ORCID Profile
0000-0003-1285-6052
Current Organisation
University of Liverpool
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Publisher: Microbiology Society
Date: 03-07-2023
Abstract: While fleas are often perceived simply as a biting nuisance and a cause of allergic dermatitis, they represent important disease vectors worldwide, especially for bacterial zoonoses such as plague (transmitted by rodent fleas) and some of the rickettsioses and bartonelloses. The cosmopolitan cat ( Ctenocephalides felis ) and dog ( Ctenocephalides canis ) fleas, as well as Ctenocephalides orientis (restricted to tropical and subtropical Asia), breed in human dwellings and are vectors of cat-scratch fever (caused by Bartonella spp.) and Rickettsia spp., including Rickettsia felis (agent of flea-borne spotted fever) and Rickettsia asembonensis , a suspected pathogen. These Rickettsia spp. are members of a phylogenetic clade known as the ‘transitional group’, which includes both human pathogens and arthropod-specific endosymbionts. The relatively depauperate flea microbiome can also contain other endosymbionts, including a erse range of Wolbachia strains. Here, we present circularized genome assemblies for two C. orientis -derived pathogens ( Bartonella clarridgeiae and R. asembonensis ) from Malaysia, a novel Wolbachia strain ( w Cori), and the C. orientis mitochondrion all were obtained by direct metagenomic sequencing of flea tissues. Moreover, we isolated two Wolbachia strains from Malaysian C. felis into tick cell culture and recovered circularized genome assemblies for both, one of which ( w CfeF) is newly sequenced. We demonstrate that the three Wolbachia strains are representatives of different major clades (‘supergroups’), two of which appear to be flea-specific. These Wolbachia genomes exhibit unique combinations of features associated with reproductive parasitism or mutualism, including prophage WO, cytoplasmic incompatibility factors and the biotin operon of obligate intracellular microbes. The first circularized assembly for R. asembonensis includes a plasmid with a markedly different structure and gene content compared to the published plasmid moreover, this novel plasmid was also detected in cat flea metagenomes from the USA. Analysis of loci under positive selection in the transitional group revealed genes involved in host–pathogen interactions that may facilitate host switching. Finally, the first B. clarridgeiae genome from Asia exhibited large-scale genome stability compared to isolates from other continents, except for SNPs in regions predicted to mediate interactions with the vertebrate host. These findings highlight the paucity of data on the genomic ersity of Ctenocephalides -associated bacteria and raise questions regarding how interactions between members of the flea microbiome might influence vector competence.
Publisher: Elsevier BV
Date: 08-2022
DOI: 10.1016/J.MICPATH.2022.105637
Abstract: Melioidosis is endemic in Southeast Asia and northern Australia. The causative agent of melioidosis is a Gram-negative bacterium, Burkholderia pseudomallei. Its invasion can be fatal if melioidosis is not treated promptly. It is intrinsically resistant to a variety of antibiotics. In this paper, we present a comprehensive overview of the current trends on melioidosis cases, treatments, B. pseudomallei virulence factors, and molecular techniques to detect the bacterium from different s les. The clinical and microbial diagnosis methods of identification and detection of B. pseudomallei are commonly used for the rapid diagnosis and typing of strains, such as polymerase chain reaction or multi-locus sequence typing. The genotyping strategies and techniques have been constantly evolving to identify genomic loci linked to or associated with this human disease. More research strategies for detecting and controlling melioidosis should be encouraged and conducted to understand the current situation. In conclusion, we review existing diagnostic methodologies for melioidosis detection and provide insights on prospective diagnostic methods for the bacterium.
Publisher: Journal of Applied Pharmaceutical Science
Date: 2019
Publisher: Japanese Society of Veterinary Science
Date: 2021
DOI: 10.1292/JVMS.20-0070
Publisher: Springer Science and Business Media LLC
Date: 27-04-2023
Publisher: Springer Science and Business Media LLC
Date: 23-07-2015
DOI: 10.1038/SREP12279
Abstract: Outbreaks involving the Asian genotype Chikungunya virus (CHIKV) caused over one million infections in the Americas recently. The outbreak was preceded by a major nationwide outbreak in the Philippines. We examined the phylogenetic and phylogeographic relationships of representative CHIKV isolates obtained from the 2012 Philippines outbreak with other CHIKV isolates collected globally. Asian CHIKV isolated from the Philippines, China, Micronesia and Caribbean regions were found closely related, herein denoted as Cosmopolitan Asian CHIKV (CACV). Three adaptive amino acid substitutions in nsP3 (D483N), E1 (P397L) and E3 (Q19R) were identified among CACV. Acquisition of the nsP3-483N mutation in Compostela Valley followed by E1-397L/E3-19R in Laguna preceded the nationwide spread in the Philippines. The China isolates possessed two of the amino acid substitutions, nsP3-D483N and E1-P397L whereas the Micronesian and Caribbean CHIKV inherited all the three amino acid substitutions. The unique amino acid substitutions observed among the isolates suggest multiple independent virus dissemination events. The possible biological importance of the specific genetic signatures associated with the rapid global of the virus is not known and warrant future in-depth study and epidemiological follow-up. Molecular evidence, however, supports the Philippines outbreak as the possible origin of the CACV.
