ORCID Profile
0000-0002-3990-8070
Current Organisation
University of Queensland
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
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)
Fisheries Sciences | Aquaculture | Veterinary Microbiology (excl. Virology) | Fish Pests and Diseases | Invertebrate Biology | Aquaculture | Animal Nutrition | Gene Expression | Neurobiology | Ecology And Evolution Not Elsewhere Classified | Molecular Evolution | Zoology | Immunology
ANZSRC Socio-Economic Objective (SEO)
Aquaculture | Fish | Aquaculture Fin Fish (excl. Tuna) | Living resources (incl. impacts of fishing on non-target species) | Other (incl. production enhancement) |
Related Links
Publications
Gender differences in hemocyte immune parameters of bivalves: The Sydney rock oyster Saccostrea glomerata and the pearl oyster Pinctada fucata
Publisher: Elsevier BV
Date: 07-2012
DOI: 10.1016/J.FSI.2012.04.007
Abstract: Many authors have highlighted a high inter-in idual variability in immune parameters of marine bivalves. A high number of studies have reported the impact of external factors on hemocytes immune parameters such as temperature, salinity, pollutants or pathogens. However, only a few of them considered the impact of intrinsic parameters such as sex. Therefore, the present study assessed the impact of gender on hemocytes functions on two marine bivalves. Our results led to the conclusion that the gender contributes to this inter-in idual variability. When studying the impact of an environmental variable, a pathogen or a pollutant, the sex of each animal should be determined and taken into account in the analysis and interpretation of immune parameters.
Leucocyte integrins, but neither caspases nor NLR inflammasome are associated with lipopolysaccharide recognition and response in barramundi (Lates calcarifer)
Publisher: Elsevier BV
Date: 08-2019
DOI: 10.1016/J.FSI.2019.05.015
Abstract: The inflammatory response of fish to LPS is subdued, attributed to absence of TLR4, a key pro-inflammatory receptor for LPS in mammals. Nevertheless, LPS is processed in fish in a T-independent manner and is a protective antigen in fish vaccines, yet pathways for processing LPS in fish remain to be elucidated. Here, we report that caspases and NOD-like receptor inflammasomes typically responsible for LPS recognition and processing in mammals lack critical domains or are absent in barramundi (Lates calcarifer). On the other hand, leucocyte integrins MAC-1 and LFA-1 were detected on the surface of neutrophil- and lymphocyte-like cells respectively in the barramundi spleen by immunocytochemistry, and leucocytes displaying MAC-1 or LFA-1 bound to Factor X and ESM-1 respectively. Exposure to MAC-1 and LFA-1 induced significant IL-1β expression post-stimulation with LPS compared to unstimulated and isotype controls, but the differences observed in TNF-α expression were inconclusive. Our findings implicate MAC-1 and LFA-1 involvement in immune processing of LPS in barramundi and in antigen processing in fish.
Streptococcus iniae: An aquatic pathogen of global veterinary significance and a challenging candidate for reliable vaccination
Publisher: Elsevier BV
Date: 16-05-2007
DOI: 10.1016/J.VETMIC.2007.03.002
Abstract: Streptococcus iniae has become one the most serious aquatic pathogens in the last decade causing high losses in farmed marine and freshwater finfish in warmer regions. Although first identified in 1976 from a captive Amazon freshwater dolphin, from which it derives its name, disease outbreaks had most likely been occurring for several decades in marine aquaculture in Japan. S. iniae is globally distributed throughout warm water finfish aquaculture. In common with other encapsulated beta-haemolytic streptococci and in direct contradiction to the phenomenal success story of bacterial vaccines in finfish aquaculture, control of S. iniae by vaccination has met with limited success. Thus, antibiotic usage is the current practice for reducing mortality and consequent economic loss. Vaccine failure appears to result in part from serotypic variation and, whilst 2 serotypes have been named, variation would appear to be more complex. S. iniae also has zoonotic potential, with human infections identified in the USA, Canada, and throughout Asia. In humans, infection is clearly opportunistic with all cases to date associated with direct infection of puncture wounds during preparation of contaminated fish, and generally in elderly or immunocompromised in iduals. Significant progress has been made in terms of research into pathogenic mechanisms of S. iniae, with recent research elucidating the role of capsule in virulence for fish through antiopsonic activity. In light of this recent coverage in the literature, the present review centres on areas of direct veterinary interest including identification, epidemiology, therapy and prevention in farmed finfish. Clearly as the prevalence of S. iniae and associated economic losses continue to increase, further work towards developing a reliable vaccine is essential. This would appear to require a much better understanding of cell-surface variability amongst S. iniae isolates.
From the basics to emerging diagnostic technologies: What is on the horizon for tilapia disease diagnostics?
Publisher: Wiley
Date: 02-2023
DOI: 10.1111/RAQ.12734
Abstract: Tilapia is an affordable protein source farmed in over 140 countries with the majority of production in low‐ and middle‐income countries. Intensification of tilapia farming has exacerbated losses caused by emerging and re‐emerging infectious diseases. Disease diagnostics play a crucial role in biosecurity and health management to mitigate disease loss and improve animal welfare in aquaculture. Three continuous levels of diagnostics (I, II and III) for aquatic species have been proposed by Food and Agriculture Organization of the United Nations (FAO) and the Network of Aquaculture Centers in Asia and the Pacific (NACA) to promote the integration of basic and advanced methods to achieve accurate and meaningful interpretation of diagnostic results. However, the recent proliferation of cutting‐edge molecular methods applied in the diagnosis of diseases of aquacultured animals has shifted the focus of researchers and users away from basic approaches and toward molecular diagnostics, despite the fact that many diseases can be rapidly diagnosed using inexpensive, simple microscopic examination and that most emerging diseases in aquaculture were discovered by histopathology. This review, therefore, revisits and highlights the importance of the three levels of diagnostics for diseases of tilapia, particularly the frequently overlooked basic procedures (e.g., case history records, gross pathology, presumptive diagnostic methods and histopathology). The review also covers current and emerging molecular diagnostic technologies for tilapia pathogens including polymerase chain reaction methods (conventional, quantitative, digital), isothermal lification methods Loop‐mediated Isothermal Amplification (LAMP), recombinase polymerase lification (RPA), clustered regularly interspaced short palindromic repeats (CRISPR)‐based detection, lateral flow immunoassays, as well as discussing what is on the horizon for tilapia disease diagnostics (next generation sequencing, artificial intelligence, environmental Deoxyribonucleic Acid (DNA) and Ribonucleic Acid (RNA) and point‐of‐care testing) providing a future vision for transferring these technologies to farmers and stakeholders for a sustainable aquatic food system transformation.
“Vaccination” of shrimp against viral pathogens: Phenomenology and underlying mechanisms
Publisher: Elsevier BV
Date: 09-2008
DOI: 10.1016/J.VACCINE.2008.07.019
Abstract: The global shrimp aquaculture industry is worth in excess of US $10 billion annually, but continues to be beset by endemic viral diseases. The ability to vaccinate shrimp and other crustaceans against specific viral diseases is therefore of global economic and biosecurity significance. Higher vertebrates, including humans, have an adaptive immunity that enables them to specifically "remember" exposure to pathogens and respond with increased efficiency on subsequent encounters, forming the basis of vaccination. It has been widely accepted that invertebrates do not have such a system. However, there is mounting evidence for specific immune memory in crustaceans, including shrimp. This review explores the phenomenon of antiviral immunity in shrimp and explores this paradigm shift in the context of potential vaccination strategies for shrimp aquaculture.
Regulation of bacterial communities through antimicrobial activity by the coral holobiont
Publisher: Springer Science and Business Media LLC
Date: 08-10-2012
DOI: 10.1007/S00248-011-9946-0
Abstract: Interactions between corals and associated bacteria and amongst these bacterial groups are likely to play a key role in coral health. However, the complexity of these interactions is poorly understood. We investigated the functional role of specific coral-associated bacteria in maintaining microbial communities on the coral Acropora millepora (Ehrenberg 1834) and the ability of coral mucus to support or inhibit bacterial growth. Culture-independent techniques were used to assess bacterial community structures whilst bacterial culture was employed to assess intra- and inter-specific antimicrobial activities of bacteria. Members of Pseudoalteromonas and ribotypes closely related to Vibrio coralliilyticus displayed potent antimicrobial activity against a range of other cultured isolates and grew readily on detached coral mucus. Although such bacterial ribotypes would be expected to have a competitive advantage, they were rare or absent on intact and healthy coral colonies growing in situ (analysed using denaturing gradient gel electrophoresis and 16S rRNA gene sequencing). The most abundant bacterial ribotypes found on healthy corals were Gammaproteobacteria, previously defined as type A coral associates. Our results indicate that this group of bacteria and specific members of the Alphaproteobacteria described here as 'type B associates' may be important functional groups for coral health. We suggest that bacterial communities on coral are kept in check by a combination of host-derived and microbial interactions and that the type A associates in particular may play a key role in maintaining stability of microbial communities on healthy coral colonies.
Parasites of QX-resistant and wild-type Sydney rock oysters (Saccostrea glomerata) in Moreton Bay, SE Queensland, Australia: Diversity and host response
Publisher: Elsevier BV
Date: 03-2013
DOI: 10.1016/J.JIP.2012.12.006
Abstract: Wild caught (WC) and QX resistant (QXR) Sydney rock oysters were introduced at North Stradbroke Island and Pimpama River, SE Queensland, Australia, and s led monthly during 1 year. Three groups of parasites/diseases were identified by observation of histological sections: (1) Marteilia sydneyi (Queensland unknown (QX) disease) and Steinhausia sp. (Microsporidia) characterized by a high prevalence and deleterious impact on the host (2) disseminated neoplasia and the trematode Proctoeces sp. characterized by low prevalence but deleterious effects on the host (3) parasites or symbionts with no detectable effect on the host: trematodes, ciliates, turbellarians and metacestodes. Mortality rates were similar between both oyster lines but higher at Pimpama River (reaching around 90%) than Stradbroke Island, mostly because of QX disease and, to a lesser extent, to the unfavourable environmental conditions of the summer 2010-2011. Lower prevalences of QX disease at Stradbroke Island probably related to the relative lack of intermediate hosts of the parasite and to lower freshwater input. Surprisingly, no difference in prevalence of QX disease was observed between the two oyster lines.
Mixed culture purple phototrophic bacteria is an effective fishmeal replacement in aquaculture
Publisher: Elsevier BV
Date: 08-2019
Reduced salinity, but not estuarine acidification, is a cause of immune-suppression in the Sydney rock oyster Saccostrea glomerata
Publisher: Inter-Research Science Center
Date: 08-03-2010
DOI: 10.3354/MEPS08430
Kinetics of juvenile sea bass (Dicentrarchus labrax, L.) systemic and mucosal antibody secreting cell response to different antigens (Photobacterium damselae spp. piscicida, Vibrio anguillarum and DNP)
Publisher: Elsevier BV
Date: 05-2001
Abstract: The ELISPOT assay was used to measure the number of specific antibody secreting cells (ASC) induced during the primary and secondary immune responses in the spleen, head kidney and gut of juvenile (5 g) sea bass (Dicentrarchus labrax) to bacterial (Vibrio anguillarum and Photobacterium damselae ssp. piscicida) and hapten dinitrophenyl-conjugated to keyhole limpet haemocyanin (DNP-KLH) antigens administered intraperitoneally. High variability among in iduals was observed at each s ling day. All fish were bath vaccinated to V. anguillarum at an earlier stage (2 g) in the farm of origin prior to the development of the experiments, and therefore only secondary and tertiary responses were measured in the group immunised with this bacterium. Significant differences to the controls were observed in the primary responses of the head kidney and the spleen to P. damselae ssp. piscicida and DNP, respectively. Frequency analysis of the production of ASC suggests that significant responses in the gut might be masked by the high error variance. The peak of the primary response was observed 4 days earlier to DNP (18-20 days post-immunisation) and it was significantly higher than the response to P. damselae ssp. piscicida. Higher numbers of ASC were observed in the secondary responses of the head kidney and spleen, although they were not statistically significantly different from the primary levels, probably due to the high error variance as supported by the frequency analysis. Nevertheless, together with a faster response (peak at 7 days post-immunisation), the data suggest that memory formation had occurred. Additionally, the data suggest that some suppression of the secondary immune response in the gut might have occurred. The head kidney appears to produce the highest number of specific ASC of the organs tested. It appears that sea bass show a relatively fast but short duration antibody response.
