurate MR images over the full scanner Field of View (FoV). This study aimed to investigate the repeatability of distortion measurements made using a commercial large FoV phantom and analysis software and the sensitivity of these measurements to small set-up errors. Geometric distortion was measured using a commercial phantom and software with 2D and 3D acquisition sequences on three different MR scanners. Two sets of repeatability measurements were made: three scans acquired without moving the phantom between scans (single set-up) and five scans acquired with the phantom re-set up in between each scan (repeated set-up). The set-up sensitivity was assessed by scanning the phantom with an intentional 1 mm lateral offset and independently an intentional 1° rotation. The mean standard deviation of distortion for all phantom markers for the repeated set-up scans was Geometric distortion measurements using a commercial phantom and associated software appear repeatable, although with some sensitivity to set-up errors. This suggests the phantom and software are appropriate for commissioning a MR-only radiotherapy workflow.
Neospora caninum--how close are we to development of an efficacious vaccine that prevents abortion in cattle?
Publisher: Elsevier BV
Date: 09-2009
DOI: 10.1016/J.IJPARA.2009.05.007
Abstract: Neospora caninum is a protozoan parasite that causes abortion in cattle around the world. Although the clinical signs of disease in both dogs and cattle have now been recognised for over 20years, treatment and control options are still limited, despite the availability of a commercial vaccine in some countries of the world. The case for an efficacious vaccine has not been convincingly waged by farmers, veterinarians and other members of the agricultural and rural communities. In recent times, however, economic modelling has been used to estimate the industry losses due to Neospora-associated abortion, providing, in turn, the business case for forms of control for this parasite, including the development of vaccines. In this review, we document progress in all areas of the vaccine development pipeline, including live, killed and recombinant forms and the animal models available for vaccine evaluation. In addition, we summarise the main outcomes on the economics of Neospora control and suggest that the current boom in the global dairy industry increases the specific need for a vaccine against N. caninum-associated abortion.
Ribosomal DNA sequence comparison of Babesia and Theileria.
Publisher: Elsevier BV
Date: 08-1992
DOI: 10.1016/0166-6851(92)90097-4
Abstract: Previous studies on the taxonomy of Babesia spp. (phylum Apicomplexa) using morphological and life cycle characteristics have resulted in their classification into 3 subgenera, with the genus Theileria being most closely related to them. Using a strategy based on the direct sequence analysis of products derived by asymmetric PCR to determine the nucleotide sequences, we have tested the validity of this classification by sequencing the small subunit ribosomal RNA genes lified from 2 Babesia species, namely Babesia bovis and Babesia rodhaini, and comparing these with previously published sequences of Theileria annulata and Babesia bigemina using Plasmodium falciparum as an outgroup. The results of this phylogenetic analysis support the recognition of at least 2 genera in Babesia--one to include B. bigemina and B. bovis, the other to include B. rodhaini.
A case-controlled study of Dientamoeba fragilis infections in children
Publisher: Cambridge University Press (CUP)
Date: 27-04-2011
DOI: 10.1017/S0031182011000448
Abstract: Dientamoeba fragilis is a pathogenic protozoan parasite that is implicated as a cause of human diarrhoea. A case-controlled study was conducted to determine the clinical signs associated with D. fragilis infection in children presenting to a Sydney Hospital. Treatment options are also discussed. Stool specimens were collected from children aged 15 years or younger and analysed for the presence of D. fragilis . In total, 41 children were included in the study along with a control group. Laboratory diagnosis was performed by microscopy of permanently stained, fixed faecal smears and by real-time PCR. Gastrointestinal symptoms were present in 40/41 (98%) of these children with dientamoebiasis, with diarrhoea (71%) and abdominal pain (29%) the most common clinical signs. Chronic gastrointestinal symptoms were present in 2% of cases. The most common anti-microbial used for treatment was metronidazole ( n =41), with complete resolution of symptoms and clearance of parasite occurring in 85% of cases. A treatment failure rate occurred in 15% of those treated with metronidazole. Follow-up treatment comprised of an additional course of metronidazole or iodoquinol was needed in order to achieve complete resolution of infection and symptoms in this group. This study demonstrates the pathogenic potential of D. fragilis in children and as such it is recommended that all laboratories must routinely test for this organism and treat if detected.
An outbreak of abortion in a dairy herd associated with Neospora caninum and bovine pestivirus infection
Publisher: Wiley
Date: 2004
Subcellular fractionation and molecular characterization of the pellicle and plasmalemma of Neospora caninum
Publisher: Cambridge University Press (CUP)
Date: 16-06-2005
Descriptive epidemiology of infectious gastrointestinal illnesses in Sydney, Australia, 2007–2010
Publisher: World Health Organization, Western Pacific Regional Office
Date: 06-10-2015
Dynamic island model based on spectral clustering in genetic algorithm
Publisher: IEEE
Date: 05-2017
A previously unclassified trypanosomatid responsible for human cutaneous lesions in Martinique (French West Indies) is the most divergent member of the genus Leishmania ss.
Publisher: Cambridge University Press (CUP)
Date: 2002
DOI: 10.1017/S0031182001008927
Abstract: Two cases of skin lesions similar to those caused by Leishmania parasites have been reported from Martinique. Parasites isolated from these lesions were unlike Leishmania reference strains by isoenzyme analysis and electron microscopy and were assumed to be monoxenous trypanosomatids which normally only infect invertebrates. Both strains have now been retyped by isoenzyme analysis and found to be identical to each other and distantly related to all other Leishmania species. The sequence of the 18S ribosomal RNA gene and partial sequences of the DNA polymerase alpha and RNA polymerase II largest subunit genes were obtained. These sequences indicated that the Martinique parasites clustered with L. enriettii and were basal to all other euleishmania. However, support for both the position basal to all euleishmania and the clustering with L. enriettii was low. The Martinique parasites may cluster with L. ( Leishmania ) or L. ( Viannia ) or form a novel clade within the euleishmania either with or without L. enriettii .
Treatment failure in patients with chronic Blastocystis infection
Publisher: Microbiology Society
Date: 02-2014
Abstract: This article reports long-term infection and treatment failure in 18 symptomatic in iduals infected with Blastocystis spp . Patients were initially treated with either metronidazole, iodoquinol or triple combination therapy consisting of nitazoxanide, furazolidone and secnidazole. Following treatment, resolution of clinical symptoms did not occur and follow-up testing revealed ongoing infection with the same subtype. Patients then underwent secondary treatment with a variety of antimicrobial agents but remained symptomatic with Blastocystis spp. still present in faeces. Sequencing of the SSU rDNA was completed on all isolates and four subtypes were identified in this group: ST1, ST3, ST4 and ST5. This study highlights the lack of efficacy of several commonly used antimicrobial regimens in the treatment of Blastocystis and the chronic nature of some infections. It also demonstrates the need for further research into treatment options for Blastocystis infection.
Detecting sequence variants in clinically important protozoan parasites.
Publisher: Elsevier BV
Date: 2020
DOI: 10.1016/J.IJPARA.2019.10.004
Abstract: Second and third generation sequencing methods are crucial for population genetic studies, and variant detection is a popular approach for exploiting this sequence data. While mini- and microsatellites are historically useful markers for studying important Protozoa such as Toxoplasma and Plasmodium spp., detecting non-repetitive variants such as those found in genes can be fundamental to investigating a pathogen's biology. These variants, namely single nucleotide polymorphisms and insertions and deletions, can help elucidate the genetic basis of an organism's pathogenicity, identify selective pressures, and resolve phylogenetic relationships. They also have the added benefit of possessing a comparatively low mutation rate, which contributes to their stability. However, there is a plethora of variant analysis tools with nuanced pipelines and conflicting recommendations for best practise, which can be confounding. This lack of standardisation means that variant analysis requires careful parameter optimisation, an understanding of its limitations, and the availability of high quality data. This review explores the value of variant detection when applied to non-model organisms such as clinically important protozoan pathogens. The limitations of current methods are discussed, including special considerations that require the end-users' attention to ensure that the results generated are reproducible, and the biological conclusions drawn are valid.
Evolutionary Insight into the Trypanosomatidae Using Alignment-Free Phylogenomics of the Kinetoplast.
Publisher: MDPI AG
Date: 18-09-2019
Abstract: Advancements in next-generation sequencing techniques have led to a substantial increase in the genomic information available for analyses in evolutionary biology. As such, this data requires the exponential growth in bioinformatic methods and expertise required to understand such vast quantities of genomic data. Alignment-free phylogenomics offer an alternative approach for large-scale analyses that may have the potential to address these challenges. The evolutionary relationships between various species within the trypanosomatid family, specifically members belonging to the genera Leishmania and Trypanosoma have been extensively studies over the last 30 years. However, there is a need for a more exhaustive analysis of the Trypanosomatidae, summarising the evolutionary patterns amongst the entire family of these important protists. The mitochondrial DNA of the trypanosomatids, better known as the kinetoplast, represents a valuable taxonomic marker given its unique presence across all kinetoplastid protozoans. The aim of this study was to validate the reliability and robustness of alignment-free approaches for phylogenomic analyses and its applicability to reconstruct the evolutionary relationships between the trypanosomatid family. In the present study, alignment-free analyses demonstrated the strength of these methods, particularly when dealing with large datasets compared to the traditional phylogenetic approaches. We present a maxicircle genome phylogeny of 46 species spanning the trypanosomatid family, demonstrating the superiority of the maxicircle for the analysis and taxonomic resolution of the Trypanosomatidae.