Publisher: Systematic and Applied Acarology Society
Date: 27-07-2018
DOI: 10.11158/SAA.23.8.4
Abstract: Ticks are important vectors that transmit a variety of pathogenic microorganisms known to be medically important worldwide. Many vertebrate groups have become host to this organism, and their presence and abundance are an indicator of the condition of both host and its habitat. This study was conducted to determine tick’s infestation and its prevalence on small mammal’s residing in the recreational forests (RF) and semi-urban (SU) residential areas which have encountered Leptospirosis outbreak and cases in Hulu Langat, Selangor Malaysia. Trapping of the small mammals involved deploying two hundred cage traps in a systematic one-hectare plot (100 m x 100 m), as well as along the stream and forest trails at random. Ticks were extracted from the captured in idual hosts. Identification of the tick species was performed based on morphological features and molecular approach using 16S rDNA and COI (cytochrome oxidase subunit I) genes. A total of 278 in iduals of small mammals belonging to 15 species (13 Rodentia, 1 Scandentia and 1 Insectivora) were captured in the study areas. From these, 34 in iduals from eight small mammal species were infested with ticks. The most infested host species was Muller’s giant Sunda rat (Sundamys muelleri) with 5.80% (n=16). Ticks prevalence was slightly higher in RF with 6.40% (n=18) compared to SU with 5.80% (n=16). A total of 107 adult ticks (103 female and 4 male) were collected from the infested host. Ixodes granulatus was the most dominant tick species encountered (70.40%, n=85), followed by Dermacentor sp. (18.60%, n=20), while Amblyomma sp. was the least abundant (2%, n=2). This study provides information on tick species present and tick burden on small mammal hosts within the study areas. Our findings suggest that the visitors to the recreational forests and the residents of the semi-urban area were not only exposed to Leptospirosis bacteria but also tick bites and potentially tick-borne disease, therefore, precaution should be taken to avoid contact with small mammal hosts.
Publisher: Systematic and Applied Acarology Society
Date: 11-2019
Abstract: Piroplasmic parasites such as Theileria and Babesia commonly infect important livestock animals, leading to economic losses in the livestock industry. These parasites are primarily transmitted by ticks found infesting livestock animals. In Malaysia, livestock diseases caused by tick-borne pathogens are still under-studied, even though tick infestations are common in many livestock farms. Here, we molecularly detect a Theileria sp. from Haemaphysalis bispinosa ticks infesting goats in a privately-owned farm in Perak, peninsular Malaysia. PCR was performed on the DNA extracted from ticks to determine the presence of piroplasms. Three ticks were found PCR-positive for piroplasms. Sequence analyses of partial 18S rRNA gene sequences revealed the presence of a Theileria species at 100% identity to Theileria luwenshuni. Our findings suggest the presence of T. luwenshuni, a highly pathogenic Theileria sp. to sheep and goats, in the small ruminant industry in Malaysia.
Publisher: Wiley
Date: 12-02-2013
DOI: 10.1038/ICB.2013.7
Abstract: The innate immune response to virus must be balanced to eliminate infection yet limit damaging inflammation. A critical arm of the antiviral response is launched by the retinoic acid-inducible-gene I (RIG-I) protein. RIG-I is activated by viral RNA then associates with the mitochondrial antiviral signaling (MAVS) protein to subsequently induce potent inflammatory cytokines. Here, we demonstrate the mitochondrial E3 ubiquitin protein ligase 1 (MUL1) is a crucial moderator of RIG-I signaling. MUL1 is localized to the mitochondria where it interacts with MAVS and catalyzes RIG-I post-translational modifications that inhibit RIG-I-dependent cell signaling. Accordingly, depletion of MUL1 potentiated RIG-I mediated nuclear factor-kappa B (NF-κB) and interferon (IFN) β reporter activity. Moreover, depletion of MUL1 boosted the antiviral response and increased proinflammatory cytokines following challenge with the RNA mimetic poly I:C and Sendai virus. We therefore submit that MUL1 is a novel regulator of the RIG-I-like receptor-dependent antiviral response, that otherwise functions to limit inflammation.