Interactions of head-kidney leucocytes from giant grouper, Epinephelus lanceolatus, with pathogenic Streptococcus agalactiae strains from marine and terrestrial origins
Publisher: Elsevier BV
Date: 07-2019
DOI: 10.1016/J.FSI.2019.04.058
Abstract: Streptococcus agalactiae (Group B Streptococcus, GBS) is emerging as a genetically erse species infecting farmed and wild fish, including commercially and culturally important groupers. To better understand how S. agalactiae are pathogenic in fish, we investigated interactions between isolates from fish and terrestrial hosts and the cellular immune system of Queensland grouper Epinephelus lanceolatus using flow cytometry. Adherent head-kidney leucocytes (HKL) from Queensland grouper displayed two main cell populations with distinct forward and side scatter by flow cytometry. The population of smaller and less complex cells (P1) was composed of monocytes, lymphocytes and thrombocytes, while the population of primarily larger and more complex cells (P2) comprised predominantly of macrophages and neutrophils. The cells in P2 had higher phagocytic index and capacity when incubated with fluorescent latex beads. HKL were activated by phorbol myristate acetate (PMA) but were unresponsive to lipopolysaccharide (LPS) and peptidoglycan (PTG), suggesting the absence of specific receptors on the surface of these cells for these ligands or a requirement for intermediates. In in vitro phagocytosis assays, all fish isolates of GBS activated a respiratory burst in P2 indicated by significant production of intracellular reactive oxygen species (ROS). Similarly, dog and cat isolates of different serotype and sequence type also induced ROS production in grouper HKL. However, human, crocodile and bovine isolates of GBS did not elicit significant ROS in HKL although they coincided with the highest phagocytic index. This suggests that these strains are capable of quenching ROS production. Terrestrial isolates significantly increased mortality of Queensland grouper leucocytes in vitro, aligned with a more erse repertoire of cellular toxins in these strains. Opsonisation of a marine strain and terrestrial strain of GBS with antiserum raised against the marine strain resulted in an increase in ROS production by HKL in both cases although there was low antigenic cross reactivity between the two strains by flow cytometry, reflecting their erse serotypes (Ib vs III). However, pre-incubation of either strain with normal serum from grouper also increased ROS production of HKL suggesting other opsonins may be involved. Based on these results it appears that piscine and terrestrial GBS isolates have contrasting strategies when interacting with the cellular immune system of Queensland grouper the former seemingly evading phagocytosis, whilst the latter are readily phagocytosed but counteract ROS production.
AQUACULTURE ANTIBACTERIALS ARE ANTAGONIZED BY SEAWATER CATIONS
Publisher: Wiley
Date: 09-1995
Resistance to serum killing may contribute to differences in the abilities of capsulate and non-capsulated isolates of lactococcus garvieae to cause disease in rainbow trout (Oncorhynchus mykiss L.).
Publisher: Elsevier BV
Date: 02-2002
Abstract: Three capsulated and two non-capsulated isolates of Lactococcus garvieae were investigated in terms of their wall proteins, virulence and interactions with rainbow trout immunoglobulin (Ig). All isolates were similar in integral membrane protein profile, and all were able to bind non-immune rainbow trout Ig, although different proteins appeared to be involved in Ig binding. However, whilst capsulated isolates were highly virulent, non-capsulated isolates were avirulent. This appeared to correlate with susceptibility of the non-capsulated isolates to rainbow trout normal serum. In contrast, the capsulated isolates were resistant to both normal and immune serum killing. In spite of this, passive immunisation of rainbow trout with specific anti-serum to L. garvieae was able to protect against challenge by capsulated isolates of L. garvieae. This suggests the antibody may have some other role in protection against disease caused by this important Gram-positive bacterial fish pathogen.
Effect of a hemiuroid trematode on the hemocyte immune parameters of the cockle Anadara trapezia
Publisher: Elsevier BV
Date: 09-2013
DOI: 10.1016/J.FSI.2013.07.010
Abstract: When a trematode parasite penetrates a potential molluscan host, it has to circumvent the host's internal defense system. In molluscs, the primary effector cells of this system are the hemocytes which orchestrate many of the cellular and humoral immune functions. Survival of the parasite can occur only in the absence of a successful immune response, and continued development only if the host is physiologically suitable. This study investigated hemocytic response against asexual stages of a hemiuroid trematode by its host, the marine bivalve Anadara trapezia. Hemocyte characteristic (type, morphology) and function (mortality, phagocytosis and oxidative activity) were analyzed by flow cytometry in parasitized and non-parasitized cockles. A. trapezia possesses two types of hemocytes: amebocytes and erythrocytes. Analysis of histological section showed that there was no host hemocytic response around hemiuroid sporocysts. The infection induced a significant increase of the total circulating hemocytes with a higher proportion of erythrocytes relative to amebocytes, coupled with a lower phagocytosis rate and a statistically non-significant decrease of the intracellular oxidative activity. No significant differences were observed in hemocyte size and complexity, mortality, or phagocytic capacity. Our results indicate that in A. trapezia, hemiuroids modulate the immune response by increasing the number of circulating hemocytes and decreasing phagocytosis.
Tank color increases growth, and alters color preference and spectral sensitivity, in barramundi (Lates calcarifer)
Publisher: Elsevier BV
Date: 12-2011
A high quality reference genome for the fish pathogen Streptococcus iniae
Publisher: Cold Spring Harbor Laboratory
Date: 19-12-2019
DOI: 10.1101/2019.12.17.880476
Abstract: Fish mortality caused by Streptococcus iniae is a major economic problem in fish aquaculture in warm and temperate regions globally. There is also risk of zoonotic infection by S. iniae through handling of contaminated fish. In this study, we present the complete genome sequence of S. iniae strain QMA0248, isolated from farmed barramundi in South Australia. The 2.12 Mb genome of S. iniae QMA0248 carries a 32 Kb prophage, a 12 Kb genomic island, and 92 discrete insertion sequence (IS) elements. These include 9 novel IS types that belong mostly to the IS 3 family. Comparative and phylogenetic analysis between S. iniae QMA0248 and publicly available complete S. iniae genomes revealed discrepancies that are likely due to misassembly in the genomes of isolates ISET0901 and ISNO. We also determined by long-range PCR that a tandem duplication of an rRNA region in the PacBio assembly of QMA0248 was an assembly error. A similar rRNA duplication in the PacBio genome of S. iniae 89353 may also be a misassembly. Our study not only highlights assembly problems in existing genomes, but provides a high quality reference genome for S. iniae QMA0248, including manually curated mobile genetic elements, that will assist future S. iniae comparative genomic and evolutionary studies.
Immersion challenge of naïve Atlantic salmon with cultured Nolandella sp. and Pseudoparamoeba sp. did not increase the severity of Neoparamoeba perurans‐induced amoebic gill disea
Publisher: Wiley
Date: 12-12-2020
DOI: 10.1111/JFD.13319
Isolation and characterization of koi herpesvirus (KHV) from Indonesia: identification of a new genetic lineage
Publisher: Wiley
Date: 16-12-2011
DOI: 10.1111/J.1365-2761.2010.01216.X
Abstract: Koi herpesvirus (KHV) is the aetiological agent of an emerging disease (KHVD) associated with mass mortalities in koi and common carp and reported from at least 30 countries. We report the first isolation of KHV from koi and common carp in Indonesia and initial characterization of the isolates. Clinical signs, histopathology and virion morphology are similar to those of isolates from other countries. Phylogenetic analyses using the thymidine kinase gene lified from each isolate and from carp tissue s les collected from KHVD outbreaks throughout Indonesia indicated that the Indonesian isolates are more closely related to the Asian than the European KHV lineage. Sequence analysis of two other variable regions between ORF29 and ORF31 (marker I) and near the start of ORF 133 (marker II) indicated that all Indonesian isolates displayed a marker I allele (I(++)) previously identified only in isolates of the Asian lineage. However, in the marker II region, all Indonesian isolates displayed the II(-) allele, which has been reported previously only amongst isolates of the European lineage, and nine of these displayed a mixed genotype (II(+)II(-)). The I(++)II(-) genotype has not been reported previously and appears to represent a new intermediate lineage that may have emerged in Indonesia.
Serum IgM heavy chain sub-isotypes and light chain variants revealed in giant grouper (Epinephelus lanceolatus) via protein A affinity purification, mass spectrometry and genome sequencing.
Publisher: Elsevier BV
Date: 06-2021
Genetic analysis of B lack T iger shrimp (P enaeus monodon) across its natural distribution range reveals more recent colonization of F iji and other
Publisher:
Wiley
Date:
22-07-2012
DOI:
10.1002/ECE3.316
Publisher: Wiley
Date: 22-07-2012
DOI: 10.1002/ECE3.316
FLUOROQUINOLONES DISPLAY RAPID BACTERICIDAL ACTIVITY AND LOW MUTATION FREQUENCIES AGAINST AEROMONAS-SALMONICIDA
Publisher: Wiley
Date: 11-1991
Multilocus Variable-Number Tandem-Repeat Analysis of Yersinia ruckeri Confirms the Existence of Host Specificity, Geographic Endemism, and Anthropogenic Dissemination of Virulent Clones
Publisher: American Society for Microbiology
Date: 15-08-2018
DOI: 10.1128/AEM.00730-18
Abstract: This comprehensive population study substantially improves our understanding of the epizootiological history and nature of an internationally important fish-pathogenic bacterium. The MLVA assay developed and presented represents a high-resolution typing tool particularly well suited for Yersinia ruckeri infection tracing, selection of strains for vaccine inclusion, and risk assessment. The ability of the assay to separate isolates into geographically linked and/or possibly host-specific clusters reflects its potential utility for maintenance of national biosecurity. The MLVA is internationally applicable and robust, and it provides clear, unambiguous, and easily interpreted results. Typing is reasonably inexpensive, with a moderate technological requirement, and may be completed from a harvested colony within a single working day. As the resulting MLVA profiles are readily portable, any Y. ruckeri strain may rapidly be placed in a global epizootiological context.
Differing cell population structure reflects differing activity of Percoll-separated pronephros and peritoneal leucocytes from barramundi (Lates calcarifer)
Publisher: Elsevier BV
Date: 07-2009
A reliable method for enrichment of neutrophils from peripheral blood in barramundi ( Lates calcarifer )
Publisher: Elsevier BV
Date: 11-2016
DOI: 10.1016/J.FSI.2016.09.028
Abstract: Neutrophils are a short-lived, terminally differentiated, innate immune cell, that are critical first responders during infection. Research into neutrophil-pathogen interactions in fish has primarily employed cells derived from the pro-nephros and nephros. Since these sites are also the location of neutrophil and other immune cell development, there may be some ambiguity in maturation and functional ability of these cells, and difficulty in differentiating the effects of neutrophils from those of macrophages and monocytes. In contrast, peripheral blood circulating neutrophils are mature and ready to respond, thus it may be more physiologically relevant to use these cells for immune studies when evaluating interactions with blood-borne pathogens. The enrichment of tropical, euryhaline fish blood cells cannot follow classic mammalian enrichment methods for several reasons: Fish have nucleated red blood cells (RBC's), a high number of reticulocytes, a very low number of granulocytic leukocytes and an osmotic tolerance, rendering techniques such as water lysis ineffective. Enrichment of neutrophils, while minimizing RBC contamination, is imperative for studies where luminescence or fluorescence signals may be confounded by background from an overabundance of RBC's. We have optimized a method for enriching neutrophils from peripheral blood, with an initial settlement step employing 6% dextran (Mr 450,000-650,000), for 30-60 min at room temperature, followed by density separation on an 8-step Percoll density gradient. This method provides a cell suspension comprising 20-50% neutrophils, free of contamination from reticulocytes. These are then suitable for luminometric or fluorometric downstream analyses.
Isolation of a novel strain of Bacillus pumilus from penaeid shrimp that is inhibitory against marine pathogens.
