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Craig R. Brunetti - One of the best experts on this subject based on the ideXlab platform.
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Frog Virus 3 genomes reveal prevalent recombination between ranaVirus lineages and their origins in canada
Journal of Virology, 2019Co-Authors: Sibelle T Vilaca, Craig R. Brunetti, Joefelix Bienentreu, David Lesbarreres, Dennis L Murray, Christopher J KyleAbstract:RanaViruses are pathogens associated with the decline of amphibian populations across much of their distribution. In North America, Frog Virus 3 (FV3) is a widely distributed pathogen with wild populations of amphibians harboring different lineages and putative recombinants between FV3 and common midwife toad Virus (CMTV). These recombinants have higher pathogenicity, and CMTV-derived genes associated with virulence are reported in wild strains in Canada. However, while FV3 is linked to amphibian die-offs in North America, CMTVs have been reported only in commercial Frog farms in North America. We sequenced complete genomes of 18 FV3 isolates from three amphibian species to characterize genetic diversity of the lineages in Canada and infer possible recombinant regions. The 18 FV3 isolates displayed different signals of recombination, varying from none to interspersed recombination with previously isolated CMTV-like Viruses. In general, most recombination breakpoints were located within open reading frames (ORFs), generating new ORFs and proteins that were a mixture between FV3 and CMTV. A combined spatial and temporal phylogeny suggests the presence of the FV3 lineage in Canada is relatively contemporary (<100 years), corroborating the hypothesis that both CMTV- and FV3-like Viruses spread to North America when the international commercial amphibian trade started. Our results highlight the importance of pathogen surveillance and viral dynamics using full genomes to more clearly understand the mechanisms of disease origin and spread.IMPORTANCE Amphibian populations are declining worldwide, and these declines have been linked to a number of anthropogenic factors, including disease. Among the pathogens associated with amphibian mortality, ranaViruses have caused massive die-offs across continents. In North America, Frog Virus 3 (FV3) is a widespread ranaVirus that can infect wild and captive amphibians. In this study, we sequenced full FV3 genomes isolated from Frogs in Canada. We report widespread recombination between FV3 and common midwife toad Virus (CMTV). Phylogenies indicate a recent origin for FV3 in Canada, possibly as a result of international amphibian trade.
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Frog Virus 3 Genomes Reveal Prevalent Recombination between RanaVirus Lineages and Their Origins in Canada.
Journal of Virology, 2019Co-Authors: Sibelle T Vilaca, Craig R. Brunetti, Joefelix Bienentreu, David Lesbarreres, Dennis L Murray, Christopher J KyleAbstract:RanaViruses are pathogens associated with the decline of amphibian populations across much of their distribution. In North America, Frog Virus 3 (FV3) is a widely distributed pathogen with wild populations of amphibians harboring different lineages and putative recombinants between FV3 and common midwife toad Virus (CMTV). These recombinants have higher pathogenicity, and CMTV-derived genes associated with virulence are reported in wild strains in Canada. However, while FV3 is linked to amphibian die-offs in North America, CMTVs have been reported only in commercial Frog farms in North America. We sequenced complete genomes of 18 FV3 isolates from three amphibian species to characterize genetic diversity of the lineages in Canada and infer possible recombinant regions. The 18 FV3 isolates displayed different signals of recombination, varying from none to interspersed recombination with previously isolated CMTV-like Viruses. In general, most recombination breakpoints were located within open reading frames (ORFs), generating new ORFs and proteins that were a mixture between FV3 and CMTV. A combined spatial and temporal phylogeny suggests the presence of the FV3 lineage in Canada is relatively contemporary (
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Localization of Frog Virus 3 Conserved Viral Proteins 88R, 91R, and 94L
Viruses, 2019Co-Authors: Emily Penny, Craig R. BrunettiAbstract:The characterization of the function of conserved viral genes is central to developing a greater understanding of important aspects of viral replication or pathogenesis. A comparative genomic analysis of the iridoviral genomes identified 26 core genes conserved across the family Iridoviridae. Three of those conserved genes have no defined function; these include the homologs of Frog Virus 3 (FV3) open reading frames (ORFs) 88R, 91R, and 94L. Conserved viral genes that have been previously identified are known to participate in a number of viral activities including: transcriptional regulation, DNA replication/repair/modification/processing, protein modification, and viral structural proteins. To begin to characterize the conserved FV3 ORFs 88R, 91R, and 94L, we cloned the genes and determined their intracellular localization. We demonstrated that 88R localizes to the cytoplasm of the cell while 91R localizes to the nucleus and 94L localizes to the endoplasmic reticulum (ER).