A guide to current methodology and usage of reverse vaccinology towardsin silicovaccine discovery
Publisher: Oxford University Press (OUP)
Date: 20-02-2023
Abstract: Reverse vaccinology (RV) was described at its inception in 2000 as an in silico process that starts from the genomic sequence of the pathogen and ends with a list of potential protein and/or peptide candidates to be experimentally validated for vaccine development. Twenty-two years later, this process has evolved from a few steps entailing a handful of bioinformatics tools to a multitude of steps with a plethora of tools. Other in silico related processes with overlapping workflow steps have also emerged with terms such as subtractive proteomics, computational vaccinology, and immunoinformatics. From the perspective of a new RV practitioner, determining the appropriate workflow steps and bioinformatics tools can be a time consuming and overwhelming task, given the number of choices. This review presents the current understanding of RV and its usage in the research community as determined by a comprehensive survey of scientific papers published in the last seven years. We believe the current mainstream workflow steps and tools presented here will be a valuable guideline for all researchers wanting to apply an up-to-date in silico vaccine discovery process.
Contributions to the phylogeny of platyhelminthes based on partial sequencing of 18S ribosomal DNA
Publisher: Elsevier BV
Date: 09-1993
DOI: 10.1016/0020-7519(93)90067-9
Abstract: Partial sequencing of the 18S ribosomal DNA gene of one nemertean and 13 free-living and parasitic Platyhelminthes (556 nucleotides), and of one nemertean and 20 Platyhelminthes (556 nucleotides) was used to test several hypotheses concerning the phylogenetic relationships of Platyhelminthes. The following conclusions were reached: the Neodermata is monophyletic Trematoda (Aspidogastrea and Digenea) is monophyletic, although a sister group relationship of the Aspidogastrea and all other Neodermata cannot be definitely ruled out the Cestoda comprising the Eucestoda, Amphilinidea and Gyrocotylidea is monophyletic it is unresolved whether the Monogenea is paraphyletic neither Gyrocotylidea and Monopisthocotylea nor Gyrocotylidea and Monogenea as a whole are sister groups Anoplodiscus is a monopisthocotylean monogenean none of Proseriata, Pterastericolidae/Umagillidae, Kalyptorhynchia, Rhabdocoela as a whole, Dalyelliida or the Temnocephalidae is the sister group of the Neodermata there is some evidence that a larger taxon consisting of Proseriata, Tricladida and Rhabdocoela may be the sister group of the Neodermata but definitive evidence for a sister group relationship between the Neodermata and any turbellarian taxon is lacking Rhabdocoela and Lecithoepitheliata are not closely related it is unresolved whether the Rhabdocoela is monophyletic Umagillidae, Pterastericolidae and Temnocephalidae belong to one monophylum the Temnocephalidae are very close to the dalyelliids Tricladida and Rhabdocoela are sister groups, the exact position of the Catenulida and Nemertini in relation to the Platyhelminthes has not been resolved, although Catenulida and Lecithoepitheliata may belong to one clade.
Amoebiasis: current status in Australia
Publisher: AMPCo
Date: 04-2007
DOI: 10.5694/J.1326-5377.2007.TB00975.X
Abstract: Entamoeba histolytica is one of the most common parasitic infections worldwide, infecting about 50 million people and resulting in 40,000-100,000 deaths a year. In Australia, people at risk of infection include immigrants, travellers returning from countries of high endemicity, Indigenous people, and men who have sex with men. Clinical manifestations range from asymptomatic carriage to invasive disease. Amoebic colitis and amoebic liver abscess are the most common invasive manifestations observed in Australia. Diagnosis depends on a high index of suspicion and laboratory investigations. Molecular methods (using the polymerase chain reaction) are the most sensitive for identifying and differentiating Entamoeba species. Treatment should always include a luminal agent to eradicate colonisation, prevent spread and/or reduce the risk of invasive disease. Medical therapy can successfully cure invasive disease, including amoebic liver abscesses.
Implications of wild dog ecology on the sylvatic and domestic life cycle of Neospora caninum in Australia
Publisher: Elsevier BV
Date: 04-2011
DOI: 10.1016/J.TVJL.2010.03.002
Abstract: Neospora caninum is transmitted either transplacentally or horizontally by ingestion of tissue cysts present in tissues or oocysts shed by dogs. Neosporosis is a significant disease, causing cattle abortion at 5-7 months of pregnancy. Infected cows may remain infective for life transmitting the infection in several consecutive or non-consecutive pregnancies. A great deal is known about the epidemiology of neosporosis, although only limited information is available on the main routes of horizontal transmission. In Australia, the presence of the dingo as the top-order predator suggests a potential sylvatic route of transmission between dingoes and as yet unknown native wildlife in addition to the domestic route via dogs with access to infected tissue on farms. This review article critically evaluates the overlap between the domestic and sylvatic routes, taking into account canine ecology, and summarises current understanding of the transmission of N. caninum to provide a foundation for epidemiologists, farmers and conservation biologists dealing with neosporosis and wild dog control programs.
Neospora abortions in dairy cattle: diagnosis, mode of transmission and control
Publisher: Elsevier BV
Date: 03-2005
DOI: 10.1016/J.VETPAR.2004.12.012
Abstract: To determine the contribution of Neospora caninum to abortions on a dairy farm in NSW (Australia), determine the mode of transmission and develop and trial a control option for infection. Two whole herd bleeds were conducted 12 months apart and the association between serological status and abortion events were calculated for a number of bovine abortifacients. Family trees were constructed for N. caninum seropositive cattle in the herd. Some N. caninum seropositive cows were culled from the herd and no female offspring was retained from seropositive cows. At the first whole-herd bleed in December 2002 a seroprevalence of 10.2% for N. caninum infection was detected. Cows with N. caninum infection were 13 times more likely to abort than uninfected ones. Seventy-five percent of seropositive animals in the herd were related, suggesting a high degree of congenital infection/transmission. Only 15% of infections were likely to be postnatally acquired. Selective culling of seropositive cows and not breeding from them reduced the number of seropositive animals. Only one newly sero-converted cow was detected at the second whole-herd bleed 12 months later. Seroepidemiological approaches were able to establish a high degree of association between N. caninum infection and low-level abortion in the dairy herd. Vertical transmission of infection was the predominant mode of infection and hence control efforts aimed at selectively culling seropositive animals from the herd were highly successful in reducing the level of infection.
Isolation of Novel Trypanosomatid, Zelonia australiensis sp. nov. (Kinetoplastida: Trypanosomatidae) Provides Support for a Gondwanan Origin of Dixenous Parasitism in the Leishmaniinae
Publisher: Public Library of Science (PLoS)
Date: 12-01-2017
Locally acquired infection with Entamoeba histolytica in men who have sex with men in Australia
Publisher: AMPCo
Date: 10-2006
A microscopic description and ultrastructural characterisation of Dientamoeba fragilis: An emerging cause of human enteric disease
Publisher: Elsevier BV
Date: 02-2012
DOI: 10.1016/J.IJPARA.2011.10.010
Abstract: Dientamoeba fragilis is a pathogenic trichomonad found in the gastrointestinal tract of humans and is implicated as a cause of diarrhoea. Despite its discovery over a century ago, there has been no recent thorough description of this parasite by microscopy. Scanning electron microscopy, transmission electron microscopy, confocal and light microscopy were therefore used to characterise D. fragilis populations growing in xenic culture. Two different populations - smooth and ruffled cells - were identifiable by scanning electron microscopy. No flagella, pelta structures, undulating membrane or pseudocyst-like forms were present. The organelles in D. fragilis were analysed by transmission electron microscopy like Trichomonas and Histomonas, D. fragilis contains hydrogenosomes that presumably represent the site of anaerobic respiration. The nuclear morphology of D. fragilis trophozoites grown in vitro and trophozoites from clinical isolates were also compared by confocal microscopy and light microscopy. The majority of cells grown in culture were mononucleate while most cells in permanent stained faecal smears were binucleate. The two nuclei of D. fragilis are morphologically indistinguishable and contain equivalent amounts of DNA as determined by DAPI staining. The approximate cell and nuclear volume of four isolates of D. fragilis were measured and shown to be comparable to other trichomonads. In addition, the discovery of a virus-like particle is reported, to our knowledge for the first time in D. fragilis. This study therefore provides extensive and novel details of the ultrastructure of a neglected protozoan parasite that is an emerging cause of human disease.