Publisher: Wiley
Date: 12-11-2009
DOI: 10.1111/J.1365-2761.2009.01084.X
Abstract: A bacterium was isolated from the mid-gut of healthy black tiger shrimp, Penaeus monodon, based on a large zone of inhibition in mixed culture on solid medium. The isolate was a Gram-positive, motile spore former, with an optimum pH range for growth in tryptone soya broth containing 2% NaCl of between pH 6 and 9. The bacterium was highly salt tolerant with concentrations between 0% and 8% having no detrimental effect on growth. The isolate was identified as Bacillus pumilus based on physiological capabilities using the API50CHB and Biolog systems. Amplification and sequencing of the 16S rRNA gene followed by phylogenetic analysis confirmed its identity. The Bacillus pumilus isolate was strongly inhibitory against the marine bacterial pathogens Vibrio alginolyticus, V. mimicus and V. harveyi, and weakly inhibitory against V. parahaemolyticus in cross-streaking assays on solid medium. The organism was marginally self-inhibitory, and inhibited B. licheniformis and B. subtilis. The suitability of the B. pumilus isolate for use as a probiotic in farmed shrimp was further supported by the absence of any of the known B. cereus enterotoxin genes. Based on these in vitro results, in vivo safety and efficacy trials are underway to determine suitability of the novel strain as a commercial probiotic.
Peroxide-inducible catalase in Aeromonas salmonicida subsp. salmonicida protects against exogenous hydrogen peroxide and killing by activated rainbow trout, Oncorhynchus mykiss L., macrophages.
Publisher: Elsevier BV
Date: 03-1999
Abstract: Aeromonas salmonicida subsp. salmonicida expresses a single cytoplasmically located catalase which was found to be inducible by exposure to 20 microM hydrogen peroxide in mid-exponential phase resulting in a 4 fold increase in activity. Subsequent exposure to 2 mM peroxide in late-exponential/early-stationary phase resulted in further induction of catalase activity which increased to 20 fold higher levels than those found in uninduced cultures. Exponentially induced cultures were protected against subsequent exposure to 10 mM peroxide which was lethal to non-induced cultures. Bacteria subjected to induction in mid-exponential and early-stationary phase were resistant to 100 mM peroxide, although viability was greatly reduced. Growth of the bacterium under iron-restricted conditions had no effect on the peroxide induction of catalase. As current evidence indicates, the latter is an iron-co-factored heme catalase, this result suggests that catalase induction has a high priority in the metabolism of iron. Furthermore, exposure to peroxide also induces expression of periplasmic MnSOD. A. salmonicida MT423 was resistant to normal rainbow trout macrophages, but was susceptible to killing by activated macrophages. However, if catalase was induced by prior exposure to 20 microM peroxide during mid-exponential phase, A. salmonicida was resistant to killing by activated macrophages. The ability of A. salmonicida to upregulate periplasmic MnSOD and cytoplasmic catalase production under iron restricted conditions and low level peroxide (conditions expected to exist during the early stages of an infection) may be vital for its ability to withstand attack by phagocytic cells in vivo.
Complete, closed and curated genome sequences of Photobacterium damselae subsp. piscicida isolates from Australia indicate mobilome-driven localized evolution and novel pathogenicity determinants
Publisher: Microbiology Society
Date: 22-04-2021
Abstract: Despite the recent advances in sequencing technologies, the complete assembly of multi-chromosome genomes of the Vibrionaceae , often containing several plasmids, remains challenging. Using a combination of Oxford Nanopore MinION long reads and short Illumina reads, we fully sequenced, closed and curated the genomes of two strains of a primary aquatic pathogen Photobacterium damselae subsp. piscicida isolated in Australia. These are also the first genome sequences of P. damselae subsp. piscicida isolated in Oceania and, to our knowledge, in the Southern hemisphere. We also investigated the phylogenetic relationships between Australian and overseas isolates, revealing that Australian P. damselae subsp. piscicida are more closely related to the Asian and American strains rather than to the European ones. We investigated the mobilome and present new evidence showing that a host specialization process and progressive adaptive evolution to fish are ongoing in P. damselae subsp. piscicida , and are largely mediated by transposable elements, predominantly in chromosome 2, and by plasmids. Finally, we identified two novel potential virulence determinants in P. damselae subsp. piscicida – a chorismate mutase gene, which is ubiquitously retained and co-localized with the AIP56 apoptogenic toxin-encoding gene on the pPHDP10 plasmid, and transfer-messenger RNA gene ssrA located on the main chromosome, homologous to a critical-to-virulence determinant in Yersinia pseudotuberculosis . Our study describes, to our knowledge, the only fully closed and manually curated genomes of P. damselae subsp. piscicida available to date, offering new insights into this important fish pathogen and its evolution.
An ancient and variable mannose-binding lectin from the coral Acropora millepora binds both pathogens and symbionts
Publisher: Elsevier BV
Date: 2008
DOI: 10.1016/J.DCI.2008.05.010
Abstract: Corals form the framework of the world's coral reefs and are under threat from increases in disease and bleaching (symbiotic dysfunction), yet the mechanisms of pathogen and symbiont recognition remain largely unknown. Here we describe the isolation and characterisation of an ancient mannose-binding lectin in the coral Acropora millepora, which is likely to be involved in both processes. The lectin ('Millectin') was isolated by affinity chromatography and was shown to bind to bacterial pathogens as well as coral symbionts, dinoflagellates of the genus Symbiodinium. cDNA analysis of Millectin indicate extensive sequence variation in the binding region, reflecting its ability to recognise various mannose-like carbohydrate structures on non-self cells, including symbionts and pathogens. This is the first mannose-binding lectin to show extensive sequence variability as observed for pattern recognition proteins in other invertebrate immune systems and, given that invertebrates rely on non-adaptive immunity, is a potential keystone component of coral defence mechanisms.
Role of capsule in serotypic differences and complement fixation by Lactococcus garvieae.
Publisher: Elsevier BV
Date: 02-2004
Linear and branched beta(1-3) D-glucans activate but do not prime teleost macrophages in vitro and are inactivated by dilute acid: implications for dietary immunostimulation.
Publisher: Elsevier BV
Date: 03-2009
DOI: 10.1016/J.FSI.2009.01.009
Abstract: Beta(1-3) glucans are a erse range of carbohydrate polymers of differing lengths and structures that make up the cell walls of yeast, fungi, algae and some plants and activate innate immune responses in plants, invertebrates and higher animals. Consequently glucans are often used as dietary immunostimulants in commercial feeds for aquacultured fish species. The present study investigates the capability of purified glucans of differing structures and configurations, including curdlan, paramylon, laminarin and purified yeast beta glucan to activate innate immunity in vitro using barramundi pronephros macrophages as a model, and compares them to Zymosan, a complex mixture derived from yeast cell walls, and lipopolysaccharide from Gram negative bacteria. All of the glucans were able to stimulate respiratory burst in barramundi macrophages at concentrations of 100 microg/mL and 1000 microg/mL, with curdlan eliciting the highest respiratory burst response at 1000 microg/mL. LPS and Zymosan were the only immunostimulants tested that could prime barramundi macrophages by incubating with low concentrations (0.1 and 1 microg/mL) for 24 h before triggering respiratory burst with PMA, suggesting teleost macrophages may not prime through the glucan receptor. As glucans are used as dietary immunostimulants, the pH of the barramundi stomach was assayed for 6 h following feeding and indicated that pH was as low as 2 for up to 6 h. Treating the glucans with dilute HCl at pH 2 completely neutralised their macrophage-activating capability. These results are important as they indicate that glucans do not prime barramundi macrophages but will activate them at high concentrations. However, it is debatable whether glucans will have any effect on macrophages if administered in the diet due to the combination of high concentration required and probable hydrolysis of the polymer structures as they pass through the acid environment of the stomach.
Evaluation of growth performance in a diallel cross of three strains of giant freshwater prawn (Macrobrachium rosenbergii) in Vietnam
Publisher: Elsevier BV
Date: 02-2009
The purine nucleotides guanine, adenine and inosine are a dietary requirement for optimal growth of black tiger prawn, P. monodon
Publisher: Elsevier BV
Date: 09-2013
The gill is a major organ for antibody secreting cell production following direct immersion of sea bass (Dicentrarchus labrax, L.) in a Photobacterium damselae ssp piscicida bacterin: an ontogenetic study
Publisher: Elsevier BV
Date: 2001
Abstract: Extremely high numbers of antibody secreting cells (ASC) were observed in the gills of sea bass fry immunised at three different age/sizes (initial weight of 0.1, 2 and 5 g) by direct immersion in a Photobacterium damselae spp. piscicida bacterin. The relatively low ASC production in the head kidney and spleen suggests that the systemic compartment was only slightly stimulated upon immersion vaccination. There was no response of corresponding magnitude in the gut as the one observed in the gills. A clear age effect was observed in the ASC response of the different groups, especially visible in the gills. Significantly higher numbers of specific ASC were observed in the gills of the two oldest groups (initial weight of 2 and 5 g) compared with the youngest fish (initial weight of 0.1 g), but the oldest groups were not significantly different from each other. Additionally, a more rapid response was observed with the ageing of the fish, with peak responses in all the organs at day 18, 16 and 8 post-immunisation in the smallest to largest fish, respectively. There was no evidence that direct immersion exposure to P. damselae ssp. piscicida at the earliest stages used in the present study (0.1 g) was tolerogenic. In the context of present knowledge, this study strongly supports the importance of the route of immunisation to locally stimulate ASC and the importance that the gills might have in specific responses.
Molecular Investigation of Recurrent Streptococcus iniae Epizootics Affecting Coral Reef Fish on an Oceanic Island Suggests at Least Two Distinct Emergence Events
Publisher: Frontiers Media SA
Date: 04-11-2021
DOI: 10.3389/FMICB.2021.749734
Abstract: Streptococcus iniae is an emerging zoonotic pathogen of increasing concern for aquaculture and has caused several epizootics in reef fishes from the Caribbean, the Red Sea and the Indian Ocean. To study the population structure, introduction pathways and evolution of S. iniae over recurring epizootics on Reunion Island, we developed and validated a Multi Locus Sequence Typing (MLST) panel using genomic data obtained from 89 isolates s led during epizootics occurring over the past 40years in Australia, Asia, the United States, Israel and Reunion Island. We selected eight housekeeping loci, which resulted in the greatest variation across the main S. iniae phylogenetic clades highlighted by the whole genomic dataset. We then applied the developed MLST to investigate the origin of S . iniae responsible for four epizootics on Reunion Island, first in inland aquaculture and then on the reefs from 1996 to 2014. Results suggest at least two independent S . iniae emergence events occurred on the island. Molecular data support that the first epizootic resulted from an introduction, with inland freshwater aquaculture facilities acting as a stepping-stone. Such an event may have been facilitated by the ecological flexibility of S. iniae , able to survive in both fresh and marine waters and the ability of the pathogen to infect multiple host species. By contrast, the second epizootic was associated with a distinct ST of cosmopolitan distribution that may have emerged as a result of environment disturbance. This novel tool will be effective at investigating recurrent epizootics occurring within a given environment or country that is despite the fact that S. iniae appears to have low genetic ersity within its lineage.
Rapid genotyping of tilapia lake virus (TiLV) using Nanopore sequencing
Publisher: Wiley
Date: 08-06-2021
DOI: 10.1111/JFD.13467
Abstract: Infectious diseases represent one of the major challenges to sustainable aquaculture production. Rapid, accurate diagnosis and genotyping of emerging pathogens during early‐suspected disease cases is critical to facilitate timely response to deploy adequate control measures and prevent or reduce spread. Currently, most laboratories use PCR to lify partial pathogen genomic regions, occasionally combined with sequencing of PCR licon(s) using conventional Sanger sequencing services for confirmatory diagnosis. The main limitation of this approach is the lengthy turnaround time. Here, we report an innovative approach using a previously developed specific PCR assay for pathogen diagnosis combined with a new Oxford Nanopore Technologies (ONT)‐based licon sequencing method for pathogen genotyping. Using fish clinical s les, we applied this approach for the rapid confirmation of PCR licon sequences identity and genotyping of tilapia lake virus (TiLV), a disease‐causing virus affecting tilapia aquaculture globally. The consensus sequences obtained after polishing exhibit strikingly high identity to references derived by Illumina and Sanger methods (99.83%–100%). This study suggests that ONT‐based licon sequencing is a promising platform to deploy in regional aquatic animal health diagnostic laboratories in low‐ and medium‐income countries, for fast identification and genotyping of emerging infectious pathogens from field s les within a single day.