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Effect of imidacloprid on the survival of Xenopus tadpoles challenged with wild type Frog Virus 3
Aquatic Toxicology, 2018Co-Authors: Morgan A. Hrynyk, Craig R. Brunetti, Leslie R. Kerr, Chris D. MetcalfeAbstract:Abstract The sensitivity of amphibians to RanaVirus may be increased by exposure to other environmental stressors, including chemical contaminants. Neonicotinoid insecticides comprise 27% of the global insecticide market and have been detected in wetlands and other aquatic habitats. The present study focused on the effects of exposure of pre-metamorphic Xenopus laevis to the neonicotinoid, imidacloprid (IMI) on sensitivity to Frog Virus 3 (FV3) infection. It was hypothesized that exposure of tadpoles to IMI at sublethal concentrations of 1 and 500 μg L−1 would increase FV3 related mortalities relative to tadpole mortalities in a control treatment with only the Virus. However, contrary to the predicted outcome, IMI reduced the rates of mortality following viral challenge, although the total mortalities by the 25th day after infection did not differ among the treatments. These results should not be interpreted as an indication that neonicotinoid insecticides are beneficial to aquatic ecosystems, since these insecticides cause toxic responses at low concentrations to other non-target aquatic organisms.
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cellular litaf interacts with Frog Virus 3 75l protein and alters its subcellular localization
Journal of Virology, 2013Co-Authors: Heather E. Eaton, Julie Metcalf, Andressa Ferreira Lacerda, Guillaume Desrochers, Annie Angers, Craig R. BrunettiAbstract:IridoViruses are a family of large double-stranded DNA (dsDNA) Viruses that are composed of 5 genera, including the LymphocystiVirus, RanaVirus, MegalocytiVirus, IridoVirus, and ChloriridoVirus genera. The Frog Virus 3 (FV3) 75L gene is a nonessential gene that is highly conserved throughout the members of the RanaVirus genus but is not found in other iridoViruses. FV3 75L shows high sequence similarity to a conserved domain found in the C terminus of LITAF, a small cellular protein with unknown function. Here we show that FV3 75L localizes to early endosomes, while LITAF localizes to late endosomes/lysosomes. Interestingly, when FV3 75L and LITAF are cotransfected into cells, LITAF can alter the subcellular localization of FV3 75L to late endosomes/lysosomes, where FV3 75L then colocalizes with LITAF. In addition, we demonstrated that virally produced 75L colocalizes with LITAF. We confirmed a physical interaction between LITAF and FV3 75L but found that this interaction was not mediated by two PPXY motifs in the N terminus of LITAF. Mutation of two PPXY motifs in LITAF did not affect the colocalization of LITAF and FV3 75L but did change the location of the two proteins from late endosomes/lysosomes to early endosomes.
Leon Grayfer - One of the best experts on this subject based on the ideXlab platform.
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class a scavenger receptors are used by Frog Virus 3 during its cellular entry
Viruses, 2019Co-Authors: Matthew Guerreiro, Leon Grayfer, Amulya Yaparla, Stephanie J DewitteorrAbstract:Frog Virus 3 (FV3) is the type species of the genus RanaVirus (family Iridoviridae). FV3 and FV3-like Viruses are globally distributed infectious agents with the capacity to replicate in three vertebrate classes (teleosts, amphibians, and reptiles). At the cellular level, FV3 and FV3-like Viruses can infect cells from virtually all vertebrate classes. To date, the cellular receptors that are involved in the FV3 entry process are unknown. Class A scavenger receptors (SR-As) are a family of evolutionarily conserved cell-surface receptors that bind a wide range of chemically distinct polyanionic ligands and can function as cellular receptors for other DNA Viruses, including vaccinia Virus and herpes simplex Virus. The present study aimed to determine whether SR-As are involved in FV3 cellular entry. By using well-defined SR-A competitive and non-competitive ligand-blocking assays and absolute qPCR, we demonstrated that the SR-A competitive ligands drastically reduced the quantities of cell-associated viral loads in Frog cells. Moreover, inducing the expression of a human SR-AI in an SR-A null cell line significantly increased FV3–cell association. Together, our results indicate that SR-As are utilized by FV3 during the cellular entry process.
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immune roles of amphibian xenopus laevis tadpole granulocytes during Frog Virus 3 ranaVirus infections
Developmental and Comparative Immunology, 2017Co-Authors: Daphne V Koubourli, Emily S Wendel, Amulya Yaparla, Jonathan R Ghaul, Leon GrayferAbstract:Infections by Frog Virus 3 (FV3) and other ranaViruses (RVs) are contributing to the amphibian declines, while the mechanisms controlling anuran tadpole susceptibility and adult Frog resistance to RVs, including the roles of polymorphonuclear granulocytes (PMNs) during anti-FV3 responses, remain largely unknown. Since amphibian kidneys represent an important FV3 target, the inability of amphibian (Xenopus laevis) tadpoles to mount effective kidney inflammatory responses to FV3 is thought to contribute to their susceptibility. Here we demonstrate that a recombinant X. laevis granulocyte colony-stimulating factor (G-CSF) generates PMNs with hallmark granulocyte morphology. Tadpole pretreatment with G-CSF prior to FV3 infection reduces animal kidney FV3 loads and extends their survival. Moreover, G-CSF-derived PMNs are resistant to FV3 infection and express high levels of TNFα in response to this Virus. Notably, FV3-infected tadpoles fail to recruit G-CSFR expressing granulocytes into their kidneys, suggesting that they lack an integral inflammatory effector population at this site.