Seroprevalence of Neospora caninum Infection Following an Abortive Outbreak in a Dairy Cattle Herd
Publisher: Wiley
Date: 04-2000
DOI: 10.1111/J.1751-0813.2000.TB11752.X
Abstract: To investigate the seroprevalence of Neospora caninum infection in a commercial dairy cattle herd, 15 months after detection of an abortion outbreak. Sera from the whole herd (n = 266) were examined for N caninum antibodies by indirect fluorescent antibody test (IFAT) and immunoblot analysis. Herd records were reviewed to collate serological results with abortion history, proximity to calving, and pedigree data. The seroprevalence of N caninum infection was 24% (63/266) for IFAT titre > or = 160, 29% (78/266) for immunoblot positive (+ve), and 31% (82/266) for IFAT > or = 160 and/or immunoblot +ve 94% (59/63) of animals with IFAT > or = 160 were immunoblot +ve. The association between seropositivity (IFAT > or = 160 and/or immunoblot +ve) and history of abortion was highly significant (P < 0.001) the seroprevalence was 86% (18/21) in aborting cows, compared with 30% (50/164) in non-aborting animals. The abortion rate for seropositive cows was 26% (18/68) compared with 3% (3/117) for seronegative animals. IFAT titres of infected cows were higher within 2 months of calving than at other times (P < 0.001). The association between seropositivity in dams and daughters was highly significant (P = 0.009). The abortions were associated with N caninum infection and there was evidence of reactivation of latent infection close to calving and congenital transmission of infection. Immunodominant antigens identified by immunoblots may prove useful for improved diagnostic tests.
A guide to in silico vaccine discovery for eukaryotic pathogens
Publisher: Oxford University Press (OUP)
Date: 24-10-2012
DOI: 10.1093/BIB/BBS066
Abstract: In this article, a framework for an in silico pipeline is presented as a guide to high-throughput vaccine candidate discovery for eukaryotic pathogens, such as helminths and protozoa. Eukaryotic pathogens are mostly parasitic and cause some of the most damaging and difficult to treat diseases in humans and livestock. Consequently, these parasitic pathogens have a significant impact on economy and human health. The pipeline is based on the principle of reverse vaccinology and is constructed from freely available bioinformatics programs. There are several successful applications of reverse vaccinology to the discovery of subunit vaccines against prokaryotic pathogens but not yet against eukaryotic pathogens. The overriding aim of the pipeline, which focuses on eukaryotic pathogens, is to generate through computational processes of elimination and evidence gathering a ranked list of proteins based on a scoring system. These proteins are either surface components of the target pathogen or are secreted by the pathogen and are of a type known to be antigenic. No perfect predictive method is yet available therefore, the highest-scoring proteins from the list require laboratory validation.
Isolation, characterization and expression of a GRA2 homologue from Neospora caninum.
Publisher: Cambridge University Press (CUP)
Date: 04-2000
DOI: 10.1017/S0031182099005673
Abstract: A cDNA library derived from mRNA of tachyzoites of Neospora caninum (NC-Liverpool strain) was screened with antisera from a cow naturally infected with N. caninum. The DNA sequence of 1 recombinant isolated predicted a significant protein sequence homology of the gene product to the 28 kDa (GRA2) antigen of Toxoplasma gondii. Studies on the N. caninum gene coding for this antigen demonstrated the presence of a single intron flanked by 2 exons the gene was also highly expressed in culture-derived tachyzoites. The antigen was expressed in Escherichia coli when injected into mice it stimulated the production of antibodies which detected a 29 kDa antigen of N. caninum. Secondary structure predictions made for the N. caninum protein showed support for several hipathic helices separated by loops and turns. The available evidence indicates maintenance of protein secondary structure, and not DNA or amino acid sequence, has occurred during the evolution of GRA2 proteins in N. caninum and T. gondii.
Comparison of Stool Antigen Detection Kits to PCR for Diagnosis of Amebiasis
Publisher: American Society for Microbiology
Date: 05-2008
DOI: 10.1128/JCM.02261-07
Abstract: The present study was conducted to compare two stool antigen detection kits with PCR for the diagnosis of Entamoeba histolytica infections by using fecal specimens submitted to the Department of Microbiology at St. Vincent's Hospital, Sydney, and the Institute of Medical and Veterinary Science, Adelaide, Australia. A total of 279 stool s les containing the E complex ( E. histolytica , Entamoeba dispar , and Entamoeba moshkovskii ) were included in this study. The stool specimens were tested by using two commercially produced enzyme immunoassays (the Entamoeba CELISA PATH and TechLab E. histolytica II kits) to detect antigens of E. histolytica . DNA was extracted from all of the s les with a Qiagen DNA stool mini kit (Qiagen, Hilden, Germany), and a PCR targeting the small-subunit ribosomal DNA was performed on all of the s les. When PCR was used as a reference standard, the CELISA PATH kit showed 28% sensitivity and 100% specificity. The TechLab ELISA (enzyme-linked immunosorbent assay) kit did not prove to be useful in detecting E. histolytica , as it failed to identify any of the E. histolytica s les which were positive by PCR. With the TechLab kit, cross-reactivity was observed for three specimens, one of which was positive for both E. dispar and E. moshkovskii while the other two s les contained E. moshkovskii . Quantitative assessment of the PCR and ELISA results obtained showed that the ELISA kits were 1,000 to 10,000 times less sensitive, and our results show that the CELISA PATH kit and the TechLab ELISA are not useful for the detection of E. histolytica in stool s les from patients in geographical regions where this parasite is not endemic.
Positive-unlabeled learning for the prediction of conformational B-cell epitopes
Publisher: Springer Science and Business Media LLC
Date: 12-2015
Species diversity and genome evolution of the pathogenic protozoan parasite, Neospora caninum.
Publisher: Elsevier BV
Date: 10-2020
Contribution of introns to the species diversity associated with the apicomplexan parasite, Neospora caninum
Publisher: Springer Science and Business Media LLC
Date: 03-01-2020
DOI: 10.1007/S00436-019-06561-X
Abstract: Neospora caninum is an intracellular parasite considered a leading cause of bovine reproduction failure worldwide, and a serious neurological disease of canines. Transplacental transmission in intermediate hosts is considered the most efficient means of transmission, which strictly involves asexual reproduction. Nonetheless, extensive genetic ersity has been reported within the species. What is yet to be elucidated are the major drivers of such ersity, and their impact on important parasite phenotypes such as virulence. Instead of protein-encoding sequences, genome and transcriptome data were used to investigate SNPs in introns between two distinct N. caninum isolates, with reported differences in pathogenicity. Variant analysis identified 840 and 501 SNPs within intergenic regions and introns, respectively, distinctly concentrated on chromosomes VI and XI, whereas the rest of the genome was monomorphic in comparison. Gene ontologies for SNP-dense intron-containing genes included ATP binding, transmembrane transport, protein kinase activity, and transcription and translation processes. This study shows that variation in non-coding DNA is contributing to N. caninum intraspecies genetic ersity, and potentially influencing and contributing to important parasite mechanisms. Finally, we present an assembled and annotated N. caninum apicoplast genome and show that this essential organelle is highly conserved between the two isolates, and related Coccidia.
Genetic Diversity Amongst Isolates Of Neospora Caninum, And The Development Of A Multiplex Assay For The Detection Of Distinct Strains
Publisher: Elsevier BV
Date: 06-2009
Subtype distribution of Blastocystis isolates from a variety of animals from New South Wales, Australia
Publisher: Elsevier BV
Date: 09-2013
DOI: 10.1016/J.VETPAR.2013.01.011
Abstract: A total of 438 stool s les from 38 different species of animal from seven different locations were studied for the presence of Blastocystis. PCR analysis was completed on all s les and DNA sequence data from the rDNA were submitted to subtype allocation. There was a total of 80 (18%) sequences from 18 species, and nine different subtypes were identified - ST1, ST2, ST3, ST4, ST5, ST7, ST11, ST12 and ST13. This is the first report of Blastocystis from the eastern grey kangaroo, red kangaroo, wallaroo, snow leopard and ostrich. This study highlights the need for further investigation into the genetic ersity of Blastocystis which could help show the zoonotic potential of Blastocystis.
A phylogenetic study of the Anopheles punctulatus group of malaria vectors comparing rDNA sequence alignments derived from the mitochondrial and nuclear small ribosomal subunits
Publisher: Elsevier BV
Date: 12-2005
DNA polymerases of parasitic protozoa.