Epizootics of Streptococcus agalactiae infection in captive rays from Queensland, Australia
Publisher: Wiley
Date: 24-08-2018
DOI: 10.1111/JFD.12701
Abstract: The aim of this study was to describe two epizootics of high mortalities from infection with Streptococcus agalactiae, occurring in captive rays held in a marine display aquarium in south-east Queensland, Australia, in 2009 and 2010. Five different species of rays were affected, including mangrove whiprays (Himantura granulata), estuary rays (Dasyatis fluviorum), eastern shovelnose rays (Aptychotrema rostrata), white-spotted eagle rays (Aetobatus narinari) and blue-spotted mask rays (Neotrygon kuhlii). This report describes the history of both epizootics including collection, quarantine and husbandry of rays, the disease epizootics, clinico-pathological features of the disease, antimicrobial therapy, autogenous vaccine production, and laboratory studies including clinical and histopathology, bacteriology, PCR, molecular serotyping and sequencing of the bacterium S. agalactiae.
Streptococcus iniae: serological differences, presence of capsule and resistance to immune serum killing
Publisher: Inter-Research Science Center
Date: 2003
DOI: 10.3354/DAO053241
Abstract: The biochemical profiles, presence of capsule, outer membrane protein profiles and serological interactions of isolates of Streptococcus iniae obtained from different geographical and fish host origins were examined. The isolates had very similar biochemical profiles using API 20 Strep but varied as to whether they were arginine dihydrolase-negative, -positive or -intermediate (AD-ve, AD+ve, AD+/-ve, respectively). Representatives of each AD type were compared in subsequent experiments. All types possessed a polysaccharide capsule. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analysis of outer membrane proteins or whole cells revealed no difference in banding patterns between isolates. All isolates were resistant to trout normal and specific immune serum and grew well in the presence of added fresh normal serum. Serological analyses of the isolates revealed antigenic differences. Trout antiserum against the AD+ve isolate did not agglutinate the AD-ve or AD+/-ve isolates, while antisera against the latter 2 types showed low agglutinating activity with all 3 isolates. When whole live cells of AD-ve and AD+ve isolates were dot-blotted, antiserum to the AD+ve isolate did not stain the AD-ve isolate, but antiserum to the AD-ve isolate stained both AD types. However, if the cells were pre-treated with Proteinase K (to remove surface-exposed protein antigens), the AD+ve isolate was stained only by its homologous antiserum. These results suggest that while certain protein antigens of the different AD type strains are immunologically cross-reactive, the capsular antigens appear to be AD type-specific. Furthermore, the results suggest that the cross-reactive antigens on the AD-ve isolate are effectively hidden by the strain-specific capsule, while they are partially exposed on the AD+ve isolate.
Transforming the untransformable with knockout minicircles: High‐efficiency transformation and vector‐free allelic exchange knockout in the fish pathogen Photobacterium damselae
Publisher: Wiley
Date: 08-2023
DOI: 10.1002/MBO3.1374
Abstract: Gene inactivation studies are critical in pathogenic bacteria, where insights into species biology can guide the development of vaccines and treatments. Allelic exchange via homologous recombination is a generic method of targeted gene editing in bacteria. However, generally applicable protocols are lacking, and suboptimal approaches are often used for nonstandard but epidemiologically important species. Photobacterium damselae subsp. piscicida ( Pdp ) is a primary pathogen of fish in aquaculture and has been considered hard to transform since the mid‐1990s. Consequently, conjugative transfer of RK2/RP4 suicide vectors from Escherichia coli S17‐1/SM10 donor strains, a system prone to off‐target mutagenesis, was used to deliver the allelic exchange DNA in previous studies. Here we have achieved efficient electrotransformation in Pdp using a salt‐free highly concentrated sucrose solution, which performs as a hypertonic wash buffer, cryoprotectant, and electroporation buffer. High‐efficiency transformation has enabled vector‐free mutagenesis for which we have employed circular minimalistic constructs (knockout minicircles) containing only allelic exchange essentials that were generated by Gibson assembly. Preparation of competent cells using sucrose and electroporation/integration of minicircles had virtually no detectable off‐target promutagenic effect. In contrast, a downstream sacB selection apparently induced several large deletions via mobilization of transposable elements. Electroporation of minicircles into sucrose‐treated cells is a versatile broadly applicable approach that may facilitate allelic exchange in a wide range of microbial species. The method permitted inactivation of a primary virulence factor unique to Pdp , apoptogenic toxin AIP56, demonstrating the efficacy of minicircles for difficult KO targets located on the high copy number of small plasmids.
Towards control of Streptococcus iniae.
Publisher: Centers for Disease Control and Prevention (CDC)
Date: 12-2009
Resistance of Black-lip learl oyster, Pinctada margaritifera, to infection by Ostreid herpes virus 1μvar under experimental challenge may be mediated by humoral antiviral activity
Publisher: Elsevier BV
Date: 05-2015
DOI: 10.1016/J.FSI.2015.02.026
Abstract: Ostreid herpesvirus 1 (OsHV-1) has induced mass mortalities of the larvae and spat of Pacific oysters, Crassostrea gigas, in Europe and, more recently, in Oceania. The production of pearls from the Black-lip pearl oyster, Pinctada margaritifera, represents the second largest source of income to the economies of French Polynesia and many Pacific Island nations that could be severely compromised in the event of a disease outbreak. Coincidentally with the occurrence of OsHV-1 in the southern hemisphere, C. gigas imported from New Zealand and France into French Polynesia tested positive for OsHV-1. Although interspecies viral transmission has been demonstrated, the transmissibility of OsHV-1 to P. margaritifera is unknown. We investigated the susceptibility of juvenile P. margaritifera to OsHV-1 μvar that were injected with tissue homogenates sourced from either naturally infected or healthy C. gigas. The infection challenge lasted 14 days post-injection (dpi) with s ling at 0, 1, 2, 3, 5, 7 and 14 days. Mortality rate, viral prevalence, and cellular immune responses in experimental animals were determined. Tissues were screened by light microscopy and TEM. Pacific oysters were also challenged and used as a positive control to validate the efficiency of OsHV-1 μvar infection. Viral particles and features such as marginated chromatin and highly electron dense nuclei were observed in C. gigas but not in P. margaritifera. Mortality rates and hemocyte immune parameters, including phagocytosis and respiratory burst, were similar between challenged and control P. margaritifera. Herpesvirus-inhibiting activity was demonstrated in the acellular fraction of the hemolymph from P. margaritifera, suggesting that the humoral immunity is critical in the defence against herpesvirus in pearl oysters. Overall, these results suggest that under the conditions of the experimental challenge, P. margaritifera was not sensitive to OsHV-1 μvar and was not an effective host/carrier. The nature and spectrum of activity of the humoral antiviral activity is worthy of further investigation.
Dietary soybean protein concentrate-induced intestinal disorder in marine farmed Atlantic salmon, Salmo salar is associated with alterations in gut microbiota
Publisher: Elsevier BV
Date: 09-2013
DOI: 10.1016/J.VETMIC.2013.05.009
Abstract: The aquaculture industry has made substantial progress in reducing the fishmeal content of feeds for carnivorous species, driven by demand for improved sustainability and reduced cost. Soybean protein concentrate (SPC) is an attractive replacement for fishmeal, but intestinal disorders have been reported in Atlantic salmon (Salmo salar) fed these diets at high seawater temperatures, with preliminary evidence suggesting SPC induces these disorders by altering the intestinal microbiota. We compared the intestinal microbiota of marine-farmed S. salar fed experimental diets with varying levels of SPC in mid- and late-summer. Terminal restriction fragment length polymorphism (T-RFLP) and 16S rRNA clone library analysis revealed the microbiota adherent to the intestinal tract of salmon is complex at the population level, but simple and highly variable at the in idual level. Temporal changes were observed with the bacterial ersity increasing in the intestinal tract in late summer. A Verrucomicrobia was the most frequently observed ribotype in early summer, whilst an Aliivibrio was the most frequently observed ribotype in late summer. Feeding SPC to salmon increased the bacterial ersity of the intestinal tract and resulted in the presence of bacteria not normally associated with marine fish (Escherichia and Propionibacterium). These diet-induced changes to the intestinal-microbiome could be ameliorated by inclusion of a prebiotic (mannan-oligosaccharide or MOS) to the diet. None of the experimental diets induced inflammation of the intestine as assessed by histopathology and expression of inflammatory cytokines. Our results support the "dysbiosis" hypothesis that SPC adversely affects the intestinal microbiota of Atlantic salmon.
Antibiotic Use by Small‐Scale Farmers for Freshwater Aquaculture in the Upper Mekong Delta, Vietnam
Publisher: Wiley
Date: 09-2019
DOI: 10.1002/AAH.10084
Abstract: This study describes antibiotic use by small-scale freshwater aquaculture farmers in the upper Mekong Delta in southwestern Vietnam and the knowledge and practices surrounding the cause and prevention of aquaculture disease in that region. Forty five farmers were included in the study, of which 19 (42%) cultivated tilapia Oreochromis spp., 13 (29%) Striped Catfish Pangasianodon hypophthalmus and 13 (29%) giant river prawns Macrobrachium rosenbergii. Antibiotics were used by farmers of tilapia and Striped Catfish (84% and 69% of farmers, respectively), but not by any of the prawn farmers. Most farmers (72%) used antibiotics for around 3 d when treating diseases, depending on the farmers' economic means and whether the fish recovered, as judged by the farmer. If farmers perceived that the antibiotic treatment had failed, the most common response was to change to another type of antibiotic. Some farmers also used antibiotics in the absence of clinical symptoms as a preventive measure. In the absence of rapid, cost-effective diagnostics, the likelihood for the incorrect use of antibiotics is high, which has implications for antibiotic resistance. Moreover, the sequential use of different antibiotics following therapeutic failure is a risk factor for the emergence of resistance. All farmers that were surveyed were aware of the risks associated with antibiotic use. This may lead to successful intervention toward reduced antibiotic use in freshwater fish farming in Vietnam.
The Evolution of a Specialized, Highly Virulent Fish Pathogen through Gene Loss and Acquisition of Host-Specific Survival Mechanisms
Publisher: American Society for Microbiology
Date: 26-07-2022
DOI: 10.1128/AEM.00222-22
Abstract: Photobacterium damselae subsp. damselae is a ubiquitous marine bacterium and opportunistic pathogen of compromised hosts of erse taxa. In contrast, its sister subspecies P. damselae subsp. piscicida ( Pdp ) is highly virulent in fish. Pdp has evolved from a single subclade of Pdd through gene loss and acquisition.
Longitudinal field survey during deployment of an emergency autogenous vaccine against Betanodavirus in farmed giant grouper (Epinephelus lanceolatus): Multiple factors contribute to outbreaks and survival
Publisher: Elsevier BV
Date: 02-2022
Enteric Redmouth Disease (ERM) (Yersinia ruckeri)
Publisher: CABI
Date: 2011
Streptococcus iniae cpsG alters capsular carbohydrate composition and is a cause of serotype switching in vaccinated fish
Publisher: Elsevier BV
Date: 09-2016
DOI: 10.1016/J.VETMIC.2016.08.011
Abstract: Streptococcus iniae causes septicaemia and meningitis in marine and freshwater fish wherever they are farmed in warm-temperate and tropical regions. Although serotype specific, vaccination with bacterins (killed bacterial cultures) is largely successful and vaccine failure occurs only occasionally through emergence of new capsular serotypes. Previously we showed that mutations in vaccine escapes are restricted to a limited repertoire of genes within the 20-gene capsular polysaccharide (cps) operon. cpsG, a putative UDP-galactose 4-epimerase, has three sequence types based on the insertion or deletion of the three amino acids leucine, serine and lysine in the substrate binding site of the protein. To elucidate the role of cpsG in capsular polysaccharide (CPS) biosynthesis and capsular composition, we first prepared isogenic knockout and complemented mutants of cpsG by allelic exchange mutagenesis. Deletion of cpsG resulted in changes to colony morphology and cell buoyant density, and also significantly decreased galactose content relative to glucose in the capsular polysaccharide as determined by GC-MS, consistent with epimerase activity of CpsG. There was also a metabolic penalty of cpsG knockout revealed by slower growth in complex media, and reduced proliferation in whole fish blood. Moreover, whilst antibodies raised in fish against the wild type cross-reacted in whole cell and cps ELISA, they did not cross-opsonise the mutant in a peripheral blood neutrophil opsonisation assay, consistent with reported vaccine escape. We have shown here that mutation in cpsG results in altered CPS composition and this in turn results in poor cross-opsonisation that explains some of the historic vaccination failure on fish farms in Australia.