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Characterization of Frog Virus 3 knockout mutants lacking putative virulence genes.
Virology, 2015Co-Authors: Francisco De Jesús Andino, Leon Grayfer, Guangchun Chen, V. Gregory Chinchar, Eva-stina Edholm, Jacques RobertAbstract:To identify ranaVirus virulence genes, we engineered Frog Virus 3 (FV3) knockout (KO) mutants defective for a putative viral caspase activation and recruitment domain-containing (CARD) protein (Δ64R-FV3) and a β-hydroxysteroid dehydrogenase homolog (Δ52L-FV3). Compared to wild type (WT) FV3, infection of Xenopus tadpoles with Δ64R- or Δ52L-FV3 resulted in significantly lower levels of mortality and viral replication. We further characterized these and two earlier KO mutants lacking the immediate-early18kDa protein (FV3-Δ18K) or the truncated viral homolog of eIF-2α (FV3-ΔvIF-2α). All KO mutants replicated as well as WT-FV3 in non-amphibian cell lines, whereas in Xenopus A6 kidney cells replication of ΔvCARD-, ΔvβHSD- and ΔvIF-2α-FV3 was markedly reduced. Furthermore, Δ64R- and ΔvIF-2α-FV3 were more sensitive to interferon than WT and Δ18-FV3. Notably, Δ64R-, Δ18K- and ΔvIF-2α- but not Δ52L-FV3 triggered more apoptosis than WT FV3. These data suggest that vCARD (64R) and vβ-HSD (52L) genes contribute to viral pathogenesis.
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Inflammation-induced reactivation of the ranaVirus Frog Virus 3 in asymptomatic Xenopus laevis.
PLoS ONE, 2014Co-Authors: Jacques Robert, Eva-stina Edholm, Leon Grayfer, Brian M. Ward, Francisco De Jesús AndinoAbstract:Natural infections of ectothermic vertebrates by ranaViruses (RV, family Iridoviridae) are rapidly increasing, with an alarming expansion of RV tropism and resulting die-offs of numerous animal populations. Notably, infection studies of the amphibian Xenopus laevis with the ranaVirus Frog Virus 3 (FV3) have revealed that although the adult Frog immune system is efficient at controlling RV infections, residual quiescent Virus can be detected in mononuclear phagocytes of otherwise asymptomatic animals following the resolution of RV infections. It is noteworthy that macrophage-lineage cells are now believed to be a critical element in the RV infection strategy. In the present work, we report that inflammation induced by peritoneal injection of heat-killed bacteria in asymptomatic Frogs one month after infection with FV3 resulted in viral reactivation including detectable viral DNA and viral gene expression in otherwise asymptomatic Frogs. FV3 reactivation was most prominently detected in kidneys and in peritoneal HAM56+ mononuclear phagocytes. Notably, unlike adult Frogs that typically clear primary FV3 infections, a proportion of the animals succumbed to the reactivated FV3 infection, indicating that previous exposure does not provide protection against subsequent reactivation in these animals.
Christopher J Kyle - One of the best experts on this subject based on the ideXlab platform.
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High prevalence of subclinical Frog Virus 3 infection in freshwater turtles of Ontario, Canada.
Virology, 2020Co-Authors: Sue Jacqueline Carstairs, Christopher J Kyle, Sibelle T VilacaAbstract:Abstract RanaViruses have been associated with chelonian mortality. In Canada, the first two cases of ranaVirus were detected in turtles in 2018 in Ontario, although a subsequent survey of its prevalence failed to detect additional positive cases. To confirm the prevalence of ranaVirus in turtles in Ontario, we used a more sensitive method to investigate if lower level persistent infection was present in the population. Here we report results via a combination of qPCR, PCR, Sanger sequencing and genome sequencing from turtles from across Ontario, with no clinical signs of illness. We found 2 positives with high viral load and 5 positives with low viral load. Histopathology found subtle histological changes. DNA sequences identified two types of Frog Virus 3 (FV3), and genome sequencing identified a ranaVirus similar to wild-type FV3. Our results show that the Virus has been present in Ontario’s turtles as subclinical infections.
