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Ellen Ariel – 1st expert on this subject based on the ideXlab platform
Dose-dependent morbidity of freshwater turtle hatchlings, Emydura macquarii krefftii, inoculated with Ranavirus isolate (Bohle Iridovirus, Iridoviridae).Journal of General Virology, 2019Co-Authors: Wytamma Wirth, Lin Schwarzkopf, Lee F Skerratt, Anna Tzamouzaki, Ellen ArielAbstract:
Ranaviral infections cause mass die-offs in wild and captive turtle populations. Two experimental studies were performed to first determine the susceptibility of an Australian turtle species (Emydura macquarii krefftii) to different routes of infection and second examine the effect of viral titre on the morbidity in hatchlings. All inoculation routes (intracoelomic, intramuscular and oral) produced disease, but the clinical signs, histopathology and time to onset of disease varied with the route. The median infectious and lethal doses for intramuscularly inoculated hatchlings were 10(2.52) ((1.98-2.93)) and 10(4.43) ((3.81-5.19)) TCID50 ml(-1), respectively. Clinical signs began 14 to 29 days post-inoculation and the median survival time was 22 days (16-25) across all dose groups. For every 10-fold increase in dose, the odds of developing any clinical signs or severe clinical signs increased by 3.39 [P
dose dependent morbidity of freshwater turtle hatchlings emydura macquarii krefftii inoculated with ranavirus isolate Bohle Iridovirus iridoviridaeJournal of General Virology, 2019Co-Authors: Wytamma Wirth, Lin Schwarzkopf, Lee F Skerratt, Anna Tzamouzaki, Ellen ArielAbstract:
Ranaviral infections cause mass die-offs in wild and captive turtle populations. Two experimental studies were performed to first determine the susceptibility of an Australian turtle species (Emydura macquarii krefftii) to different routes of infection and second examine the effect of viral titre on the morbidity in hatchlings. All inoculation routes (intracoelomic, intramuscular and oral) produced disease, but the clinical signs, histopathology and time to onset of disease varied with the route. The median infectious and lethal doses for intramuscularly inoculated hatchlings were 10(2.52) ((1.98-2.93)) and 10(4.43) ((3.81-5.19)) TCID50 ml(-1), respectively. Clinical signs began 14 to 29 days post-inoculation and the median survival time was 22 days (16-25) across all dose groups. For every 10-fold increase in dose, the odds of developing any clinical signs or severe clinical signs increased by 3.39 [P<0.01, 95 % confidence interval (CI): 1.81-6.36] and 3.71 (P<0.01, 95 % CI: 1.76-7.80), respectively. Skin lesions, previously only reported in ranaviral infection in lizards, were observed in the majority of intramuscularly inoculated hatchlings that developed ranaviral disease. The histological changes were consistent with those in previous reports for reptiles and consisted of necrosis at or near the site of injection, in the spleen, liver and oral cavity. Systemic inflammation was also observed, predominantly affecting necrotic organs. The estimates reported here can be used to model ranaviral disease and quantify and manage at-risk populations.
pathogenesis of Bohle Iridovirus genus ranavirus in experimentally infected juvenile eastern water dragons intellagama lesueurii lesueuriiVeterinary Pathology, 2019Co-Authors: Alicia Maclaine, Maria J Forzan, Narges Mashkour, Jennifer L Scott, Ellen ArielAbstract:
Juvenile eastern water dragons (Intellagama lesueurii lesueurii) are highly susceptible to infection with Bohle Iridovirus (BIV), a species of ranavirus first isolated from ornate burrowing frogs i…
Alex D Hyatt – 2nd expert on this subject based on the ideXlab platform
Assessment of virally vectored autoimmunity as a biocontrol strategy for cane toadsPLOS ONE, 2011Co-Authors: Jackie A. Pallister, Nicole A Siddon, Damien C.t. Halliday, Anthony J. Robinson, Daryl Venables, Rhonda D. Voysey, Donna G. Boyle, Thayalini Shanmuganathan, Christopher M. Hardy, Alex D HyattAbstract:
The cane toad, Bufo (Chaunus) marinus, is one of the most notorious vertebrate pests introduced into Australia over the last 200 years and, so far, efforts to identify a naturally occurring B. marinus-specific pathogen for use as a biological control agent have been unsuccessful. We explored an alternative approach that entailed genetically modifying a pathogen with broad host specificity so that it no longer caused disease, but carried a gene to disrupt the cane toad life cycle in a species specific manner.