Publisher: Elsevier BV
Date: 04-1970
Host transmission dynamics of first- and third-stage Angiostrongylus cantonensis larvae in Bullastra lessoni
Publisher: Cambridge University Press (CUP)
Date: 21-04-2022
DOI: 10.1017/S0031182022000488
Abstract: Given the importance of angiostrongyliasis as an emerging infectious disease of humans, companion animals, and wildlife, the current study focused on the transmission dynamics of first- and third-stage larvae of the parasitic nematode, Angiostrongylus cantonensis . The migration of infective larvae and their subsequent distribution within the Lymnaeidae snail, Bullastra lessoni , were investigated over time using microscopic examination of histological sections and fresh tissue. Snails were ided into four anatomical regions: (i) anterior and (ii) posterior cephalopedal masses, (iii) mantle skirt and (iv) visceral mass. The viability of free-swimming third-stage larvae, after their release from snail tissues, was evaluated in vitro by propidium iodide staining and infectivity by in vivo infection of Wistar rats. Snails were sequentially dissected over time to assess the number and anatomical distribution of larvae within each snail and hence infer their migration pathway. Herein, ongoing larval migratory activity was detected over 28 days post-infection. A comparison of infection rates and the larval distribution within the four designated snail regions demonstrated a significant relationship between anatomical region and density of infective larvae, with larvae mostly distributed in the anterior cephalopedal mass (43.6 ± 10.8%) and the mantle skirt (33.0 ± 8.8%). Propidium iodide staining showed that free-swimming third-stage larvae retained viability for between 4 and 8 weeks when stored under laboratory conditions. In contrast to viability, larval infectivity in rats remained for up to 2 weeks only. Knowledge gained from the current work could provide information on the development of new approaches to controlling the transmission of this parasite.
Prevalence of gastrointestinal pathogens in developed and developing countries: systematic review and meta-analysis
Publisher: SAGE Publications
Date: 03-2013
DOI: 10.4081/JPHR.2013.E9
Abstract: Diarrhoeal illness is a leading cause of child mortality and morbidity worldwide. There are no precise or current estimates of the types and prevalence of pathogens associated with diarrheal illnesses in developed and developing settings. This systematic review assessed data from 60 studies published in the English language from five developing regions and developed countries worldwide to provide regional estimates of enteric pathogens affecting children. The random-effect method was used to establish the weighted average prevalence of pathogens in adults and children for each region. Significantly more pathogens were reported by studies from developing regions compared with Organisation for Economic Co-operation and Development countries (P .016). The identification rates of pathogens from community based and hospital based studies were similar (58.5% and 58.1% respectively, P .619). The overall detection of enteric pathogens in developing countries was higher in adults (74.8% 95% CI 63.1-83.8%) compared with children (56.7% 95% CI 53.0-60.4%) (P .001). Rotavirus was the most frequently detected pathogen in all regions with the highest rate, 24.8% (95% CI 18.0-33.1%), detected in the developed countries. This systematic review is the first to provide an estimate of the prevalence of enteric pathogens associated with diarrhoeal illnesses in adults and children in developed and developing settings. While pathogen detection rate is greater in developing regions the consistently high prevalence of rotavirus in both developed and developing settings underscores the urgent need for access to rotavirus vaccines. Increased travel between developing and developed countries increases disease risk, and hence developed countries have a vested interest in supporting vaccine accessibility in developing settings.
The design and analysis of microarray experiments: Applications in parasitology
Publisher: Mary Ann Liebert Inc
Date: 06-2003
DOI: 10.1089/104454903767650658
Abstract: Microarray experiments can generate enormous amounts of data, but large datasets are usually inherently complex, and the relevant information they contain can be difficult to extract. For the practicing biologist, we provide an overview of what we believe to be the most important issues that need to be addressed when dealing with microarray data. In a microarray experiment we are simply trying to identify which genes are the most "interesting" in terms of our experimental question, and these will usually be those that are either overexpressed or underexpressed (upregulated or downregulated) under the experimental conditions. Analysis of the data to find these genes involves first preprocessing of the raw data for quality control, including filtering of the data (e.g., detection of outlying values) followed by standardization of the data (i.e., making the data uniformly comparable throughout the dataset). This is followed by the formal quantitative analysis of the data, which will involve either statistical hypothesis testing or multivariate pattern recognition. Statistical hypothesis testing is the usual approach to "class comparison," where several experimental groups are being directly compared. The best approach to this problem is to use analysis of variance, although issues related to multiple hypothesis testing and probability estimation still need to be evaluated. Pattern recognition can involve "class prediction," for which a range of supervised multivariate techniques are available, or "class discovery," for which an even broader range of unsupervised multivariate techniques have been developed. Each technique has its own limitations, which need to be kept in mind when making a choice from among them. To put these ideas in context, we provide a detailed examination of two specific ex les of the analysis of microarray data, both from parasitology, covering many of the most important points raised.
Updates on Parasitology and adopting a Gold Open Access model of production.
Publisher: Cambridge University Press (CUP)
Date: 26-09-2022
Phylogenetic relationships between Leishmania, Viannia and Sauroleishmania inferred from comparison of a variable domain within the RNA polymerase II largest subunit gene.
Publisher: Elsevier BV
Date: 07-1996
The development of random DNA probes specific for Aeromonas salmonicida
Publisher: Oxford University Press (OUP)
Date: 1998
DOI: 10.1046/J.1365-2672.1997.00304.X
Abstract: RAPD-PCR has been used to produce DNA probes for Aeromonas salmonicida. DNA hybridization studies showed that RAPD-PCR fragments of the same size did not necessarily hybridize to each other and therefore these sequences were not always homologous. However, a single RAPD-PCR fragment (designated 15e) was identified as being common to Aer. salmonicida. Subsequently, 15e was found to comprise five DNA fragments of similar size which differed in their nucleotide sequences. All five fragments were evaluated as DNA probes for the specific detection of Aer. salmonicida DNA: two hybridized specifically to DNA of all Aer. salmonicida isolates tested, including the four current subspecies and atypical isolates one hybridized to subspecies salmonicida, achromogenes and masoucida, but not subspecies smithia one hybridized to subspecies salmonicida and achromogenes, but not subspecies masoucida or smithia and one hybridized to subspecies salmonicida, achromogenes and smithia, but not subspecies masoucida. It is believed that these fragments could be useful as non-radioactive probes for the safe and rapid diagnosis of these fish pathogens.
Differentiation of Aeromonas genomospecies using random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR).
Publisher: Wiley
Date: 04-1996
DOI: 10.1111/J.1365-2672.1996.TB03235.X
Abstract: Random lified polymorphic DNA polymerase chain reaction (RAPD-PCR) was used to investigate the differentiation of the genus Aeromonas at the genomospecies level. Of 20 primers evaluated, six produced profiles which contained multiple bands capable of differentiating the genomospecies. These six primers were also used in RAPD-PCR analyses of clinical and environmental isolates of the different genomospecies. In most cases, each strain gave a unique fingerprint, illustrating genetic heterogeneity at the genomospecies level. However, some homogeneity in fragment sizes was seen among strains within a genomospecies which was not apparent in strains from different genomospecies. This study therefore complements and supports the current classification of Aeromonas into genomospecies. These results also show that RAPD-PCR has the potential to differentiate between the genomospecies of Aeromonas.
Molecular Detection of Neglected Tropical Diseases: The Case for Automated Near-Point-of-Care Diagnosis of Leishmaniasis.
Publisher: American Society of Tropical Medicine and Hygiene
Date: 11-01-2023
Abstract: Neglected tropical diseases affect those in poorer nations disproportionately across the globe. One ex le of these, leishmaniasis, is a debilitating and potentially fatal parasitic infection. Molecular detection of this disease can provide accurate and fast diagnosis, and with near point-of-care technologies, detection can be provided in many health-care settings. Traditionally, the perceived limitations to such detection methods have hindered their provision to resource-limited nations, but new technologies and techniques are helping to overcome these perceptions. The current pandemic offers an opportunity to maintain and develop further advances, ensuring molecular diagnostics are accessible to all.
Hammondia heydorni oocysts in the faeces of a greyhound in New Zealand
Publisher: Informa UK Limited
Date: 02-2003
DOI: 10.1080/00480169.2003.36328
Abstract: To identify oocysts found in faecal material of a greyhound. Polymerase chain reaction (PCR) and DNA sequencing were used to study genomic DNA isolated from oocysts purified from faeces of a greyhound. Database searches with the DNA sequences obtained showed they were derived from Hammondia heydorni. A species-specific PCR was developed to detect H. heydorni DNA. Light microscopy in conjunction with PCR and DNA sequencing definitively identified the presence of H. heydorni oocysts in faeces of a greyhound. This study confirms the presence of H. heydorni in New Zealand and indicates the need to correctly identify similar oocysts from dogs, rather than assume they are Neospora caninum.
Schistosoma mansoni: Patterns of codon usage and bias
Publisher: Cambridge University Press (CUP)
Date: 1995
DOI: 10.1017/S003118200008104X
Abstract: Codon usage and bias has been examined in 20 genes of Schistosoma mansoni . Significant heterogeneity was detected in the patterns of codon usage and bias among genes by metric multidimensional scaling and three general indictors of bias (GC 3S , N c and B). In keeping with observations on sporozoan parasites, codon usage bias was observed to be dependent on the overall base composition of the genes analysed, which in turn was reflected in the types of codons that were over or under-represented in the sequences.