Publisher: Systematic and Applied Acarology Society
Date: 12-03-2018
DOI: 10.11158/SAA.23.4.2
Abstract: Wild rodents are carriers of ectoparasites such as ticks that are vectors of infectious diseases with human and veterinary significances. Due to their close association with human dwellings, synanthropic wild rodents may aid the spread and transmission of tick-borne pathogens. In light of this, an effort was initiated to study the cultivable bacteria within ticks collected from wild rodents trapped in Sungai Congkak Recreational Forest, Selangor. Ticks collected from four different rodent species Sundamys muelleri, Maxomys whiteheadi, Maxomys rajah and Rattus rattus, were sterilely homogenized and cultured. One unique bacterial isolate originating from an engorged adult female Ixodes granulatus Supino collected off a Sundamys muelleri rat was identified as Paenibacilus lautus via 16S rDNA, ctpA sequencing and biochemical tests. Antimicrobial susceptibility testing revealed that the P. lautus isolate was resistant to icillin, penicillin, clindamycin, chlor henicol, rif icin and trimethoprim-sulfamethoxazole, mirroring the antimicrobial susceptibility profiles of clinical strains. Recovery of this opportunistic bacterial pathogen from the tick suggests that it may be transmitted to humans or other hosts through tick bites and cause disease once it enters the bloodstream. Therefore, it is important to remain vigilant due to its pathogenic potential and improve our waste disposal practices to avoid attracting rodents.
Publisher: Japanese Society of Veterinary Science
Date: 2022
DOI: 10.1292/JVMS.22-0037
Publisher: Systematic and Applied Acarology Society
Date: 17-09-2018
DOI: 10.11158/SAA.23.9.10
Abstract: Ticks are vectors for a number of important human and animal pathogens. In this study, Corynebacterium lactis was isolated from Amblyomma testudinarium Koch tick s led from wild boar in Malaysia. Imaging with transmission electron microscope and complete genome sequencing were performed for C. lactis which shared similar morphology to other Corynebacterium species and was susceptible to most of the commonly used antibiotics. The draft genome revealed a total length of 2,568,615 bp with G+C content of 64.3%. This is the first description of C. lactis isolation from ticks, raising the possibility that ticks could be a vector for this emerging pathogen of companion animals.
Publisher: MDPI AG
Date: 23-09-2022
DOI: 10.3390/PATHOGENS11101087
Abstract: Chigger mites are vectors of the bacterial disease scrub typhus, caused by Orientia spp. The bacterium is vertically transmitted in the vector and horizontally transmitted to terrestrial vertebrates (primarily wild small mammals), with humans as incidental hosts. Previous studies have shown that the size of the chigger populations is correlated with the density of small mammals in scrub typhus-endemic regions. Here, we explore interactions between the small mammals and chiggers in two oil palm plantations located in the Perak and Johor states of Peninsular Malaysia. The location in Perak also contained an aboriginal (Orang Asli) settlement. A ~5% sub-s le from 40,736 chigger specimens was identified from five species of small mammals (n = 217), revealing 14 chigger species, including two new records for Malaysia. The abundance and species richness of chiggers were significantly affected by habitat type (highest in forest border), state (highest in Perak), and season (highest in dry). The overall prevalence of Orientia tsutsugamushi DNA in small-mammal tissues was 11.7% and was not significantly affected by host or habitat characteristics, but in Johor, was positively associated with infestation by Leptotrombidium arenicola. These findings highlight the risk of contracting scrub typhus in oil palm plantations and associated human settlements.
Publisher: Elsevier BV
Date: 02-2020
DOI: 10.1016/J.ACTATROPICA.2019.105282
Abstract: Rickettsioses are emerging, and re-emerging diseases caused by obligate intracellular arthropod-borne bacteria that infect humans and animals worldwide. Various rickettsiae such as Orientia, Rickettsia, Anaplasma and Ehrlichia have been circulated in companion, domesticated and wild animals through bites of infected ticks, fleas, lice or mites. This review summarizes the infections of rickettsiae, including the newly discovered regional species Rickettsia thailandii, Candidatus Rickettsia sepangensis, Candidatus Rickettsia johorensis, Candidatus Rickettsia laoensis, Candidatus Rickettsia mahosotii, Candidatus Rickettsia khammouanensis, Candidatus Anaplasma pangolinii, and other novel genotypes in vectors, humans and animals in Southeast Asia. Issues on some unidentified rickettsiae that elicit immune responses and production of antibodies that are cross-reactive with the antigens used are discussed. Knowledge gaps which required attention are also identified in this review.