The adult beta globin gene was selected as the model gene for proof of concept of autoimmunity as a biocontrol method for cane toads. A previous report showed injection of bullfrog tadpoles with adult beta globin resulted in an alteration in the form of beta globin expressed in metamorphs as well as reduced survival. In B. marinus we established for the first time that the switch from tadpole to adult globin exists. The effect of injecting B. marinus tadpoles with purified recombinant adult globin protein was then assessed using behavioural (swim speed in tadpoles and jump length in metamorphs), developmental (time to metamorphosis, weight and length at various developmental stages, protein profile of adult globin) and genetic (adult globin mRNA levels) measures. However, we were unable to detect any differences between treated and control animals. Further, globin delivery using Bohle Iridovirus, an Australian ranavirus isolate belonging to the Iridovirus family, did not reduce the survival of metamorphs or alter the form of beta globin expressed in metamorphs.
While we were able to show for the first time that the switch from tadpole to adult globin does occur in B. marinus, we were not able to induce autoimmunity and disrupt metamorphosis. The short development time of B. marinus tadpoles may preclude this approach.
Bohle Iridovirus as a vector for heterologous gene expressionJournal of Virological Methods, 2007Co-Authors: Jackie Pallister, Sarah Goldie, Barbara E H Coupar, Brian J Shiell, Wojtek P Michalski, Nicole A Siddon, Alex D HyattAbstract:
Abstract The large double-stranded DNA (ds DNA) viruses were among the first to be used to construct recombinant viruses, but to date this has not been achieved with any members of the ds DNA virus family, Iridoviridae. We identified a non-essential gene, the viral homologue of eukaryotic initiation factor 2α (eIF-2α), in Bohle Iridovirus (BIV, genus Ranavirus). A recombinant BIV was constructed with the neomycin resistance gene and the Bufo marinus (cane toad) adult globin gene inserted into the BIV eIF-2α region. Adult globin expressed by the virus was detected on western blot, demonstrating that foreign genes can be expressed by the recombinant BIV in vitro and suggesting the possibility of using a recombinant BIV in the biological control of cane toads.
Development of real-time PCR assays for the detection and differentiation of Australian and European ranaviruses.Journal of Fish Diseases, 2007Co-Authors: Jackie Pallister, Alex D Hyatt, A Gould, D Harrison, James K. Jancovich, Hans G. HeineAbstract:
Serious systemic disease in fish and amphibians is associated with the ranaviruses, epizootic haernatopoietic necrosis virus (EHNV) and Bohle Iridovirus (BIV) in Australia, and European sheattish virus (ESV) and European catfish virus (ECV) in Europe. EHNV, ESV and ECV are recognized causative agents of the OlE (Office International des Epizooties) notifiable systemic necrotizing Iridovirus syndrome and are currently identified by proteinbased assays, none of which are able to rapidly identify the specific agents. The aim of this study was to develop T aqMan real-time PCR assays that differentiated these viruses using nucleotide sequence variation in two ranavirus genes. A conserved probe representing 100% sequence homology was used as a reference for virus-specific probes. The virus-specific probes produced a similar signal level to the conserved probe while those probes binding to non-target viral DNA produced an altered fluorescent curve. The pattern of probe binding was characteristic for each virus. Sensitivity, specificity and dynamic range of the assay were assessed. The test is currently useful as a research and initial screening tool, with the potential to become a sensitive and specific method for detection and differentiation of ranaviruses with further development.
Leigh Owens – 3rd expert on this subject based on the ideXlab platform
Serological survey of Australian native reptiles for exposure to ranavirusDiseases of Aquatic Organisms, 2017Co-Authors: Ellen Ariel, E. Elliott, Jonathan Meddings, J. Miller, M.b. Santos, Leigh OwensAbstract:
Ranaviruses have been isolated from many ectothermic vertebrates, and serological surveys of both amphibians and reptiles have shown the presence of ranaviral antibodies in a proportion of these populations. An enzyme-linked immunosorbent assay (ELISA) was developed to measure serum antibodies against ranavirus in Australian reptiles. The ELISA was validated with serum from challenge trials with Bohle Iridovirus (BIV) in 6 reptilian species. A preliminary serosurvey of northern Queensland riparian reptile fauna (saw-shelled turtles Myuchelys latisternum, Krefft’s river turtles Emydura macquarii krefftii, freshwater crocodiles Crocodylus johnstoni, as well as the snakes Boiga irregularis, Dendrelaphis punctulatus, Tropidonophis mairii, Morelia spilota, Liasis childreni and L. fuscus) revealed evidence of past exposure to Bohle iridoviral antigens in part of the population at several locations sampled. Furthermore, in Krefft’s river turtles and freshwater crocodiles, a statistically significant trend was apparent for larger reptiles to be more likely to have BIV-reactive sera than smaller individuals. The use of adult tortoise populations as sentinels can assist in monitoring the presence of BIV in northern Australian freshwater streams, and thereby the potential dangers to native fauna from this agent.