The phylogenetic relationships of the genus Eimeria based on comparison of partial sequences of 18S rRNA
Publisher: Springer Science and Business Media LLC
Date: 1991
DOI: 10.1007/BF00012219
Redescription of Neospora caninum and its differentiation from related coccidia
Publisher: Elsevier BV
Date: 07-2002
DOI: 10.1016/S0020-7519(02)00094-2
Abstract: Neospora caninum is a protozoan parasite of animals, which before 1984 was misidentified as Toxoplasma gondii. Infection by this parasite is a major cause of abortion in cattle and causes paralysis in dogs. Since the original description of N. caninum in 1988, considerable progress has been made in the understanding of its life cycle, biology, genetics and diagnosis. In this article, the authors redescribe the parasite, distinguish it from related coccidia, and provide accession numbers to its type specimens deposited in museums.
DNA sequence analysis of the ribosomal DNA ITS2 region for the Anopheles punctulatus group of mosquitoes
Publisher: Wiley
Date: 08-1999
DOI: 10.1046/J.1365-2583.1999.83127.X
Abstract: The internal transcribed spacer 2 (ITS2) from the ribosomal DNA was sequenced and characterized for ten cryptic species in the Anopheles punctulatus group, the members of which are major vectors of malaria and filariasis in the south-west Pacific. The length of the ITS2 ranged from 549 bp to 565 bp and displayed levels of sequence variation ranging from 2.3% to 24.3% due mainly to indels of simple sequences. The GC content varied from 61.3% to 70.9%. These values were higher than those found in other cryptic species of mosquitoes and comparable only to members of the An. dirus complex suggesting a possible link between this group of Asian mosquitoes and the An. punctulatus group. Optimal and suboptimal secondary structures were investigated and revealed structures where the 5' region folded independently of the 3' region. Due to the large level of sequence variation between species, the ITS2 region proved unsuitable for phylogenetic analysis.
Comparison of microscopy, two xenic culture techniques, conventional and real-time PCR for the detection of Dientamoeba fragilis in clinical stool samples
Publisher: Springer Science and Business Media LLC
Date: 14-02-2010
DOI: 10.1007/S10096-010-0876-4
Abstract: Dientamoeba fragilis is a pathogenic protozoan parasite that is notoriously difficult to diagnose. The aim of this study was to determine the gold standard for laboratory detection of D. fragilis. A total of 650 human faecal s les were included in the study. All specimens underwent the following: microscopy using a permanent stain (modified iron-haematoxylin), culture using a modified Boeck and Drbohlav's medium (MBD) and TYGM-9, a conventional polymerase chain reaction (PCR) and a real-time PCR (RT-PCR). The overall prevalence of D. fragilis in the study population was 5.4% (35/650). RT-PCR detected 35 isolates, conventional PCR detected 15 isolates, MBD culture detected 14 isolates, TYGM-9 detected ten isolates, while microscopy detected 12 isolates. RT-PCR detected an additional 15 positive s les compared to the other diagnostic methods, all of which were confirmed by sequencing. When all methods were compared to each other, RT-PCR showed a sensitivity and specificity of 100 and 100%, conventional PCR 42.9 and 100%, MBD culture 40 and 100%, TYGM-9 culture 28.6 and 100%, and microscopy 34.3 and 99%, respectively. These results show that RT-PCR is the diagnostic method of choice for the detection of D. fragilis in clinical s les and, as such, should be considered as the gold standard for diagnosis.
Annotating the ‘hypothetical’ in hypothetical proteins: In-silico analysis of uncharacterised proteins for the Apicomplexan parasite, Neospora caninum
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.VETPAR.2018.11.015
Abstract: Neospora caninum is a parasite of veterinary and economic importance, affecting beef and dairy cattle industries globally. While this species has been recognised as a serious cause of disease in cattle and dogs for over 30 years, treatment and control options are still not available. Furthermore, whilst vaccination was identified as the most economic control strategy, vaccine discovery programs require new leads to investigate as vaccines. The current lack of gene annotation available for N. caninum, especially compared to the closely related model organism, Toxoplasma gondii, considerably hinders vaccine related research. Moreover, due to the high degree of similarity between the two organisms, a significant amount of gene annotation available for N. caninum stems from sequence homology between the species. However, there is a plethora of literature identifying conserved virulence factors between members of the Apicomplexa, which suggests that key players are contributing to successful parasite invasion, motility, and host cell attachment. In this study, bioinformatic approaches classified 125 uncharacterised proteins within the N. caninum genome, as transmembrane proteins with signal peptide sequences. Functional annotation assigned enriched gene ontologies for cell-adhesion, ATP binding, protein serine/threonine phosphatase complex, immune system process, antigen binding, and proteolysis. Additionally, 32 of these proteins were also identified as adhesins, or having adhesin-like properties, which were further characterised through the discovery of domains and gene ontology, to reveal their potential functional significance as virulence factors for N. caninum. This study identifies a new, small subset of proteins within N. caninum, that may be involved in host-cell interaction, parasite adhesion, and invasion, thereby implicating them as potential targets to exploit in the development of control options against the disease.
Isolation of Toxoplasma gondii from the brain of a dog in Australia and its biological and molecular characterization
Publisher: Elsevier BV
Date: 10-2009
DOI: 10.1016/J.VETPAR.2009.05.019
Abstract: Toxoplasma gondii was isolated from the brain of a young dog for the first time in Australia. The identity of the parasite was confirmed by PCR, Western blotting, electron microscopy and cat bioassay. Genotyping of the isolate (TgDgAu1) was determined by PCR-RFLP markers that showed it to be a Type II strain. Western blotting demonstrated the presence of IgM antibodies to T. gondii suggesting the bitch was probably infected during pregnancy and the T. gondii was transmitted to the pups congenitally. We believe this represents the first description of a natural case of congenital transmission of T. gondii in the dog.
Eimeria species: studies using rRNA and rDNA probes
Publisher: Cambridge University Press (CUP)
Date: 08-1990
DOI: 10.1017/S0031182000079671
Abstract: rRNA and a heterologous cloned rDNA probe have been used to detect the rRNA genes of Eimeria species which infe the chicken, and has allowed the isolation and preliminary characterization of cloned rDNA sequences from a genomic DNA library of Eimeria tenella . It is demonstrated that rRNA and rDNA probes can be used to identify in idual Eimeria species by the restriction fragment patterns detected after Southern hybridization. In addition, studies have shown that the large and small subunit rRNAs are expressed throughout sporulation.
Dientamoeba fragilisas a Cause of Travelers’ Diarrhea: Report of Seven Cases: Table 1
Publisher: Oxford University Press (OUP)
Date: 2007
DOI: 10.1111/J.1708-8305.2006.00100.X
Abstract: Dientamoeba fragilis is a pathogenic trichomonad parasite that causes gastrointestinal disease in humans. We report seven cases of travelers' diarrhea caused by D fragilis in patients who had traveled to overseas destinations within Asia or the Pacific which occurred over an 8-month period. Patients presented with diarrhea lasting from 5 days to over 4 weeks. Dientamoeba fragilis should be considered as a cause of diarrhea in returning travelers.
Molecular epidemiology of imported cases of leishmaniasis in Australia from 2008 to 2014
Publisher: Public Library of Science (PLoS)
Date: 03-03-2015
Production of a recombinant fusion protein of Sarcocystis tenella and evaluation of its diagnostic potential in an ELISA
Publisher: Elsevier BV
Date: 10-1996
DOI: 10.1016/S0304-4017(96)00971-5
Abstract: We have isolated a cDNA clone encoding an antigenic polypeptide of Sarcocystis tenella by screening a cystozoite-derived cDNA library in lambda gt11 with antibodies from sheep infected experimentally with S. tenella. This clone, termed STC29, was subcloned and expressed in the vector pGEX-3X as a soluble fusion protein with glutathione S-transferase having an apparent molecular mass of 46 kDa. Antibody raised against the recombinant fusion protein recognized a native polypeptide of 25 kDa in cystozoites of S. tenella. In an ELISA with sera from experimentally infected sheep, the recombinant STC29 antigen could differentiate infections with S. tenella from those with Sarcocystis arieticanis or Toxoplasma gondii. Hence, the research described here reports the identification of the first recombinant S. tenella antigen that may be useful for standardization of a serological test for the diagnosis of S.tenella infections in sheep.
Effects of sequence alignment on the phylogeny of Sarcocystis deduced from 18S rDNA sequences.