Publisher: Mary Ann Liebert Inc
Date: 12-2016
Publisher: Elsevier BV
Date: 03-2020
DOI: 10.1016/J.TTBDIS.2019.101352
Abstract: Ticks are hematophagous vectors of arthropod-borne disease agents globally. In Malaysia, despite seroprevalence studies indicating the presence of tick-borne diseases among the indigenous people, the etiological agents of these diseases are still unclear. These indigenous people, also known as the Orang Asli, still live in forested areas with frequent contact with wildlife. Wild boar are ubiquitously found in the forested areas where the Orang Asli communities are located and are commonly hunted as a food supplement. In this study, we aim to determine the tick species parasitizing wild boar from an Orang Asli community, and explore the tick-associated bacterial communities using 16 s rRNA licon sequencing on the Ion Torrent PGM™ platform. A total of 72 ticks were collected from three wild boar and were morphologically identified as Haemaphysalis hystricis (n = 32), Dermacentor compactus (n = 15), Amblyomma testudinarium (n = 13), Dermacentor steini (n = 10) and Dermacentor atrosignatus (n = 2). Across all tick s les, 910 bacterial taxa were identified. Although the bacterial communities were not significantly distinct between tick species in beta- ersity analyses, Coxiella, Rickettsia and Francisella were detected at high relative abundance in H. hystricis, D. compactus and D. steini respectively. Many other bacterial genera, including those that have been described in many different tick species, were also identified, including Pseudomonas, Acinetobacter, Staphylococcus and Corynebacterium. Beta- ersity analyses also showed that the bacterial communities were separated based on the animal host from which the ticks were collected from, suggesting that the bacterial communities here may be influenced by the animal skin microflora, host blood or the environment. PCR screening confirmed the presence of Rickettsia sp. related to spotted fever group Rickettsia in some of the ticks. This study provides baseline knowledge of the microbiome of H. hystricis, D. atrosignatus, D. compactus, D. steini and A. testudinarium parasitizing wild boar in this region. The information gained in this study provides the basis to target our efforts in H. hystricis, D. compactus and D. steini for the future investigation of vector competence and the zoonotic potential for the Coxiella, Rickettsia and Francisella detected here, as well as their implications for the risks of tick-borne diseases among the Orang Asli communities.
Publisher: American Society of Tropical Medicine and Hygiene
Date: 17-08-2022
Abstract: In recent years, the number of leptospirosis cases, including the number of deaths, has exponentially increased in Malaysia. From June 2016 to February 2018, blood s les of 321 febrile patients with the presumptive diagnosis of dengue-like illness were examined for possible exposure to Leptospira . Two hundred fifty-five blood s les were tested as negative for dengue. Seminested polymerase chain reaction (PCR) and IgM ELISA for leptospirosis were performed. From the s les, an overall prevalence for leptospirosis based on PCR of 4.7% (12/255) was obtained. Eighteen percent (46/255) were positive for anti- Leptospira IgM antibodies. The genome sequences of six of 12 Leptospira PCR-positive s les showed 97.0% similarity to Leptospira interrogans . One patient’s s le consisted of Leptospira and chikungunya virus, suggesting a coinfection. Findings from the study suggest that leptospirosis is prevalent among dengue-negative febrile patients in Malaysia.
Publisher: MDPI AG
Date: 07-2020
DOI: 10.3390/MICROORGANISMS8070988
Abstract: Wolbachia are intracellular endosymbionts of several invertebrate taxa, including insects and nematodes. Although Wolbachia DNA has been detected in ticks, its presence is generally associated with parasitism by insects. To determine whether or not Wolbachia can infect and grow in tick cells, cell lines from three tick species, Ixodes scapularis, Ixodes ricinus and Rhipicephalus microplus, were inoculated with Wolbachia strains wStri and wAlbB isolated from mosquito cell lines. Homogenates prepared from fleas collected from cats in Malaysia were inoculated into an I. scapularis cell line. Bacterial growth and identity were monitored by microscopy and PCR lification and sequencing of fragments of Wolbachia genes. The wStri strain infected Ixodes spp. cells and was maintained through 29 passages. The wAlbB strain successfully infected Ixodes spp. and R. microplus cells and was maintained through 2–5 passages. A novel strain of Wolbachia belonging to the supergroup F, designated wCfeF, was isolated in I. scapularis cells from a pool of Ctenocephalides sp. cat fleas and maintained in vitro through two passages over nine months. This is the first confirmed isolation of a Wolbachia strain from a flea and the first isolation of any Wolbachia strain outside the “pandemic” A and B supergroups. The study demonstrates that tick cells can host multiple Wolbachia strains, and can be added to panels of insect cell lines to improve success rates in isolation of field strains of Wolbachia.