Characterisation of surface blebbing and membrane vesicles produced by Flavobacterium psychrophilum
Publisher: Inter-Research Science Center
Date: 2005
DOI: 10.3354/DAO064201
Abstract: The surface of Flavobacterium psychrophilum was examined by electron microscopy to determine if previous findings of haemagglutination positive (HA+) and haemagglutination negative (HA-) abilities could be correlated with expression of pili or of a capsular layer. A thin capsular layer was observed in both HA+ and HA- strains but typical pili were absent. However, long, tubular blebs that released membrane vesicles (MVs) into the supernatant were observed on up to 94% of cells within 1 s le. The surface blebbing was increased for 1 strain following growth on media with restricted iron availability. The MVs had an intact membrane bilayer and were released from blebbing cells of both strains. The protein profiles of MVs, while containing some banding similarity with the profile of outer membrane preparations (OMPs) and of lysed whole cells (WCs), showed several bands that reacted strongly with rabbit anti-whole-cell antisera. Two distinct bands of approximately 62 and 58 kDA were highly expressed in the MVs and not seen in the OMP. MVs contained proteolytic activity towards gelatine but not towards casein and elastin, which were only degraded by live cells. Low molecular weight lipopolysaccharides (LPS) or lipooligosaccharides (LOS) were associated with the MVs. Only the MVs of the HA+ strain possessed haemagglutinin activity. These findings suggest that the F. psychrophilum may, through surface blebbing, release antigenic MVs that contain some proteolytic activity and may aid the bacterium in releasing nutrients from its surrounding environment as well as playing a role in impeding the immune response of its host.
The conserved surface M-protein SiMA of Streptococcus iniae is not effective as a cross-protective vaccine against differing capsular serotypes in farmed fish
Publisher: Elsevier BV
Date: 02-2013
DOI: 10.1016/J.VETMIC.2012.08.018
Abstract: Streptococcus iniae causes invasive infections in fresh and saltwater fish and occasional zoonoses. Vaccination against S. iniae is complicated by serotypic variation determined by capsular polysaccharide. A potential target for serologically cross-protective vaccines is the M-like protein SiMA, an essential virulence factor in S. iniae that is highly conserved amongst virulent strains. The present study determined how SiMA is regulated and investigated potential as a cross-protective vaccine for fish. Electrophoretic mobility shift suggested that SiMA is regulated by the multigene regulator Mgx via a binding site in the -35 region of the simA promoter. Moreover, expression of simA and mgx was highly correlated, with the highest level of simA and mgx expression during exponential growth under iron limitation (20-fold increase in relative expression compared to growth in Todd-Hewitt broth). Based on these results, a vaccination and challenge experiment was conducted in barramundi (Lates calcarifer) to determine whether SiMA is protective against S. iniae infection and cross-protective against a different capsular serotype. The challenge resulted in 60% mortality in control fish. Formalin-killed bacterins prepared from the challenge strain resulted in 100% protection, whereas bacterins prepared from a serotypically heterologous strain resulted in significantly reduced protection, even when culture conditions were manipulated to optimise SiMA expression. Moreover, recombinant SiMA protein was not protective against the challenge strain in spite of eliciting specific antibody response in vaccinated fish. Specific antibody did not increase oxidative activity or phagocytosis by barramundi macrophages. Indeed incubating S. iniae with antisera significantly reduced phagocytosis. Lack of specific-antibody mediated opsonisation in spite of 100% protection against challenge with the homologous vaccine suggests that other immune parameters result in protection of challenged fish.
Evolutionary epidemiology ofStreptococcus iniae: linking mutation rate dynamics with adaptation to novel immunological landscapes
Publisher: Cold Spring Harbor Laboratory
Date: 25-06-2018
DOI: 10.1101/355412
Abstract: Pathogens continuously adapt to changing host environments where variation in their virulence and antigenicity is critical to their long-term evolutionary success. The emergence of novel variants is accelerated in microbial mutator strains (mutators) deficient in DNA repair genes, most often from mismatch repair and oxidised-guanine repair systems (MMR and OG respectively). Bacterial MMR/OG mutants are abundant in clinical s les and show increased adaptive potential in experimental infection models, yet the role of mutators in the epidemiology and evolution of infectious disease is not well understood. Here we investigated the role of mutation rate dynamics in the evolution of a broad host range pathogen, Streptococcus iniae , using a set of 80 strains isolated globally over 40 years. We have resolved phylogenetic relationships using non-recombinant core genome variants, measured in vivo mutation rates by fluctuation analysis, identified variation in major MMR/OG genes and their regulatory regions, and phenotyped the major traits determining virulence in streptococci. We found that both mutation rate and MMR/OG genotype are remarkably conserved within phylogenetic clades but significantly differ between major phylogenetic lineages. Further, variation in MMR/OG loci correlates with occurrence of atypical virulence-associated phenotypes, infection in atypical hosts (mammals), and atypical tissue of a vaccinated primary hosts (barramundi bone). These findings suggest that mutators are likely to facilitate adaptations preceding major ersification events, and may promote emergence of variation permitting colonisation of a novel host tissue, novel host taxa (host jumps), and immune-escape in the vaccinated host.
Streptococcus iniae expresses a cell surface non-immune trout immunoglobulin-binding factor when grown in normal trout serum
Publisher: Elsevier BV
Date: 11-2003
DOI: 10.1016/S1050-4648(03)00021-4
Abstract: Three capsulated isolates of S. iniae representing serotype I and II and being arginine dihydrolase positive, negative or variable (AD+ve, AD-ve, AD+-ve) were investigated for their ability to bind rainbow trout serum immunoglobulin by the Fc region. Using a coagglutination assay with bacteria grown in Todd-Hewitt broth (THB), no evidence of non-specific Fc-binding of trout immunoglobulin (Ig) was obtained. However, when grown in normal trout serum, all isolates produced similar protein patterns in SDS-PAGE, but they were markedly different from the patterns of the bacteria grown in THB. Some bands with MW 70 kDa and over 100 kDa were very intense in the profiles of the serum-grown isolates. In Western blots, these bands of all isolates were immunostained with the conjugated goat antiserum to trout Ig, after blocking with normal goat serum, demonstrating that the bacteria had bound the trout Ig during growth in the serum. When the isolates were grown overnight in trout antiserum against Lactococcus garvieae they coagglutinated with L. garvieae cells but S. iniae isolates grown in normal trout serum did not. These data indicate that S. iniae grown in serum express surface factors which can bind trout Ig by the Fc-region.
Leucocyte integrins but not caspases or NLR inflammasome are associated with lipopolysaccharide recognition and response in barramundi (Lates calcarifer)
Publisher: Cold Spring Harbor Laboratory
Date: 25-04-2018
DOI: 10.1101/307017
Abstract: The inflammatory response of fish to LPS is subdued, attributed to absence of TLR4, a key pro-inflammatory receptor for LPS in mammals. Nevertheless, LPS is processed in fish in a T-independent manner and is a protective antigen in fish vaccines, yet pathways for processing LPS in fish remain to be elucidated. Here, we report that caspases and NOD-like receptor inflammasomes typically responsible for LPS recognition and processing in mammals lack critical domains or are absent in barramundi ( Lates calcarifer ). However, leucocyte integrins MAC-1 and LFA-1 induce pro-inflammatory cytokine expression poststimulation with LPS. Moreover, MAC-1 and LFA-1 were detected on the surface of neutrophil- and lymphocyte-like cells respectively in the barramundi spleen by immunocytochemistry, and leucocytes displaying MAC-1 or LFA-1 bound to Factor X and ESM-1 respectively. Our results implicate MAC-1 and LFA-1 in immune processing of LPS in barramundi and potentially in antigen processing in fish.
A high-quality reference genome for the fish pathogen Streptococcus iniae
Publisher: Microbiology Society
Date: 03-2022
Abstract: Fish mortality caused by Streptococcus iniae is a major economic problem in aquaculture in warm and temperate regions globally. There is also risk of zoonotic infection by S. iniae through handling of contaminated fish. In this study, we present the complete genome sequence of S. iniae strain QMA0248, isolated from farmed barramundi in South Australia. The 2.12 Mb genome of S. iniae QMA0248 carries a 32 kb prophage, a 12 kb genomic island and 92 discrete insertion sequence (IS) elements. These include nine novel IS types that belong mostly to the IS 3 family. Comparative and phylogenetic analysis between S. iniae QMA0248 and publicly available complete S. iniae genomes revealed discrepancies that are probably due to misassembly in the genomes of isolates ISET0901 and ISNO. Long-range PCR confirmed five rRNA loci in the PacBio assembly of QMA0248, and, unlike S. iniae 89353, no tandemly repeated rRNA loci in the consensus genome. However, we found sequence read evidence that the tandem rRNA repeat existed within a subpopulation of the original QMA0248 culture. Subsequent nanopore sequencing revealed that the tandem rRNA repeat was the most prevalent genotype, suggesting that there is selective pressure to maintain fewer rRNA copies under uncertain laboratory conditions. Our study not only highlights assembly problems in existing genomes, but provides a high-quality reference genome for S. iniae QMA0248, including manually curated mobile genetic elements, that will assist future S. iniae comparative genomic and evolutionary studies.
Autogenous vaccination in aquaculture: A locally enabled solution towards reduction of the global antimicrobial resistance problem
Publisher: Wiley
Date: 17-11-2022
DOI: 10.1111/RAQ.12633
Abstract: Antimicrobial resistance is a global public health crisis with attention focussed on food supply as part of the ‘One Health’ integration of veterinary, environmental and public health. Aquaculture has been the fastest growing livestock sector in recent decades and is critical to nutritional security in many low‐ and middle‐income countries (LMIC). With ready access to antibiotics and limited availability of veterinary support, disease control with antibiotics is poorly informed, often unrecorded and high in many countries where aquaculture growth is fastest. Vaccination of fish in LMIC with locally produced autogenous vaccines against bacterial diseases may provide a locally driven, cost‐effective means of reducing antibiotic use, replicating the successes achieved during the growth of Norway's aquaculture industry. Autogenous vaccines, as part of an informed veterinary health programme, have several advantages in terms of intellectual property, efficacy and flexibility. We consider access to fish vaccines in ex le countries of high aquaculture importance, including Thailand, Vietnam and Indonesia. We contrast the success of antimicrobial reduction in Norwegian salmon aquaculture with the high antibiotic use in the Chilean industry where vaccines are available, finding that regulation, planning, husbandry and environmental problems may increase disease incidence and severity. We identify technical, bureaucratic and infrastructural transitions that could facilitate implementation of autogenous vaccination in LMIC aquaculture against challenging socio‐economic and environmental backgrounds. The benefits of autogenous vaccination to animal welfare, transboundary biosecurity, local farmer and industry economics, and to public health, favour implementation in aquaculture as a locally enabled solution to the global problem of antimicrobial resistance.
Estimates of strain additive and non-additive genetic effects for growth traits in a diallel cross of three strains of giant freshwater prawn (Macrobrachium rosenbergii) in Vietnam
Publisher: Elsevier BV
Date: 02-2010
Host-directed evolution of a novel lactate oxidase in Streptococcus iniae isolates from barramundi (Lates calcarifer).