Publisher: Springer Science and Business Media LLC
Date: 1995
DOI: 10.1007/BF00931849
Abstract: Parkinson's disease (PD) is an age-associated neurodegenerative movement disorder that leads to loss of dopaminergic neurons and motor deficits. Approaches to neuroprotection and symptom management in PD include use of monoamine oxidase B (MAO-B) inhibitors. Many patients with PD also exhibit memory loss in the later stages of disease progression, which is treated with acetylcholine esterase (AChE) inhibitors. We sought to identify a dual-mechanism compound that would inhibit both MAO-B and AChE enzymes. Our screen identified a promising compound (7) with balanced MAO-B (IC
Description of Dientamoeba fragilis Cyst and Precystic Forms from Human Samples
Publisher: American Society for Microbiology
Date: 07-2014
DOI: 10.1128/JCM.00813-14
Abstract: Dientamoeba fragilis is a common enteropathogen of humans. Recently a cyst stage of the parasite was described in an animal model however, no cyst stage has been described in detail from clinical s les. We describe both cyst and precystic forms from human clinical s les.
Vacceed: a high-throughput in silico vaccine candidate discovery pipeline for eukaryotic pathogens based on reverse vaccinology
Publisher: Oxford University Press (OUP)
Date: 29-04-2014
DOI: 10.1093/BIOINFORMATICS/BTU300
Abstract: Summary: We present Vacceed, a highly configurable and scalable framework designed to automate the process of high-throughput in silico vaccine candidate discovery for eukaryotic pathogens. Given thousands of protein sequences from the target pathogen as input, the main output is a ranked list of protein candidates determined by a set of machine learning algorithms. Vacceed has the potential to save time and money by reducing the number of false candidates allocated for laboratory validation. Vacceed, if required, can also predict protein sequences from the pathogen’s genome. Availability and implementation: Vacceed is tested on Linux and can be freely downloaded from goodswe/vacceed/releases (includes a worked ex le with s le data). Vacceed User Guide can be obtained from goodswe/vacceed. Contact: John.Ellis@uts.edu.au Supplementary information: Supplementary Data are available at Bioinformatics online.
Evolutionary ARMS Race: Antimalarial Resistance Molecular Surveillance
Publisher: Elsevier BV
Date: 04-2018
Abstract: Molecular surveillance of antimalarial drug resistance markers has become an important part of resistance detection and containment. In the current climate of multidrug resistance, including resistance to the global front-line drug artemisinin, there is a consensus to upscale molecular surveillance. The most salient limitation to current surveillance efforts is that skill and infrastructure requirements preclude many regions. This includes sub-Saharan Africa, where Plasmodium falciparum is responsible for most of the global malaria disease burden. New molecular and data technologies have emerged with an emphasis on accessibility. These may allow surveillance to be conducted in broad settings where it is most needed, including at the primary healthcare level in endemic countries, and extending to the village health worker.
Evidence for a Neotropical Origin of Leishmania
Publisher: FapUNIFESP (SciELO)
Date: 08-2000
DOI: 10.1590/S0074-02762000000400021
Abstract: Contradictory biogeographic hypotheses for either a Neotropical or a Palaearctic origin of the genus Leishmania have been proposed. Hypotheses constructed on the basis of biogeographic data must be tested against an independent dataset and cannot be supported by biogeographic data alone. In the absence of a fossil record for the Leishmania these two hypotheses were tested against a combined dataset of sequences from the DNA polymerase A catalytic subunit and the RNA polymerase II largest subunit. The phylogeny obtained provided considerable support for a Neotropical origin of the genus Leishmania and leads us to reject the hypothesis for a Palaearctic origin.
Evaluation of the EasyScreen Protozoan Detection Kit for the diagnosis of Entamoeba histolytica
Publisher: Elsevier BV
Date: 06-2019
Predicting Protein Therapeutic Candidates for Bovine Babesiosis Using Secondary Structure Properties and Machine Learning
Publisher: Frontiers Media SA
Date: 23-07-2021
DOI: 10.3389/FGENE.2021.716132
Abstract: Bovine babesiosis causes significant annual global economic loss in the beef and dairy cattle industry. It is a disease instigated from infection of red blood cells by haemoprotozoan parasites of the genus Babesia in the phylum Apicomplexa. Principal species are Babesia bovis, Babesia bigemina , and Babesia ergens. There is no subunit vaccine. Potential therapeutic targets against babesiosis include members of the exportome. This study investigates the novel use of protein secondary structure characteristics and machine learning algorithms to predict exportome membership probabilities. The premise of the approach is to detect characteristic differences that can help classify one protein type from another. Structural properties such as a protein’s local conformational classification states, backbone torsion angles ϕ (phi) and ψ (psi), solvent-accessible surface area, contact number, and half-sphere exposure are explored here as potential distinguishing protein characteristics. The presented methods that exploit these structural properties via machine learning are shown to have the capacity to detect exportome from non-exportome Babesia bovis proteins with an 86–92% accuracy (based on 10-fold cross validation and independent testing). These methods are encapsulated in freely available Linux pipelines setup for automated, high-throughput processing. Furthermore, proposed therapeutic candidates for laboratory investigation are provided for B. bovis, B. bigemina , and two other haemoprotozoan species, Babesia canis , and Plasmodium falciparum.
The first report of ovine cerebral neosporosis and evaluation of Neospora caninum prevalence in sheep in New South Wales
Publisher: Elsevier BV
Date: 05-2010
DOI: 10.1016/J.VETPAR.2010.01.030
Abstract: Presence of Neospora caninum DNA was detected in the brain and spinal cord of an adult Merino sheep suspected of dying with acute non-suppurative meningoencephalitis and mild to moderate non-suppurative myelitis. The most severe neurological lesions were found in the midbrain at the rostral coliculi with moderate to severe multifocal vasculitis and gliosis. As this was the first known occurrence of cerebral disease in sheep in Australia caused by N. caninum, we surveyed sera from five sheep properties in New South Wales (NSW) to obtain information on the likely prevalence of N. caninum infection in NSW sheep flocks. Serology using a commercial indirect enzyme-linked immunosorbent assay (ELISA) revealed no N. caninum antibody-positive sheep (n=184). However an observed prevalence for N. caninum antibodies using a commercially available competitive ELISA was 2.2% (5/232). We conclude that although the diagnosis of fatal ovine cerebral neosporosis is of importance to our surveillance program for transmissible spongiform encephalopathy (TSE) exclusion, sheep in NSW are not commonly infected with N. caninum and this species likely plays only a minor role in the life cycle of this parasite in Australia.
Hammondia isolated from dogs and foxes are genetically distinct
Publisher: Cambridge University Press (CUP)
Date: 27-09-2006
Computational Antigen Discovery for Eukaryotic Pathogens Using Vacceed
Publisher: Springer US
Date: 22-12-2020
Enhancing In Silico Protein-Based Vaccine Discovery for Eukaryotic Pathogens Using Predicted Peptide-MHC Binding and Peptide Conservation Scores
Publisher: Public Library of Science (PLoS)
Date: 29-12-2014
Microarray analyses of mouse responses to infection by Neospora caninum identifies disease associated cellular pathways in the host response
Publisher: Elsevier BV
Date: 12-2010
DOI: 10.1016/J.MOLBIOPARA.2010.08.007
Abstract: Neospora caninum is a coccidian cyst-forming parasite found in a wide range of host species such as mice, dogs and cattle. The development of methods such as vaccines to prevent abortion and fetal loss due to neosporosis would be greatly assisted by further knowledge on immunity and host responses to infection. In this study we used microarray technology to investigate the protective host responses occurring at 6h post infection in the spleen of mice infected with a prototype live N. caninum vaccine. Naive non-pregnant mice were infected with the NC-Nowra isolate as such infections are known to induce protective host responses that will prevent transplacental transmission of a challenge given using pregnancy. The expression data was analysed by SAM (significance of microarrays), ANOVA and clustering methods. Gene lists were investigated for enrichment of gene ontology terms by functional annotation using hypergeometric tests. The results show that Qs and BALB/c mice infected with NC-Nowra differ in their transcriptional responses to infection and these affect a wide range of biological and molecular processes. Transcriptional changes in the Jak-STAT signaling pathway (as well as Irf and other IFN-γ regulated molecules such as GTPases) confirmed the influence of IFN-γ in the mouse response to N. caninum. Gene ontology analyses also assigned some of the molecules involved to well known disease pathways associated with cancer, Parkinson's and Alzheimer's diseases, which were linked to the cell cycle, mitochondrial electron transport chain and coupled proton transport pathways amongst others. Although infection of mice with NC-Nowra causes little or no signs of clinical disease, the molecular functions, processes and pathways identified through these studies clearly warrant further investigation for their role in the development of protective immunity as well as pathogenesis. These studies therefore provide new, exciting leads by which to study neosporosis.