Publisher: MDPI AG
Date: 19-01-2023
DOI: 10.3390/TROPICALMED8020074
Abstract: Many human clinical cases attributed to vector-borne pathogens are underreported in Malaysia, especially in rural localities where healthcare infrastructures are lacking. Here, 217 small mammals, consisting of rodents and tree shrews, were trapped in oil palm plantations in the Peninsular Malaysia states of Johor and Perak. Species identification was performed using morphological and DNA barcoding analyses, and 203 small mammals were included in the detection of selected vector-borne bacteria. The DNA extracted from the spleens was examined for Orientia tsutsugamushi, Borrelia spp., Bartonella spp. and Rickettsia spp. using established PCR assays. The small mammals collected in this study included Rattus tanezumi R3 mitotype (n = 113), Rattus argentiventer (n = 24), Rattus tiomanicus (n = 22), Rattus exulans (n = 17), Rattus tanezumi sensu stricto (n = 1) and Tupaia glis (n = 40). Orientia tsutsugamushi, Borrelia spp. and Bartonella phoceensis were detected in the small mammals with the respective detection rates of 12.3%, 5.9% and 4.9%. Rickettsia spp., however, was not detected. This study encountered the presence of both Lyme disease and relapsing fever-related borreliae in small mammals collected from the oil palm plantation study sites. All three microorganisms (Orientia tsutsugamushi, Borrelia spp. and Bartonella phoceensis) were detected in the R. tanezumi R3 mitotype, suggesting that the species is a competent host for multiple microorganisms. Further investigations are warranted to elucidate the relationships between the ectoparasites, the small mammals and the respective pathogens.
Publisher: Wiley
Date: 18-12-2019
DOI: 10.1002/JMV.25649
Abstract: Dengue virus (DENV), Japanese encephalitis virus (JEV), and Zika virus (ZIKV) are mosquito-borne flavivirus of medical importance in tropical countries such as Malaysia. However, much remains unknown regarding their prevalence among the underserved indigenous people (Orang Asli) living in communities in the forest fringe areas of Peninsular Malaysia. Information on the prevalence of diseases is necessary to elevate the effectiveness of disease control and preventive measures. This study aimed to determine the seroprevalence of the three major flaviviruses among the Orang Asli and investigate the association between demographic factors and seropositivities. S ling activities were conducted in the Orang Asli villages to obtain serum s les and demographic data from consenting volunteers. The presence of DENV, JEV, and ZIKV immunoglobulin G (IgG) antibodies in the sera were examined using commercial enzyme-linked immunosorbent assay kits. A focus reduction neutralization assay was performed to measure virus-specific neutralizing antibodies. A total of 872 serum s les were obtained from the Orang Asli volunteers. Serological assay results revealed that DENV IgG, JEV IgG, and ZIKV IgG seropositivities among the Orang Asli were at 4.9%, 48.4%, and 13.2%, respectively. Neutralizing antibodies (FRNT50 ≥ 1:40) against JEV and ZIKV were found in 86.7% and 100.0%, respectively, out of the s les tested. Positive serology to all three viruses corresponded significantly to the age of the volunteers with increasing seropositivity in older volunteers. Findings from the study suggest that Orang Asli are at significant risk of contracting JEV and ZIKV infections despite the lack of active transmission of the viruses in the country.
Publisher: Centers for Disease Control and Prevention (CDC)
Date: 02-2023
Publisher: Elsevier BV
Date: 02-2021
Publisher: Mary Ann Liebert Inc
Date: 03-2018
Abstract: Q fever is a disease caused by Coxiella burnetii. It is a disease of public health concern in many parts of the world. In this study, we described the seroprevalence of Q fever among selected populations of Orang Asli (OA), indigenous people, many of whom live within the forest fringe areas of Peninsular Malaysia. Serum s les were obtained from 887 OA participants from selected villages. S les were analyzed for the presence of IgG antibodies reactive against C. burnetii by enzyme-linked immunosorbent assay. Statistical methods were used to identify possible associations between seropositivity for C. burnetii and a number of demographic variables obtained from the questionnaires. In total, 9.6% (n = 85/887) of the serum s les were reactive to C. burnetii. Statistical results suggest that elderly male OA residing in OA village, Bukit Payung, were most likely to be tested seropositive for C. burnetii. This study suggests that OA are at a significant risk of contracting C. burnetii infection, and both demographic and geographic factors are important contributors to this risk. Further prospective studies are needed to establish the true burden of C. burnetii infection within the indigenous population as well as within Peninsular Malaysia as a whole.