Publisher: American Society for Microbiology
Date: 05-2009
DOI: 10.1128/AEM.02147-08
Abstract: In Streptococcus iniae , lactate metabolism is dependent upon two proteins, lactate permease that mediates uptake and lactate oxidase, a flavin mononucleotide-dependent enzyme that catalyzes oxidation of α-hydroxyacids. A novel variant of the lactate oxidase gene, lctO , in Australian isolates of S. iniae from diseased barramundi was found during a diagnostic screen using LOX-1 and LOX-2 primers, yielding licons of 920 bp instead of the expected 869 bp. Sequencing of the novel gene variant (type 2) revealed a 51-nucleotide insertion in lctO , resulting in a 17-amino-acid repeat in the gene product, and three-dimensional modeling indicated formation of an extra loop in the monomeric protein structure. The activities of the lactate oxidase enzyme variants expressed in Escherichia coli were examined, indicating that the higher-molecular-weight type 2 enzyme exhibited higher activity. Growth rates of S. iniae expressing the novel type 2 enzyme were not reduced at lactate concentrations of 0.3% and 0.5%, whereas a strain expressing the type 1 enzyme exhibited reduced growth rates at these lactate concentrations. During a retrospective screen of 105 isolates of S. iniae from Australia, the United States, Canada, Israel, Réunion Island, and Thailand, the type 2 variant arose only in isolates from a single marine farm with unusually high tidal flow in the Northern Territory, Australia. Elevated plasma lactate levels in the fish, resulting from the effort of swimming in tidal flows of up to 3 knots, may exert sufficient selective pressure to maintain the novel, high-molecular-weight enzyme variant.
Koi Herpesvirus Encodes and Expresses a Functional Interleukin-10
Publisher: American Society for Microbiology
Date: 11-2012
DOI: 10.1128/JVI.00957-12
Abstract: Koi herpesvirus (KHV) (species Cyprinid herpesvirus 3 ) ORF134 was shown to transcribe a spliced transcript encoding a 179-amino-acid (aa) interleukin-10 (IL-10) homolog (khvIL-10) in koi fin (KF-1) cells. Pairwise sequence alignment indicated that the expressed product shares 25% identity with carp IL-10, 22 to 24% identity with mammalian (including primate) IL-10s, and 19.1% identity with European eel herpesvirus IL-10 (ahvIL-10). In phylogenetic analyses, khvIL-10 fell in a ergent position from all host IL-10 sequences, indicating extensive structural ergence following capture from the host. In KHV-infected fish, khvIL-10 transcripts were observed to be highly expressed during the acute and reactivation phases but to be expressed at very low levels during low-temperature-induced persistence. Similarly, KHV early (helicase [Hel] and DNA polymerase [DNAP]) and late (intercapsomeric triplex protein [ITP] and major capsid protein [MCP]) genes were also expressed at high levels during the acute and reactivation phases, but only low-level expression of the ITP gene was detected during the persistent phase. Injection of khvIL-10 mRNA into zebrafish ( Danio rerio ) embryos increased the number of lysozyme-positive cells to a similar degree as zebrafish IL-10. Downregulation of the IL-10 receptor long chain (IL-10R1) using a specific morpholino abrogated the response to both khvIL-10 and zebrafish IL-10 transcripts, indicating that, despite the structural ergence, khvIL-10 functions via this receptor. This is the first report describing the characteristics of a functional viral IL-10 gene in the Alloherpesviridae .
Genetic variability amongst Streptococcus iniae isolates from Australia.
Publisher: Wiley
Date: 18-03-2008
Rapid genotyping of tilapia lake virus (TiLV) using Nanopore sequencing
Publisher: Cold Spring Harbor Laboratory
Date: 30-03-2021
DOI: 10.1101/2021.03.29.437503
Abstract: Infectious diseases represent one of the major challenges to sustainable aquaculture production. Rapid, accurate diagnosis and genotyping of emerging pathogens during early-suspected disease cases is critical to facilitate timely response to deploy adequate control measures and prevent or reduce spread. Currently, most laboratories use PCR to lify partial pathogen genomic regions, occasionally combined with sequencing of PCR licon(s) using conventional Sanger sequencing services for confirmatory diagnosis. The main limitation of this approach is the lengthy turnaround time. Here, we report an innovative approach using a previously developed specific PCR assay for pathogen diagnosis combined with a new Oxford Nanopore Technologies (ONT)-based licon sequencing method for pathogen genotyping. Using fish clinical s les, we applied this approach for the rapid confirmation of PCR licon sequences identity and genotyping of tilapia lake virus (TiLV), a disease-causing virus affecting tilapia aquaculture globally. The consensus sequences obtained after polishing exhibit strikingly high identity to references derived by Illumina and Sanger methods (99.83-100%). This study suggests that ONT-based licon sequencing is a promising platform to deploy in regional aquatic animal health diagnostic laboratories in low and medium income countries, for fast identification and genotyping of emerging infectious pathogens from field s les within a single day.
Identification of Barramundi (Lates calcarifer) DC-SCRIPT, a Specific Molecular Marker for Dendritic Cells in Fish
Publisher: Public Library of Science (PLoS)
Date: 14-07-2015
Whole genome analysis of Yersinia ruckeri isolated over 27 years in Australia and New Zealand reveals geographical endemism over multiple lineages and recent evolution under host selection.
Publisher: Microbiology Society
Date: 30-11-2016
Regulation of Bacterial Communities Through Antimicrobial Activity by the Coral Holobiont
Publisher: No publisher found
Date: 2011
Microevolution of Streptococcus agalactiae ST-261 from Australia Indicates Dissemination via Imported Tilapia and Ongoing Adaptation to Marine Hosts or Environment
Publisher: American Society for Microbiology
Date: 15-08-2018
DOI: 10.1128/AEM.00859-18
Abstract: Streptococcus agalactiae (GBS) is a significant pathogen of humans and animals. Some lineages have become adapted to particular hosts, and serotype Ib is highly specialized to fish. Here, we show that this lineage is likely to have been distributed widely by the global trade in tilapia for aquaculture, with probable introduction into Australia in the 1970s and subsequent dissemination in wild fish populations. We report here the variability in the polysaccharide capsule among this lineage but identify a cohort of common surface proteins that may be a focus of future vaccine development to reduce the biosecurity risk in international fish trade.
Vaccination for emergency and long-term control of Betanodavirus in Australian marine aquaculture
Publisher: The University of Queensland; Fisheries Research and Development Corporation
Date: 02-2023
DOI: 10.14264/1444C70
A diversity of amoebae colonise the gills of farmed Atlantic salmon (Salmo salar) with amoebic gill disease (AGD)
Publisher: Elsevier BV
Date: 02-2019
DOI: 10.1016/J.EJOP.2018.10.003
Abstract: Neoparamoeba perurans is the aetiological agent of amoebic gill disease (AGD) in salmonids, however multiple other amoeba species colonise the gills and their role in AGD is unknown. Taxonomic assessments of these accompanying amoebae on AGD-affected salmon have previously been based on gross morphology alone. The aim of the present study was to document the ersity of amoebae colonising the gills of AGD-affected farmed Atlantic salmon using a combination of morphological and sequence-based taxonomic methods. Amoebae were characterised morphologically via light microscopy and transmission electron microscopy, and by phylogenetic analyses based on the 18S rRNA gene and cytochrome oxidase subunit I (COI) gene. In addition to N. perurans, 11 other amoebozoans were isolated from the gills, and were classified within the genera Neoparamoeba, Paramoeba, Vexillifera, Pseudoparamoeba, Vannella and Nolandella. In some cases, such as Paramoeba eilhardi, this is the first time this species has been isolated from the gills of teleost fish. Furthermore, sequencing of both the 18S rRNA and COI gene revealed significant genetic variation within genera. We highlight that there is a far greater ersity of amoebae colonising AGD-affected gills than previously established.
Immune transcriptome reveals the mincle C-type lectin receptor acts as a partial replacement for TLR4 in lipopolysaccharide-mediated inflammatory response in barramundi (Lates calcarifer).
Publisher: Elsevier BV
Date: 03-2017
DOI: 10.1016/J.MOLIMM.2017.01.010
Abstract: Fish represent the most erse and abundant extant vertebrate infraclass. They are also one of the earliest ergent phyla with adaptive immunity based on antigen recognition by MHC and immunoglobulin. The aquaculture industry, which currently provides more than half of the fish for human consumption globally, has successfully exploited the adaptive immune system of fish through mass vaccination programs. However, vaccination against highly erse antigens, mostly carbohydrates, such as capsular polysaccharides and lipopolysaccharide (LPS) is challenging. Fish have a subdued innate response to LPS, but adaptive response is generally high and type-specific. To better understand the link between initial innate response and early onset of adaptive immunity to carbohydrate antigens in the perciform barramundi (Lates calcarifer), an immune transcriptome was prepared from pronephros and spleen following vaccination with LPS and peptidoglycan. From 163,661 transcripts derived by Illumina mRNA-Seq, most grouped in neuronal, endocrine or immune system categories, suggesting a close relationship between the three systems. Moreover, digestive enzyme transcripts in spleen appeared to be highly inducible in barramundi. Most of the known TLRs were transcribed in the barramundi spleen and HK transcriptome, with the notable exception of TLR4, which is primarily responsible for LPS recognition in mammals. Several C-type lectin receptors were also identified, including CD209, CD205, and CLEC4E (Mincle). As Mincle has been shown to bind LPS and is abundant on dendritic cells, its role in response to LPS in barramundi was further investigated. A high dose of LPS induced TNF-alpha expression via Mincle. However, IL-6 regulation, whilst still regulated in response to LPS, did not depend upon the Mincle pathway, suggesting other routes of activation. This study thus suggests that Mincle acts as a partial substitute for TLR4 in barramundi in the processing of LPS.
Dietary nucleotides are semi-essential nutrients for optimal growth of black tiger shrimp (Penaeus monodon)
Publisher: Elsevier BV
Date: 11-2012
Bacterial diversity of the digestive gland of Sydney rock oysters, Saccostrea glomerata infected with the paramyxean parasite, Marteilia sydneyi
Publisher: Oxford University Press (OUP)
Date: 23-01-2010
DOI: 10.1111/J.1365-2672.2010.04687.X
Abstract: To determine whether the infestation by the protozoan paramyxean parasite, Marteilia sydneyi, changes the bacterial community of the digestive gland of Sydney rock oysters, Saccostrea glomerata. Six 16S rDNA clone libraries were established from three M. sydneyi-infected and three un-infected oysters. Restriction enzyme analysis followed by sequencing representative clones revealed a total of 23 different operational taxonomic units (OTUs) in un-infected oysters, comprising the major phyla: Firmicutes, Proteobacteria, Cyanobacteria and Spirocheates, where the clone distribution was 44, 36, 7 and 5%, respectively. Close to half of the OTUs are not closely related to any other hitherto determined sequence. In contrast, S. glomerata infected by M. sydneyi had only one OTU present in the digestive gland. Phylogenetic analysis of the 16S rDNA sequence reveals that this dominant OTU, belonging to the alpha-Proteobacteria, is closely related to a Rickettsiales-like prokaryote (RLP). The microbiota of the digestive gland of Sydney rock oysters is changed by infection by M. sydneyi, becoming dominated by a RLP, and generally less erse. The bacterial community of un-infected S. glomerata differs from previous studies in that we identified the dominant taxa as Firmicutes and alpha-Proteobacteria, rather than heterotrophic gamma-Proteobacteria. This is the first culture-independent study of the microbiota of the digestive glands of edible oysters to the species level. The commercial viability of the Sydney rock oyster industry in Australia is currently threatened by Queensland Unknown disease and the changes in the bacterial community of S. glomerata corresponding with infection by M. sydneyi sheds further light on the link between parasite infection and mortality in this economically damaging disease.
Infection and pathology in Queensland grouper, Epinephelus lanceolatus, (Bloch), caused by exposure to Streptococcus agalactiae via different routes
Publisher: Wiley
Date: 13-08-2015
DOI: 10.1111/JFD.12273
Abstract: Since 2007, 96 wild Queensland groupers, Epinephelus lanceolatus, (Bloch), have been found dead in NE Australia. In some cases, Streptococcus agalactiae (Group B Streptococcus, GBS) was isolated. At present, a GBS isolate from a wild grouper case was employed in experimental challenge trials in hatchery-reared Queensland grouper by different routes of exposure. Injection resulted in rapid development of clinical signs including bilateral exophthalmia, hyperaemic skin or fins and abnormal swimming. Death occurred in, and GBS was re-isolated from, 98% fish injected and was detected by PCR in brain, head kidney and spleen from all fish, regardless of challenge dose. Challenge by immersion resulted in lower morbidity with a clear dose response. Whilst infection was established via oral challenge by admixture with feed, no mortality occurred. Histology showed pathology consistent with GBS infection in organs examined from all injected fish, from fish challenged with medium and high doses by immersion, and from high-dose oral challenge. These experimental challenges demonstrated that GBS isolated from wild Queensland grouper reproduced disease in experimentally challenged fish and resulted in pathology that was consistent with that seen in wild Queensland grouper infected with S. agalactiae.