pathogenicity in six australian reptile species following experimental inoculation with Bohle IridovirusDiseases of Aquatic Organisms, 2015Co-Authors: Ellen Ariel, Jennifer L Scott, Wytamma Wirth, G W Burgess, Leigh OwensAbstract:
Ranaviruses are able to infect multiple species of fish, amphibian and reptile, and some strains are capable of interclass transmission. These numerous potential carriers and reservoir species compound efforts to control and contain infections in cultured and wild populations, and a comprehensive knowledge of susceptible species and life stage is necessary to inform such processes. Here we report on the challenge of 6 water-associated reptiles with Bohle Iridovirus (BIV) to investigate its potential pathogenicity in common native reptiles of the aquatic and riparian fauna of northern Queensland, Australia. Adult tortoises Elseya latisternum and Emydura krefftii, snakes Boiga irregularis, Dendrelaphis punctulatus and Amphiesma mairii, and yearling crocodiles Crocodylus johnstoni were exposed via intracoelomic inoculation or co-habitation with infected con-specifics, but none were adversely affected by the challenge conditions applied here. Bohle Iridovirus was found to be extremely virulent in hatchling tortoises E. latisternum and E. krefftii via intracoelomic challenge, as demonstrated by distinct lesions in multiple organs associated with specific immunohistochemistry staining and a lethal outcome (10/17) of the challenge. Virus was re-isolated from 2/5 E. latisternum, 4/12 E. krefftii and 1/3 brown tree snakes B. irregularis. Focal necrosis, haemorrhage and infiltration of granulocytes were frequently observed histologically in the pancreas, liver and sub-mucosa of the intestine of challenged tortoise hatchlings. Immunohistochemistry demonstrated the presence of ranavirus antigens in the necrotic lesions and in individual cells of the vascular endothelium, the connective tissue and in granulocytes associated with necrosis or present along serosal surfaces. The outcome of this study confirms hatchling tortoises are susceptible to BIV, thereby adding Australian reptiles to the host range of ranaviruses. Additionally, given that BIV was originally isolated from an amphibian, our study provides additional evidence that interclass transmission of ranavirus may occur in the wild.
influence of temperature and exposure time on the infectivity of Bohle Iridovirus a ranavirusAquaculture, 2012Co-Authors: K La Fauce, Ellen Ariel, Suzanne L Munns, Catherine M Rush, Leigh OwensAbstract:
Abstract This study examined the functional temperature range of a ranavirus outside host cells over increasing temperatures and exposure times and subsequently tested infectivity in cell culture. Initially, cell susceptibility was determined by incubating Bohle Iridovirus (BIV) at 30 °C, 40 °C, 50 °C and 60 °C for 5, 30 and 60 min and subsequently titrating samples in one epithelioma papulosum cyprinid (EPC) and two Bluegill fry 2 (BF2) lineages at 28 °C. Titres obtained in the three cell lines were similar and EPC cells were subsequently used to further investigate ranavirus infectivity with two degree increments in temperature between 40 °C and 60 °C for 5, 30 and 60 min. The rate of inactivation was found to be dependent on temperature and time of exposure. Bohle Iridovirus could replicate in EPC cells following exposure to most temperatures and prolonged time, but titers were reduced as temperature and time of exposure increased. Viral titres were greatest (10 8 TCID 50 /ml) after exposure to 30 °C and declined with increasing time of exposure and increasing temperature. Declines in BIV infectivity were largely between 40 °C (10 8 TCID 50 /ml) and 44 °C (10 5 TCID 50 /ml at 5 and 30 min and 10 3.5 TCID 50 /ml at 60 min) and secondly at temperatures greater than 52 °C (from 10 3.5 TCID 50 /ml and approaching zero with increasing temperature and time). Treatment at 58 °C for 60 min and 60 °C for 30 and 60 min resulted in complete loss of BIV infectivity. The results from this study show that ranavirus can withstand much higher temperatures than previously thought, which is fundamental for understanding ranavirus epidemiology, indirect transmission dynamics and for biosecurity purposes.