Publisher: Journal of Infection in Developing Countries
Date: 31-05-2019
DOI: 10.3855/JIDC.11001
Abstract: Introduction: Lyme disease has been well-described in the North America and European countries. However, information is still very limited in the developing countries including Malaysia. The Orang Asli (OA), the indigenous people of Peninsular Malaysia reside mostly in the forest and forest fringe areas abundant with the vector for Lyme disease. Here, we described the seroprevalence of Borellia burgdorferi (B. burgdorferi) among the OA and demographic variables that could be associated with seroprevalence. Methodology: A total of 16 OA villages distributed across 8 states in Peninsular Malaysia participated in this study. Sera obtained from 904 OA volunteers were screened for anti-B. burgdorferi IgG antibodies. ELISA results obtained and demographic information collected were analysed to identify possible variables associated with seroprevalence. Results: A total of 73 (8.1%) OA tested positive for anti-B. burgdorferi IgG antibodies. Among all the variables examined, village of residence (p = 0.045) was the only significant predictor for seropositivity. High ( 10.0%) prevalence was associated with three OA villages. Those living in one particular village were 1.65 times more likely to be seropositive as compared to other OA villages. Age, gender, marital status, household size, level of education, monthly household income and occupation were not significant predictors for seropositivity. Conclusion: Results of the present study support earlier findings that B. burgdorferi infection among Malaysians is currently under-recognized. Further studies will be needed at these locations to confirm the presence of Lyme disease among these populations.
Publisher: MDPI AG
Date: 25-05-2022
DOI: 10.3390/MICROORGANISMS10061086
Abstract: Tick cell lines are important tools for research on ticks and the pathogens they transmit. Here, we report the establishment of ten new cell lines from European ticks of the genera Argas, Dermacentor, Hyalomma, Ixodes and Rhipicephalus originating from Germany and Spain. For each cell line, the method used to generate the primary culture, a morphological description of the cells and species confirmation by sequencing of the partial 16S rRNA gene are presented. Further molecular analysis of the two new Ixodes ricinus cell lines and three existing cell lines of the same species revealed genetic variation between cell lines derived from ticks collected in the same or nearby locations. Collectively, these new cell lines will support research into a wide range of viral, bacterial and protozoal tick-borne diseases prevalent in Europe.
Publisher: IEEE
Date: 10-2018
Publisher: Elsevier BV
Date: 07-2016
DOI: 10.1016/J.TTBDIS.2016.04.013
Abstract: Ticks are vectors in the transmission of many important infectious diseases in human and animals. Ticks can be readily found in the semi-forested areas such as the settlements of the indigenous people in Malaysia, the Orang Asli. There is still minimal information available on the bacterial agents associated with ticks found in Malaysia. We performed a survey of the bacterial communities associated with ticks collected from domestic animals found in two Orang Asli villages in Malaysia. We collected 62 ticks, microscopically and molecularly identified as related to Haemaphysalis wellingtoni, Haemaphysalis hystricis and Haemaphysalis bispinosa. Bacterial 16s rRNA hypervariable region (V6) licon libraries prepared from the tick s les were sequenced on the Ion Torrent PGM platform. We detected a total of 392 possible bacterial genera after pooling and sequencing 20 s les, indicating a erse bacterial community profile. Dominant taxa include the potential tick endosymbiont, Coxiella. Other dominant taxa include the tick-associated pathogen, Rickettsia, and environmental bacteria such as Bacillus, Mycobacterium, Sphingomonas and Pseudomonas. Other known tick-associated bacteria were also detected, including Anaplasma, Ehrlichia, Rickettsiella and Wolbachia, albeit at very low abundance. Specific PCR was performed on selected s les to identify Rickettsia and Coxiella. Sequence of Rickettsia felis, which causes spotted fever in human and cats, was identified in one s le. Coxiella endosymbionts were detected in three s les. This study provides the baseline knowledge of the microbiome of ticks in Malaysia, focusing on tick-associated bacteria affecting the Orang Asli communities. The role of the herein found Coxiella and Rickettsia in tick physiology or disease transmission merits further investigation.