In vitro susceptibility of the fish pathogen Aeromonas salmonicida to flumequine
Publisher: American Society for Microbiology
Date: 12-1991
Abstract: The activity of the fluoroquinolone flumequine was investigated against the fish pathogen Aeromonas salmonicida and was compared with that of oxolinic acid. Flumequine was more active than oxolinic acid in terms of its MIC against oxolinic acid-resistant isolates of A. salmonicida and was as active as oxolinic acid against susceptible isolates. In contrast to oxolinic acid, flumequine was bactericidal, with only 1% of the bacteria surviving 6 h of exposure to the drug at concentrations slightly above the MIC. Mutation to resistance to flumequine was found to occur at a lower frequency than that to oxolinic acid. Hence, in vitro, flumequine appears to possess some advantages over oxolinic acid against this fish pathogen.
Response and function of cutaneous mucosal and serum antibodies in barramundi (Lates calcarifer) acclimated in seawater and freshwater
Publisher: Elsevier BV
Date: 07-2006
DOI: 10.1016/J.FSI.2005.10.005
Abstract: Mucosal and serum antibody responses were studied in sibling barramundi (Lates calcarifer) acclimated in either seawater or freshwater following vaccination by intraperitoneal injection or direct immersion in an inactivated Streptococcus iniae vaccine. As expected, route of vaccination had a marked effect on immune response, with direct immersion resulting in low serum antibody levels against S. iniae by ELISA detected 21 days post vaccination at 26 degrees C, whilst a significant response was detected in mucus. A strong specific antibody response was detected in both mucus and serum 21 days following intraperitoneal injection. Fish acclimated in seawater prior to vaccination showed a markedly higher specific mucosal antibody response than sibling fish acclimated in freshwater, regardless of the route of vaccination, whilst the serum antibody response was not affected by salinity. Both mucosal and serum antibodies from fish in seawater and freshwater were capable of binding antigen at salinities similar to full strength seawater in a modified ELISA assay. These results indicate that this euryhaline fish species is not only able to mount significant specific antibody response in cutaneous mucus, but that these antibodies will function in the marine environment.
Polychaetes (Perinereis helleri) reared in sand beds filtering nutrients from shrimp (Penaeus monodon) culture ponds can transiently carry IHHNV
Publisher: Elsevier BV
Date: 11-2020
Microevolution of aquatic Streptococcus agalactiae ST-261 from Australia indicates dissemination via imported tilapia and ongoing adaptation to marine hosts or environment
Publisher: Cold Spring Harbor Laboratory
Date: 14-04-2018
DOI: 10.1101/301424
Abstract: Streptococcus agalactiae (GBS) causes disease in a wide range of animals. The serotype 1b lineage is highly adapted to aquatic hosts, exhibiting substantial genome reduction compared with terrestrial con-specifics. Here we sequence genomes from 40 GBS isolates including 25 from wild fish and captive stingrays in Australia, six local veterinary or human clinical isolates, and nine isolates from farmed tilapia in Honduras and compare with 42 genomes from public databases. Phylogenetic analysis based on non-recombinant core genome SNPs indicated that aquatic serotype Ib isolates from Queensland were distantly related to local veterinary and human clinical isolates. In contrast, Australian aquatic isolates are most closely related to a tilapia isolate from Israel, differing by only 63 core-genome SNPs. A consensus minimum spanning tree based on core genome SNPs indicates dissemination of ST-261 from an ancestral tilapia strain, which is congruent with several introductions of tilapia into Australia from Israel during the 1970s and 1980s. Pan-genome analysis identified 1,440 genes as core with the majority being dispensable or strain-specific with non-protein-coding intergenic regions (IGRs) ided amongst core and strain-specific genes. Aquatic serotype Ib strains have lost many virulence factors during adaptation, but six adhesins were well conserved across the aquatic isolates and might be critical for virulence in fish and targets for vaccine development. The close relationship amongst recent ST-261 isolates from Ghana, USA and China with the Israeli tilapia isolate from 1988 implicates the global trade in tilapia seed for aquaculture in the widespread dissemination of serotype Ib fish-adapted GBS. Streptococcus agalactiae (GBS) is a significant pathogen of humans and animals. Some lineages have become adapted to particular hosts and serotype Ib is highly specialized to fish. Here we show that this lineage is likely to have been distributed widely by the global trade in tilapia for aquaculture, with probable introduction into Australia in the 1970s and subsequent dissemination in wild fish populations. We report variability in the polysaccharide capsule amongst this lineage, but identify a cohort common surface proteins that may be a focus of future vaccine development to reduce the biosecurity risk in international fish trade.
Vaccination against streptococcal infections in farmed fish
Publisher: CSIRO Publishing
Date: 10-08-2016
DOI: 10.1071/MA16040
Evolutionary epidemiology of Streptococcus iniae: Linking mutation rate dynamics with adaptation to novel immunological landscapes
Publisher: Elsevier BV
Date: 11-2020
Immune parameters of QX-resistant and wild caught Saccostrea glomerata hemocytes in relation to Marteilia sydneyi infection
Publisher: Elsevier BV
Date: 12-2011
DOI: 10.1016/J.FSI.2011.09.003
Abstract: Sydney rock oysters (SRO) Saccostrea glomerata suffer mass mortalities during summer and autumn as a result of infection by a protozoan parasite Marteilia sydneyi (QX disease). Mass selected disease resistant (QXR) lines have been used with some success in affected estuaries in recent years, with resistance attributed to oxidative defense systems. However, the role of hemocytes in resistance to QX by SRO has not been fully explored. In the present study, fifty QXR and fifty wild caught (WC) oysters were collected from a lease at Pimpama River during a QX outbreak in January 2011. Hemocytes characteristics (type, morphology) and functions (mortality, phagocytosis and oxidative activity) from both oyster lines were analyzed by flow cytometry in the context of infection intensity and parasite viability (determined histologically). Amongst the QXR oysters, 20% were diseased containing viable parasite, 74% had killed M. sydneyi and 6% were uninfected. In contrast, 86% of WC oysters were diseased, 2% had killed M. sydneyi and 12% were healthy. Significant differences in hemocyte number and physiology between the two oyster lines were found (ANOVA). Phagocytosis rate and the mean oxidative activity per cell were similar between both oyster lines. Higher numbers of infiltrating and circulating hemocytes, higher percentage of circulating granulocytes, their higher size and complexity in QXR oysters, and the production of reactive oxygen species were associated with the ability to kill the parasite. High abundance of M. sydneyi in the digestive tubule epithelium of both oyster lines implied inability to kill the parasite at the beginning of the infection. However, QXR oysters had the ability to kill M. sydneyi at the stage of sporangiosorae in the epithelium of digestive tubules. The similar phagocytic ability of hemocytes from both oyster lines, the size of the parasite at this infection stage, and its localization suggested that encapsulation is likely to be the main process involved in the eradication of M. sydneyi by QXR oysters.
Two hepcidin-like antimicrobial peptides in Barramundi Lates calcarifer exhibit differing tissue tropism and are induced in response to lipopolysaccharide.
Publisher: Elsevier BV
Date: 08-2011
DOI: 10.1016/J.FSI.2011.05.027
Abstract: Genes encoding two hepcidin-like antimicrobial peptides were discovered in Barramundi, Lates calcarifer (barramundi, Giant sea perch). Analysis of the coding regions indicated that genes for each hepcidin comprised 3 exons and 2 introns. The deduced amino acid sequences for each molecule resulted in a protein comprising a signal sequence of 24 aa in each case, coupled to a prepropeptide of 75 aa for hepcidin 1 and 78 aa for hepcidin 2. A cleavage site was identified in each prepropetide at amino acid 64 with the cleavage motif--QKR/QS--resulting in mature peptides of 25 and 28 amino acids respectively. Each mature peptide contained 8 conserved cysteine residues and 3 dimensional modeling predicted a β-hairpin and β-sheet structure characteristic of human Liver Expressed Antimicrobial Peptide (LEAP). Analysis of the deduced amino acid sequences by BLAST with phylogenetic supported indicated that hepcidin 1 was a HAMP1-type peptide closely related to hepcidins identified in other Perciformes (Micropterus and Pseudosciaena), whilst hepcidin 2 was a HAMP2-type peptide most similar to a hepcidin previously identified in black rock fish (Sebastes schlegeli). Both hepcidin genes were inducible in barramundi following intraperitoneal injection with lipopolysaccharide, with elevated expression detected in liver and head kidney 3 h post IP injection for hepcidin 1 and in liver only for hepcidin 2. The elevated expression was transient with return to normal levels within 24-48 h. No significant expression of either peptide was detected in spleen, skin or gill following IP injection with LPS.
In vitro Activities Of 4-Quinolones Against The Fish Pathogen Aeromonas salmonicida
Publisher: American Society for Microbiology
Date: 09-1990
Abstract: The activities of five fluorinated 4-quinolones, namely, sarafloxacin, enrofloxacin, PD127391, PD117596, and CI934, against the fish pathogen Aeromonas salmonicida were investigated and compared with that of oxolinic acid.The results indicated that with the exception of CI934, these drugs are more active than oxolinic acid in terms of MIC. No inoculum effect was observed, but the drugs were less active at 10 degrees C than at 22 degrees C. The presence of 3% of NaCl caused an increase in drug activity. Resistance to the drugs appeared to be fairly stable, with only a small decrease in activity after 10 successive passages of the test strains on drug-free tryptone soya agar.
Aerosol dispersal of the fish pathogen, Amyloodinium ocellatum
Publisher: Elsevier BV
Date: 06-2006
A single-step, high throughput, and highly reproducible method for measuring IgM quantity and avidity directly from fish serum via biolayer interferometry (BLI)
Publisher: Elsevier BV
Date: 12-2021
DOI: 10.1016/J.FSI.2021.10.003
Abstract: Quantification of specific antibody responses is critical in determining activation of MHCII-dependent immune memory and is generally performed by enzyme-linked immunosorbent assay (ELISA). Antibody avidity for a particular antigen is also informative of the quality of the adaptive immune response following vaccination. Avidity can be determined by chaotropic elution ELISA, pre-absorption ELISA, or surface plasmon resonance (SPR), although multimeric antibodies such as IgM are problematic for SPR. ELISA-based assays are very time consuming, require secondary antibody reagents, and are poorly repeatable. Here we demonstrate that biolayer interferometry (BLI) using an Octet HTX instrument can robustly and reproducibly quantify and determine avidity of specific IgM for an antigen directly from fish serum in a single step. We collected sera from giant grouper (Epinephelus lanceolatus) that had been vaccinated with the hapten 2,4-dinitrophenol conjugated to keyhole limpet hemocyanin (DNP-KLH) and from control fish injected with phosphate buffered saline. The specific IgM in the serum and its avidity for DNP were quantified via ELISA and BLI. BLI was precise and highly repeatable for determination of the quantity and avidity of antibody in the serum compared to ELISA. The wet-lab preparation and machine running time for BLI was 3-5 times faster than ELISA to generate the same amount of data. The ELISA inter-plate variation significantly affected reproducibility while BLI was consistent and repeatable between s les and plates. Indeed, the consistency of BLI data indicated that technical triplicates were redundant. Biological replication alone was sufficient to elucidate the effect of treatments. However, BLI required a lower serum dilution than ELISA for similar sensitivity, and thus more serum was required to produce high resolution data. BLI is an extremely high-throughput assay, providing teleost serum IgM quantification and avidity data as a single-step, agile alternative to ELISA.