Differential Ecology of Anopheles punctulatus and Three members of the Anopheles farauti Complex of Mosquitoes on Guadalcanal, Solomon Islands, Identified by PCR-RFLP Analysis
Publisher: Wiley
Date: 09-2000
DOI: 10.1046/J.1365-2915.2000.00248.X
Abstract: From a series of larval collections made across northern Guadalcanal during the dry season, October-November 1997, four members of the Anopheles punctulatus group of mosquitoes (Diptera: Culicidae) were identified using PCR-RFLP analysis. Anopheline larvae were found in 54/57 (95%) of the sites s led, comprising An. farauti Laveran sensu stricto (32 sites), An. farauti species no. 2 (39 sites), An. farauti no. 7 (36 sites) and An. punctulatus Dönitz (10 sites). Anopheles punctulatus occurred only on the coastal plain, where it was associated with the more transient sites. Anopheles farauti sensu lato was more widespread throughout the survey region, with similar proportions of all three sibling species in both transient and permanent sites. Two members of the An. farauti complex, An. farauti s.s. and species no. 2, were found in brackish water. All breeding sites of An. punctulatus were cohabited by An. farauti s.l., sometimes by all three sibling species. Anopheles farauti s.s. was the only species collected on human bait, with a much higher biting rate early in the evening (57 bites/human/hour at 18.30-20.00 hours) than later (0.8 bites/human/hour at 21.00-24.00 hours).
Entamoeba moshkovskii infections in Sydney, Australia
Publisher: Springer Science and Business Media LLC
Date: 24-10-2007
DOI: 10.1007/S10096-007-0399-9
Abstract: Entamoeba moshkovskii is considered to be a free-living ameba, which is morphologically similar, but biochemically and genetically different, to Entamoeba histolytica and Entamoeba dispar. However, recent studies have suggested that E. moshkovskii may be a "potential" pathogen, with infections giving rise to diarrhea and other intestinal disorders. Microscopy and polymerase chain reaction (PCR) targeting the 18S ribosomal (r) DNA was performed on fecal s les collected from patients presenting with diarrhea and other gastrointestinal disorders (test group), as well as fecal s les collected from healthy controls (control group). Of the 110 patients microscopically positive for the Entamoeba species, 55/110 (50%) s les were positive for E. moshkovskii in the test group of patients presenting with diarrhea. E. moshkovskii was the only pathogen detected (including bacteria or viruses) in 3/55 (5.5%) of the test group of patients presenting with diarrhea and abdominal pain. The DNA of E. moshkovskii was not detected in the fecal s les collected from the healthy controls. These results suggest that E. moshkovskii may not simply be a commensal of the human gastrointestinal tract and provides evidence for E. moshkovskii as a "potential" pathogen in the case of diarrhea and other gastrointestinal disorders. Further studies are needed to determine the role of E. moshkovskii in causing diarrheal diseases in our population.
Progress in the serodiagnosis of Neospora caninum infections of cattle.
Publisher: Elsevier BV
Date: 03-2000
DOI: 10.1016/S0169-4758(99)01604-X
Abstract: Neospora caninum is an apicomplexan protozoan that has become the focus of significant research attention worldwide. This organism infects a range of host species, including dogs, from which it was originally reported in 1984, but it is most important as a major cause of bovine abortion. As a result of the global importance of N. caninum, researchers have developed a number of serological tests to investigate the epidemiology of infection and disease. In this article, Robert Atkinson, Peter Harper, Michael Reichel and John Ellis consider progress made in the serodiagnosis of N. caninum.
Newly defined conditions for thein vitrocultivation and cryopreservation ofDientamoeba fragilis: new techniques set to fast track molecular studies on this organism
Publisher: Cambridge University Press (CUP)
Date: 08-07-2010
DOI: 10.1017/S0031182010000764
Abstract: Dientamoeba fragilis is a pathogen of the human gastrointestinal tract that is a common cause of diarrhoea. A paucity of knowledge on the in vitro cultivation and cryopreservation of Dientamoeba has meant that few studies have been conducted to investigate its biology. The objective of this study was to define, for the first time, in vitro culture conditions able to support the long-term in vitro growth of Dientamoeba . Also, we aimed to define a suitable method for cryopreserving viable Dientamoeba trophozoites. A modified BD medium, TYGM-9, Loeffler's slope medium, Robinson's medium, Medium 199, Trichosel and a Tritrichomonas fetus medium were compared, using cell counts, for their ability to support the growth of D. fragilis at various temperatures and atmospheric conditions. Loeffler's slope medium supported significantly better growth compared to other media. A temperature of 42°C and a microaerophilic atmosphere were also optimum for Dientamoeba growth. To our knowledge, this is the first study to describe and compare different culture media and conditions for the growth of clinical isolates of D. fragilis. This new technology will aid the development of diagnostics for dientamoebiasis as well as facilitate large-scale sequencing projects that will fast track molecular studies on D. fragilis .
Detection and transmission of Dientamoeba fragilis from environmental and household samples
Publisher: American Society of Tropical Medicine and Hygiene
Date: 02-2012
Control options for neospora caninum-Is there anything new or are we going backwards?
Publisher: Cambridge University Press (CUP)
Date: 25-03-2014
DOI: 10.1017/S0031182014000158
Abstract: Recent work has highlighted and enumerated the economic annual losses due to Neospora caninum abortions worldwide, which should provide strong motivation for the control of bovine neosporosis. However, with the recent withdrawal from sale of the only commercially available vaccine, control options for N. caninum have become more restricted. While researchers continue to work on developing alternative efficacious vaccines, what are the control options presently available for the cattle industries? At the practical level, recommendations for ‘Test-and-cull’, or ‘not breeding from seropositive dams’ stand diametrically opposed to alternative options put forward that suggest a primary producer is better advised to keep those cows in the herd that are already seropositive, i.e. assumed to be chronically infected, and indeed those that have already aborted once. Treatment with a coccidiostat has been recommended as the only economically viable option, yet no such treatment has gained official, regulatory approval. Dogs are central to the life cycle of N. caninum and have repeatedly been associated with infection and abortions in cattle by epidemiological studies. Knowledge and understanding of that pivotal role should be able to be put to use in control programmes. The present review canvasses the relevant literature for evidence for control options for N. caninum (some of them proven, many not) and assesses them in the light of the authors’ knowledge and experience with control of N. caninum .
The Transcriptome Sequence of Dientamoeba fragilis Offers New Biological Insights on its Metabolism, Kinome, Degradome and Potential Mechanisms of Pathogenicity
Publisher: Elsevier BV
Date: 09-2015
DOI: 10.1016/J.PROTIS.2015.06.002
Abstract: Dientamoeba fragilis is a human bowel parasite with a worldwide distribution. Dientamoeba was once described as a rare and harmless commensal though recent reports suggest it is common and potentially pathogenic. Molecular data on Dientamoeba is scarce which limits our understanding of this parasite. To address this, sequencing of the Dientamoeba transcriptome was performed. Messenger RNA was extracted from cultured Dientamoeba trophozoites originating from clinical stool specimens, and sequenced using Roche GS FLX and Illumina HiSeq technologies. In total 6,595 Dientamoeba transcripts were identified. These sequences were analysed using the BLAST2GO software suite and via BLAST comparisons to sequences available from TrichDB, GenBank, MEROPS and kinase.com. Several novel KEGG pathway maps were generated and gene ontology analysis was also performed. These results are thoroughly discussed guided by knowledge available for other related protozoa. Attention is paid to the novel biological insights afforded by this data including peptidases and kinases of Dientamoeba, as well as its metabolism, novel chemotherapeutics and possible mechanisms of pathogenicity. Currently, this work represents the largest contribution to our understanding of Dientamoeba molecular biology and also represents a major contribution to our understanding of the trichomonads generally, many of which are important pathogens of humans and animals.
The ambiguous life of Dientamoeba fragilis: the need to investigate current hypotheses on transmission?
Publisher: Cambridge University Press (CUP)
Date: 24-02-2011
DOI: 10.1017/S0031182010001733
Abstract: Dientamoeba fragilis is an inhabitant of the human bowel and is associated with gastrointestinal illness. Despite its discovery over a century ago, the details of Dientamoeba's life cycle are unclear and its mode of transmission is unknown. Several theories exist which attempt to explain how Dientamoeba may be transmitted. One theory suggests that animals are responsible for the transmission of Dientamoeba . However, reports of Dientamoeba in animals are sporadic and most are not supported by molecular evidence. Another theory suggests that Dientamoeba may be transmitted via the ova of a helminth. Given that the closest relative of Dientamoeba is transmitted via the ova of a helminth, this theory seems plausible. It has also been suggested that Dientamoeba could be transmitted directly between humans. This theory also seems plausible given that other relatives of Dientamoeba are transmitted in this way. Despite numerous investigations, Dientamoeba 's mode of transmission remains unknown. This review discusses the strengths and weaknesses of theories relating to Dientamoeba 's mode of transmission and, by doing so, indicates where gaps in current knowledge exist. Where information is lacking, suggestions are made as to how future research could improve our knowledge on the life cycle of Dientamoeba .