Publisher: Cold Spring Harbor Laboratory
Date: 06-02-2023
DOI: 10.1101/2023.02.06.527313
Abstract: While fleas are often perceived simply as a biting nuisance and cause of allergic dermatitis, they represent important disease vectors worldwide, especially for bacterial zoonoses such as plague (transmitted by rodent fleas) and some of the rickettsioses and bartonelloses. The cosmopolitan cat ( Ctenocephalides felis ) and dog ( C. canis ) fleas, as well as C. orientis (restricted to tropical and subtropical Asia), breed in human dwellings and are vectors of cat-scratch fever (caused by Bartonella spp.) and Rickettsia spp. of the so-called "transitional group". The latter includes R. felis (agent of flea-borne spotted fever) and R. asembonensis , an emerging pathogen. The relatively depauperate flea microbiome can also contain arthropod-specific endosymbionts, including a erse range of Wolbachia strains. Here, we present circularized genome assemblies for two C. orientis -associated pathogens ( Bartonella clarridgeiae and R. asembonensis ) from Malaysia, a novel Wolbachia strain ( w Cori), and the C. orientis mitochondrion all obtained by direct metagenomic sequencing of flea tissues. Moreover, we isolated two Wolbachia strains from Malaysian C. felis into tick cell culture and recovered circularized genome assemblies for both, one of which ( w CfeF) is newly sequenced. We demonstrate that the three Wolbachia strains are representatives of different major clades ("supergroups"), two of which appear to be flea-specific. These Wolbachia genomes exhibit unique combinations of features associated with reproductive parasitism or mutualism, including prophage WO, cytoplasmic incompatibility factors, and the biotin operon of obligate intracellular microbes. The first circularized assembly for R. asembonensis includes a plasmid with a markedly different structure and gene content compared to the published plasmid moreover, this novel plasmid was also detected in cat flea metagenomes from the US. Analysis of loci under positive selection in the transitional group revealed genes involved in host-pathogen interactions that may facilitate host switching. Finally, the first B. clarridgeiae genome from Asia exhibited largescale genome stability compared to isolates from other continents, except for SNPs in regions predicted to mediate interactions with the vertebrate host. These findings highlight the paucity of data on the genomic ersity of Ctenocephalides -associated bacteria and raise questions regarding how interactions between members of the flea microbiome might influence vector competence.
Publisher: Systematic and Applied Acarology Society
Date: 03-02-2017
DOI: 10.11158/SAA.22.3.1
Abstract: Tick cell cultures have been widely used as an important tool for the study of tick-associated microorganisms, specifically for medically important bacteria or viruses that may be difficult to isolate or culture in axenic conditions. In this study, primary embryonic tick cell cultures were initiated separately from each of the egg batches laid by 10 female ticks belonging to the hard tick genus Haemaphysalis. All cultures were maintained at 28°C. After 10 months, 4 healthy cultures were identified with the potential for developing into continuous tick cell lines. These cultures comprise large cells predominantly forming floating cell clumps with multicellular vesicles, which are morphologically similar to cell lines derived from the soft tick Ornithodoros moubata. Subculture has not yet been performed due to the low cell density at the time of writing. Amplification and sequencing of a fragment of the 16S rRNA gene from DNA extracted from the parent ticks showed 99%-100% similarity to published sequences of Haemaphysalis bispinosa. This is the first report of the initiation of embryonic cell cultures from Haemaphysalis ticks found in Malaysia. Such tick cell cultures will be useful for studies of tick-borne pathogens in this region, where recent studies have shown that Haemaphysalis ticks are highly represented and harbor medically important bacteria.
Publisher: Oxford University Press (OUP)
Date: 17-08-2018
DOI: 10.1093/JME/TJY122
Abstract: The Borrelia genus consists of spirochete bacteria known to cause Lyme disease (LD) and relapsing fever in humans. Borrelia pathogens are commonly transmitted via arthropod vectors such as ticks, mites, or lice. Here, we report the molecular screening of LD group Borrelia sp. from ticks (Acari: Ixodidae) collected from rodents trapped in recreational forests and a semiurban residential area in the Selangor state in Malaysia. Of 156 adult ticks surveyed, 72 ticks were determined as positive for Borrelia sp. by polymerase chain reaction (PCR). All Borrelia PCR-positive ticks belonged to the Ixodes granulatus Supino species. Borrelia sp. was not detected in other tick species examined, including Dermacentor sp. and Amblyomma sp. ticks. Thirteen Borrelia PCR-positive tick s les were selected for further sequence analyses. Phylogenetic analyses of partial flaB gene sequences revealed that the Borrelia sp. were closely related to the LD group borreliae, Borrelia yangtzensis a novel Borrelia genospecies reported in East Asian countries including Japan, Taiwan, and China. To our knowledge, this is the first report of Borrelia sp. related to Borrelia yangtzensis detected in Malaysia and Southeast Asia. The zoonotic potential of the Borrelia sp. reported here merits further investigation, as it may explain the previously reported serological evidence for borrelial infections in Malaysia.