AMOXICILLIN RESISTANCE IN SCOTTISH ISOLATES OF AEROMONAS-SALMONICIDA
Publisher: Wiley
Date: 07-1994
Analysis of evolutionarily conserved innate immune components in coral links immunity and symbiosis
Publisher: Elsevier BV
Date: 11-2010
DOI: 10.1016/J.DCI.2010.06.016
Abstract: Reef-building corals are representatives of one of the earliest erging metazoan lineages and are experiencing increases in bleaching events (breakdown of the coral-Symbiodinium symbiosis) and disease outbreaks. The present study investigates the roles of two pattern recognition proteins, the mannose binding lectin Millectin and a complement factor C3-like protein (C3-Am), in the coral Acropora millepora. The results indicate that the innate immune functions of these molecules are conserved and arose early in evolution. C3-Am is expressed in response to injury, and may function as an opsonin. In contrast, Millectin expression is up-regulated in response to lipopolysaccharide and peptidoglycan. These observations, coupled with localization of Millectin in nematocysts in epidermal tissue, and reported binding of pathogens, are consistent with a key role for the lectin in innate immunity. Furthermore, Millectin was consistently detected binding to the symbiont Symbiodinium in vivo, indicating that the Millectin function of recognition and binding of non-self-entities may have been co-opted from an ancient innate immune system into a role in symbiosis.
Antibody increases phagocytosis and killing of Lactococcus garvieae by rainbow trout (Oncorhynchus mykiss, L.) macrophages
Publisher: Elsevier BV
Date: 02-2002
Abstract: The present study reports that specific antibody increased the bactericidal activity of rainbow trout head-kidney macrophages against virulent capsulated Lactococcus garvieae in the absence of complement. The observed increased bactericidal activity appeared to result from increased phagocytosis of capsulated L. garvieae in the presence of specific antibody and may in part explain the protective effect of antibody previously reported against this disease.
Prevalence of six amoeba species colonising the gills of farmed Atlantic salmon with amoebic gill disease (AGD) using qPCR
Publisher: Inter-Research Science Center
Date: 22-08-2019
DOI: 10.3354/AEI00325
Biodiversity of the intestinal microbiota of black tiger prawn, Penaeus monodon, increases with age and is only transiently impacted by major ingredient replacement in the diet
Publisher: Elsevier BV
Date: 02-2022
Wildlife as reservoirs for parasites infecting commercial species: host specificity and a redescription of Kudoa amamiensis from teleost fish in Australia
Publisher: Wiley
Date: 02-10-2008
DOI: 10.1111/J.1365-2761.2008.00958.X
Abstract: Parasites of the genus Kudoa (Phylum Myxozoa) have long been known to cause considerable losses to finfish aquaculture. One such parasite species, Kudoa amamiensis, causes unsightly white cysts in the skeletal muscle of yellowtail kingfish, Seriola quinqueradiata, in Japan rendering the fillets unmarketable. The authors who characterized K. amamiensis, Egusa & Nakajima, 1980, hypothesized that yellowtail kingfish, as non-natives to the area, were accidental hosts of the parasite and that it normally infects native reef fish (damselfish, Family Pomacentridae). Since then, we have found parasites that are consistent with the description of K. amamiensis in two species of damselfish and one species of carangid fish in Australia, and it has been recorded previously in another species of reef-associated fish. Our morphometric, histological and DNA results suggest that these specimens are K. amamiensis, and are new host records for that species. Furthermore, our observations show that reef fish may act as a reservoir of myxozoan infection for commercial species, and as such should be considered an infection pathway for species in aquaculture.
Serological and molecular typing of Tenacibaculum maritimum from New Zealand farmed salmon, Oncorhynchus tshawytscha
Publisher: Elsevier BV
Date: 2024
Iron acquisition mechanisms of Flavobacterium psychrophilum
Publisher: Wiley
Date: 07-2005
DOI: 10.1111/J.1365-2761.2005.00639.X
Abstract: Forty strains of Flavobacterium psychrophilum were tested for the production of siderophores using the universal Chrome Azurol S (CAS) assay. The majority of the strains (85%) were CAS positive (CAS+) and some (15%) were CAS negative (CAS-). The cryptic plasmid pCP1 was carried by all positive strains and was lacking from negative strains. While a weak catechol reaction was detectable in CAS+ culture supernatants, the CAS reaction was, to some extent, heat sensitive, questioning whether the positive reaction was caused only by siderophores. The ability to grow in vitro under iron-restricted conditions did not correlate with the CAS reactivity, as growth of both CAS+ and CAS- strains was similarly impaired under iron restriction induced by 2,2 dipyridyl. Suppressed growth under these conditions was restored by addition of FeCl3, haemoglobin and transferrin for both CAS+ and CAS- strains.
ALTERATIONS IN OUTER-MEMBRANE PROTEINS IDENTIFIED IN A CLINICAL ISOLATE OF AEROMONAS-SALMONICIDA SUBSP SALMONICIDA
Publisher: Wiley
Date: 05-1992
Parasites, pathological conditions and mortality in QX-resistant and wild-caught Sydney rock oysters, Saccostrea glomerata
Publisher: Elsevier BV
Date: 08-2008
Creating value from purple phototrophic bacteria via single-cell protein production
Publisher: Elsevier BV
Date: 08-2022
DOI: 10.1016/J.COPBIO.2022.102726
Abstract: Mixed culture purple phototrophic bacteria (PPB) is a rapidly emerging technology for resource recovery from wastewaters. PPB biomass can be used as single-cell protein, with a high protein content complemented by value-added components (e.g. pigments and polyhydroxyalkanoates), merging functionalities within a single product. This has the potential to increase the value and impact the economic feasibility, justifying higher capital costs for PPB photobioreactors for real-life applications. Artificial illumination is prohibitively expensive, and naturally illuminated, outdoor units are a critical next step. However, information required for informed technoeconomic assessment of single-cell protein from PPB is still missing and can only be determined in dedicated larger-scale, outdoor systems. Larger scale units are also required to supply feed for larger cohort trials. Although data from microalgae research can be used as starting point to estimate costs, they cannot be translated directly for PPB, as the organisms and metabolic growth are fundamentally different.
Bacterial Communities of Two Ubiquitous Great Barrier Reef Corals Reveals Both Site- and Species-Specificity of Common Bacterial Associates
Publisher: Public Library of Science (PLoS)
Date: 29-04-2010
Characteristics of cyprinid herpesvirus 3 in different phases of infection: Implications for disease transmission and control
Publisher: Elsevier BV
Date: 08-2014
DOI: 10.1016/J.VIRUSRES.2014.03.024
Abstract: Koi herpesvirus disease (KHVD) is an emerging and highly contagious viral disease of koi and common carp (Cyprinus carpio), causing mass mortalities and huge economic losses to the carp aquaculture industry. The disease has spread rapidly to 28 countries worldwide. However, mechanisms of koi herpesvirus (species Cyprinid herpesvirus 3 CyHV-3) transmission remain unclear. A potential experimental model of CyHV-3 infection in carp was used to characterise CyHV-3 in different phases of infection and to demonstrate that CyHV-3 persists in survivor fish and has the capacity to reactivate and transmit the disease to healthy fish. During acute infection, which occurred when fish were maintained at 22°C, viral genes were abundantly expressed and infectious virus was produced in association with tissue damage, clinical disease and mortality. In fish maintained at a lower temperature (11°C), viral DNA was present but viral gene expression was absent or greatly restricted, infectious virus was not recovered and there was no evidence of disease. Productive replication was re-initiated following an increase in water temperature to 22°C, resulting in 45% mortality. Shedding of reactivated virus killed 75% of cohabitating naïve fish, suggesting a potential risk for disease transmission.
Gibson Assembly facilitates bacterial allelic exchange mutagenesis
Publisher: Elsevier BV
Date: 2018
DOI: 10.1016/J.MIMET.2017.11.023
Abstract: Allelic exchange mutagenesis that relies on RecA-mediated homologous recombination up- and downstream from the targeted gene is a generalizable method of site-specific bacterial gene knock-out and knock-in. However, generation of a mutagenic DNA construct (alternative allele flanked by regions surrounding the gene target) and subsequent mutant selection are laborious procedures. Here we demonstrate allelic exchange knock-out facilitated by Gibson Assembly in Streptococcus iniae. Gibson Assembly allows rapid construction of a large allelic exchange cassette simultaneous with cloning, as well as rapid reconstruction of complete recombinant vector sequence when required. Additionally, we show that during two-step mutant selection, absence of recombination at one of the homologous regions (single cross-over) might be rapidly detected by colony PCR of meroploid clones and resolved by extension/shifting of corresponding sequence in DNA construct. The combination of Gibson Assembly for mutagenic DNA construction/redesign with colony PCR screening of meroploids to detect recombination at both sides of the exchange target may significantly accelerate generation of chromosomal mutants in a wide range of bacterial taxa.
Related Organisations
Moredun Research Institute
Location: United Kingdom of Great Britain and Northern Ireland
Marine Scotland Science
Location: United Kingdom of Great Britain and Northern Ireland
Heriot-Watt University
Location: United Kingdom of Great Britain and Northern Ireland
Aqua Health (Europe) Ltd
Location: United Kingdom of Great Britain and Northern Ireland
The University Of Edinburgh
Location: United Kingdom of Great Britain and Northern Ireland
Novartis Animal Health UK Limited
Location: United Kingdom of Great Britain and Northern Ireland
Related Funding Activities
A Pan-genome Reverse Vaccinology Approach To Disease Prevention In Farmed Fish
Start Date: 2013
End Date: 2016
Funder: Australian Research Council
View Funded ActivityFuture-proofing The Salmon Farming Industry Through Feeds For Thermal Tolerance
Start Date: 2020
End Date: 2023
Funder: Cooperative Research Centres, Australian Government Department of Industry
View Funded ActivityAquaculture Of The Tropical Abalone: Identifying And Selecting For Factors Promoting High Settlement, Survival And Growth
Start Date: 2005
End Date: 2008
Funder: Australian Research Council
View Funded ActivityEmerging Aquatic Diseases: A Novel Diagnostic Pipeline And Management Framework
Start Date: 2023
End Date: 2027
Funder: Ministry of Business, Innovation and Employment
View Funded ActivityFighting Disease On Farms: How Do Vaccinations Drive Evolution Of New Pathogen Strains?
Start Date: 2012
End Date: 2014
Funder: Australian Research Council
View Funded ActivityC-type Lectins And Innate Immunity In Barramundi
Start Date: 2005
End Date: 2008
Funder: Australian Research Council
View Funded ActivityAquatic Animal Health Subprogram: Investigation Of An Emerging Bacterial Disease In Wild Queensland Gropers, Marine Fish And Stingrays With Production Of Diagnostic Tools To Reduce The Spread Of Disease To Other States Of Australia
Start Date: 2010
End Date: 2011
Funder: Fisheries Research and Development Corporation
View Funded ActivityAlternate Diets For A Sustainable Aquaculture Industry: Neuroethology Of Feeding In Barramundi
Start Date: 2007
End Date: 2010
Funder: Australian Research Council
View Funded ActivityA Trivalent Vaccine For Sustainable Yellowtail Kingfish Growout
Start Date: 2018
End Date: 2021
Funder: Fisheries Research and Development Corporation
View Funded ActivityAquatic Animal Health Subprogram: Rapid Strain Identification Of The Bacterial Fish Pathogen Streptococcus Iniae And Development Of An Effective Polyvalent Vaccine For Australian Barramundi
Start Date: 2007
End Date: 2008
Funder: Fisheries Research and Development Corporation
View Funded ActivityVaccination For Emergency And Long-term Control Of Nodavirus In Australian Marine Aquaculture
Start Date: 2018
End Date: 2021
Funder: Fisheries Research and Development Corporation
View Funded ActivityLinkage Projects - Grant ID: LP0562409
Start Date: 12-2005
End Date: 06-2009
Amount: $115,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP120102755
Start Date: 2012
End Date: 12-2017
Amount: $270,000.00
Funder: Australian Research Council
View Funded ActivityLinkage Projects - Grant ID: LP0562602
Start Date: 08-2006
End Date: 12-2010
Amount: $121,444.00
Funder: Australian Research Council
View Funded ActivityLinkage Projects - Grant ID: LP130100242
Start Date: 07-2013
End Date: 01-2017
Amount: $196,452.00
Funder: Australian Research Council
View Funded ActivityLinkage Projects - Grant ID: LP0776985
Start Date: 06-2008
End Date: 03-2011
Amount: $125,880.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP0985995
Start Date: 2009
End Date: 03-2015
Amount: $870,000.00
Funder: Australian Research Council
View Funded Activity