Genomics and its impact on parasitology and the potential for development of new parasite control methods
Publisher: Mary Ann Liebert Inc
Date: 06-2003
DOI: 10.1089/104454903767650667
Abstract: Parasitic organisms remain the scourge of the developed and underdeveloped worlds. Malaria, schistosomiasis, leishmaniasis, and trypanosomiasis, for ex le, still result in a large number of human deaths each year worldwide, while drug resistance among nematodes still poses a major problem to the livestock industries. Genome projects involving parasitic organisms are now abundant, and technologies for the investigations of the parasite transcriptome and proteome are well established. There is no doubt the era of the "omics" is with parasitology, and current trends in the discipline are addressing fundamental biological questions that can make best use of the new technologies, as well as the vast amount of new data being generated. Will this become the "golden age of molecular parasitology," leading to the control of parasitic diseases that have plagued mankind for hundreds of years? The primary aim of this paper is to review advances in the general area of parasite genomics, and to outline where the application of "omics" technologies can and have impacted on the development of new control methods for parasitic organisms.
Prospective study of the prevalence, genotyping, and clinical relevance of Dientamoeba fragilis infections in an Australian population
Publisher: American Society for Microbiology
Date: 06-2005
DOI: 10.1128/JCM.43.6.2718-2723.2005
Abstract: A prospective study was conducted over a 30-month period, in which fecal specimens from 6,750 patients were submitted to the Department of Microbiology at St. Vincent's Hospital, Sydney, Australia. Trophozoites of Dientamoeba fragilis were detected in 60 (0.9%) patients by permanent staining, and confirmation was performed by PCR. Gastrointestinal symptoms were present in all patients, with diarrhea and abdominal pain the most common symptoms. Thirty-two percent of patients presented with chronic symptoms. The average age of infected patients was 39.8 years. No correlation was found between D. fragilis and Enterobius vermicularis , a proposed vector of transmission for D. fragilis . The genetic ersity of 50 D. fragilis isolates was examined by PCR, and the PCR products were analyzed for the presence of restriction fragment length polymorphisms. These results showed no variation in the small-subunit rRNA gene and demonstrated a single genotype for all Australian isolates. This study shows the potential pathogenic properties of D. fragilis and the need for all laboratories to routinely test for this organism.
The development and evaluation of a nested PCR assay for detection of Neospora caninum and Hammondia heydorni in feral mouse tissues
Publisher: Elsevier BV
Date: 08-2008
DOI: 10.1016/J.MCP.2008.03.001
Abstract: The development of a novel nested polymerase chain reaction is described and used for detecting the presence of Neospora caninum and Hammondia heydorni DNA in DNA extracted from feral rodent tissues. A unique strategy was used for design of an assay that could be adapted for detecting DNA from more than one member of Toxoplasmatinae simultaneously with a minimal number of additional steps. The level of sensitivity described for this assay is comparable to real time-PCR and other nested PCR assays. Twenty-eight of 104 feral mice tested positive for N. caninum in at least one tissue (the brain, heart or liver) studied. In this study, eight instances are reported where the brain tested negative to N. caninum while at least one other tissue was positive. This suggests that prior studies, which screened only the brain, describe prevalence levels that are under-represented. None of 54 mouse brains tested positive for H. heydorni DNA. This suggests that mice are rarely infected by H. heydorni although this hypothesis needs to be explored further. Data obtained in the current study suggest that N. caninum is a common parasite of feral rodents which may be important in the epidemiology of the disease.
Isolation of Neospora caninum genes detected during a chronic murine infection
Publisher: Elsevier BV
Date: 2001
DOI: 10.1016/S0020-7519(00)00153-3
Abstract: In order to isolate genes coding for antigens of Neospora caninum which are recognised by the host immune system during a chronic murine infection, a cDNA library was immunoscreened with pooled sera from mice which survived three independent infections by N. caninum. Two new genes from N. caninum were isolated and expressed in Escherichia coli. The genes identified include one homologous to GRA1 of Toxoplasma gondii, plus another (NCP20) previously unknown in any taxon. Both genes encode small polypeptides which induced an IgG response in the mouse and were also recognised by IgG from a cow chronically infected with N. caninum. These results are consistent with the hypothesis that the polypeptides encoded by these genes are a target for the host immune system during chronic infections of N. caninum.
Cloning of a polymorphic DNA fragment from the genome of Leishmania donovani
Publisher: Elsevier BV
Date: 05-1989
DOI: 10.1016/0166-6851(89)90055-8
Abstract: Recombinant DNA clones, containing highly repetitive DNA sequences, have been isolated from a Leishmania donovani genomic DNA library prepared in the replacement vector lambda gt.WES.lambda B. Two clones, probably telomeric in location, have been characterised and show a restriction fragment size polymorphism. Evidence is presented which suggests that L. donovani is diploid for this cloned genomic locus.
Detection of Dientamoeba fragilis in animal faeces using species specific real time PCR assay.
Publisher: Elsevier BV
Date: 08-2016
DOI: 10.1016/J.VETPAR.2016.07.025
Abstract: Dientamoeba fragilis is a potentially pathogenic, enteric, protozoan parasite with a worldwide distribution. While clinical case reports and prevalence studies appear regularly in the scientific literature, little attention has been paid to this parasite's biology, life cycle, host range, and possible transmission routes. Overall, these aspects of Dientamoeba biology remain poorly understood at best. In this study, a total of 420 animal s les, collected from Australia, were surveyed for the presence of Dientamoeba fragilis using PCR. Several PCR assays were evaluated for sensitivity and specificity. Two previously published PCR methods demonstrated cross reactivity with other trichomonads commonly found in animal s les. Only one assay exhibited excellent specificity. Using this assay D. fragilis was detected from one dog and one cat s le. This is the first report of D. fragilis from these animals and highlights the role companion animals may play in D. fragilis transmission. This study demonstrated that some published D. fragilis molecular assays cross react with other closely related trichomonads and consequently are not suitable for animal prevalence studies.
Comparison and Recommendations for Use of Dientamoeba fragilis Real-Time PCR Assays.
Publisher: American Society for Microbiology
Date: 05-2019
DOI: 10.1128/JCM.01466-18
Abstract: Dientamoeba fragilis is a gastrointestinal trichomonad parasite whose pathogenicity is yet to be determined. The difficulty involved in microscopically diagnosing D. fragilis in feces led to the development of real-time PCR methodologies for the detection of D. fragilis in stool s les.
Neospora caninum: a cause of immune-mediated failure of pregnancy
Publisher: Elsevier BV
Date: 09-2002
DOI: 10.1016/S1471-4922(02)02324-3
Abstract: Resistance to many intracellular protozoan parasites is dependent on T helper cell 1 cytokine responses. This has important repercussions for pregnant females because strong T helper cell 1 cytokine responses are incompatible with successful pregnancy. Thus, there are two possible consequences of infection with protozoans such as Leishmania major, Plasmodium falciparum and Toxoplasma gondii during pregnancy: (1) pregnancy is compromised or (2) resistance to the parasite is compromised. The apicomplexan Neospora caninum is a parasite renowned for its association with abortion in cattle. Furthermore, a major route of transmission for this parasite is congenital. The evidence for the hypothesis that T helper cell 1 cytokines play a role in these events is reviewed here.
Current treatment options for Dientamoeba fragilis infections
Publisher: Elsevier BV
Date: 12-2012
Detection And Characterization Of DNA-polymerase-activity In Toxoplasma-gondii
Publisher: Cambridge University Press (CUP)
Date: 08-1993
DOI: 10.1017/S0031182000067238
Abstract: A DNA polymerase activity has been detected and characterized in crude extracts from tachzoites of Toxoplasma gondii . The enzyme has a sedimentation coefficient of 6·4 S, corresponding to an approximate molecular weight of 150000 assuming a globular shape. Like mammalian DNA polymerase α, the DNA polymerase of T. gondii was sensitive to N -ethylmaleimide and inhibited by high ionic strength. However, the enzyme activity was not inhibited by aphidicolin which is an inhibitor of mammalian DNA polymerases α, δ and ε and also cytosine-β-D-arabinofuranoside-5′-triphosphate which is an inhibitor of α polymerase. The activity was inhibited by 2′,3′-dideoxythymidine-5′-triphosphate which is an inhibitor of mammalian DNA polymerase β and γ. Magnesium ions (Mg 2+ ) were absolutely required for activity and its optimal concentration was 6 mM. The optimum potassium (K + ) concentration was 50 mM and a higher concentration of K + markedly inhibited the activity. Activity was optimal at pH 8. Monoclonal antibodies against human DNA polymerase did not bind to DNA polymerase of T. gondii . Thus the T. gondii enzyme differs from the human enzymes and may be a useful target for the design of toxoplasmacidal drugs.
Related Organisations
Liverpool School Of Tropical Medicine
Location: United Kingdom of Great Britain and Northern Ireland
University Of Liverpool
Location: United Kingdom of Great Britain and Northern Ireland
Related Funding Activities
Discovery Projects - Grant ID: DP180102584
Start Date: 08-2018
End Date: 12-2024
Amount: $620,056.00
Funder: Australian Research Council
View Funded ActivityLinkage Projects - Grant ID: LP0775326
Start Date: 01-2007
End Date: 12-2010
Amount: $185,334.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP1095200
Start Date: 07-2010
End Date: 06-2015
Amount: $169,000.00
Funder: Australian Research Council
View Funded Activity