Publisher: Journal of Pure and Applied Microbiology
Date: 30-09-2017
Publisher: Oxford University Press (OUP)
Date: 13-07-2017
DOI: 10.1093/JME/TJX131
Abstract: Spirochetes from the Borrelia genus are known to cause diseases in humans, namely Lyme disease and relapsing fever. These organisms are commonly transmitted to humans by arthropod vectors including ticks, mite, and lice. Here, we report the molecular detection of a Borrelia sp. from a Haemaphysalis hystricis Supino tick collected from wildlife in an Orang Asli settlement in Selangor, Malaysia. Phylogenetic analyses of partial 16s rRNA and flaB gene sequences revealed that the Borrelia sp. is closely related to the relapsing fever group borreliae, Borrelia lonestari, Borrelia miyamotoi, and Borrelia theileri, as well as a number of uncharacterized Borrelia sp. from ticks in Portugal and Japan. To our knowledge, this is the first report of a Borrelia sp. detected in H. hystricis, and in Malaysia. The zoonotic potential of this Borrelia sp. merits further investigation.
Publisher: Malaysian Society of Parasitology and Tropical Medicine
Date: 30-12-2020
DOI: 10.47665/TB.37.4.884
Publisher: Elsevier BV
Date: 06-2021
Publisher: Elsevier BV
Date: 10-2011
Publisher: Mary Ann Liebert Inc
Date: 2011
Abstract: The Toll-like receptors (TLRs) are innate sensors that recognize both microbial and endogenous ligands, initiating the host defense response. TLRs initiate the potent proinflammatory response to infection, are the target for adjuvants, and are essential for the establishment and maturation of adaptive immunity. As such they have been the interest of widespread research and the target of therapeutic intervention on multiple diseases. It has become apparent that expression of a subset of TLRs (TLR1, TLR2, TLR3, TLR5, and TLR7) is induced by Type I interferons (IFN). The role and impact of IFN expression on TLR responses is therefore critical in understanding the role of TLRs in disease, particularly as IFN itself is a downstream gene induced by specific TLRs. In this review we discuss the function and role of IFN-regulated TLRs in disease and how the role of IFN may impact upon TLR induction of the immune response in diseases, particularly in mouse models.
Publisher: Public Library of Science (PLoS)
Date: 06-11-2017
Publisher: MDPI AG
Date: 24-06-2021
DOI: 10.3390/MICROORGANISMS9071370
Abstract: Rickettsia raoultii is one of the causative agents of tick-borne lymphadenopathy in humans. This bacterium was previously isolated and propagated in tick cell lines however, the growth characteristics have not been investigated. Here, we present the replication kinetics of R. raoultii in cell lines derived from different tick genera (BME/CTVM23, RSE/PILS35, and IDE8). Tick cell cultures were infected in duplicate with cryopreserved R. raoultii prepared from homologous cell lines. By 12–14 days post infection, 100% of the cells were infected, as visualized in Giemsa-stained cytocentrifuge smears. R. raoultii growth curves, determined by rickettsiae-specific gltA qPCR, exhibited lag, exponential, stationary and death phases. Exponential phases of 4–12 days and generation times of 0.9–2.6 days were observed. R. raoultii in BME/CTVM23 and RSE/PILS35 cultures showed, respectively, 39.5- and 37.1-fold increases compared to the inoculum. In contrast, multiplication of R. raoultii in the IDE8 cultures was 110.1-fold greater than the inoculum with a 7-day stationary phase. These findings suggest variation in the growth kinetics of R. raoultii in the different tick cell lines tested, amongst which IDE8 cells could tolerate the highest levels of R. raoultii replication. Further studies of R. raoultii are needed for a better understanding of its persistence within tick populations.
Publisher: Systematic and Applied Acarology Society
Date: 30-10-2018
Abstract: AcknowledgmentsThis study was supported in parts by the research grants from University of Malaya, under the Research University Grants (RU016-2015) and (RU005-2017), and the Malaysia One Health University Network (MyOHUN) Seed Fund Award (MY/NCO/ACT/P001/SEEDFUND) provided by the United States Agency for International Development (USAID).
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Jing Jing Khoo.