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Frog Virus 3 genomes reveal prevalent recombination between ranaVirus lineages and their origins in canada
Journal of Virology, 2019Co-Authors: Sibelle T Vilaca, Craig R. Brunetti, Joefelix Bienentreu, David Lesbarreres, Dennis L Murray, Christopher J KyleAbstract:RanaViruses are pathogens associated with the decline of amphibian populations across much of their distribution. In North America, Frog Virus 3 (FV3) is a widely distributed pathogen with wild populations of amphibians harboring different lineages and putative recombinants between FV3 and common midwife toad Virus (CMTV). These recombinants have higher pathogenicity, and CMTV-derived genes associated with virulence are reported in wild strains in Canada. However, while FV3 is linked to amphibian die-offs in North America, CMTVs have been reported only in commercial Frog farms in North America. We sequenced complete genomes of 18 FV3 isolates from three amphibian species to characterize genetic diversity of the lineages in Canada and infer possible recombinant regions. The 18 FV3 isolates displayed different signals of recombination, varying from none to interspersed recombination with previously isolated CMTV-like Viruses. In general, most recombination breakpoints were located within open reading frames (ORFs), generating new ORFs and proteins that were a mixture between FV3 and CMTV. A combined spatial and temporal phylogeny suggests the presence of the FV3 lineage in Canada is relatively contemporary (<100 years), corroborating the hypothesis that both CMTV- and FV3-like Viruses spread to North America when the international commercial amphibian trade started. Our results highlight the importance of pathogen surveillance and viral dynamics using full genomes to more clearly understand the mechanisms of disease origin and spread.IMPORTANCE Amphibian populations are declining worldwide, and these declines have been linked to a number of anthropogenic factors, including disease. Among the pathogens associated with amphibian mortality, ranaViruses have caused massive die-offs across continents. In North America, Frog Virus 3 (FV3) is a widespread ranaVirus that can infect wild and captive amphibians. In this study, we sequenced full FV3 genomes isolated from Frogs in Canada. We report widespread recombination between FV3 and common midwife toad Virus (CMTV). Phylogenies indicate a recent origin for FV3 in Canada, possibly as a result of international amphibian trade.
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Frog Virus 3 Genomes Reveal Prevalent Recombination between RanaVirus Lineages and Their Origins in Canada.
Journal of Virology, 2019Co-Authors: Sibelle T Vilaca, Craig R. Brunetti, Joefelix Bienentreu, David Lesbarreres, Dennis L Murray, Christopher J KyleAbstract:RanaViruses are pathogens associated with the decline of amphibian populations across much of their distribution. In North America, Frog Virus 3 (FV3) is a widely distributed pathogen with wild populations of amphibians harboring different lineages and putative recombinants between FV3 and common midwife toad Virus (CMTV). These recombinants have higher pathogenicity, and CMTV-derived genes associated with virulence are reported in wild strains in Canada. However, while FV3 is linked to amphibian die-offs in North America, CMTVs have been reported only in commercial Frog farms in North America. We sequenced complete genomes of 18 FV3 isolates from three amphibian species to characterize genetic diversity of the lineages in Canada and infer possible recombinant regions. The 18 FV3 isolates displayed different signals of recombination, varying from none to interspersed recombination with previously isolated CMTV-like Viruses. In general, most recombination breakpoints were located within open reading frames (ORFs), generating new ORFs and proteins that were a mixture between FV3 and CMTV. A combined spatial and temporal phylogeny suggests the presence of the FV3 lineage in Canada is relatively contemporary (
Gregory V Chinchar - One of the best experts on this subject based on the ideXlab platform.
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Frog Virus 3 mediated translational shut off Frog Virus 3 messages are translationally more efficient than host and heterologous viral messages under conditions of increased translational stress
Virus Research, 1990Co-Authors: Gregory V ChincharAbstract:Frog Virus 3 rapidly and selectively blocks host cell translation while synthesizing more than 60 Virus-specific polypeptides. Previous work indicated that Virus infection led to activation of a kinase that phosphorylated and, as a consequence, inactivated eIF-2. Although phosphorylation of eIF-2 could explain the rapid decline in host cell translation, it could not explain how viral protein synthesis persisted in the face of host shut-off. To explain this phenomenon, we speculated that viral messages, either as a consequence of their higher translational efficiency or their greater abundance, were able to outcompete host messages for the remaining translational initiation complexes. To test this hypothesis, the relative translational efficiency of three characteristic FV3 messages was measured against that of several model messages. Translational efficiency was determined by monitoring the resistance (and hence the competitiveness) of a given transcript to increasing concentrations of salt in vitro and in vivo. In both rabbit reticulocyte lysates and wheat germ extracts, FV3 messages were more resistant to supra-optimal concentrations of potassium acetate than globin message and three BMV transcripts. In vivo, FV3 polypeptides were synthesized in the presence of salt concentrations that blocked host cell protein synthesis. These results suggest that the selective translation of FV3 messages in Virus-infected cells may partly be due to the higher translational efficiency of viral messages. Structural features that contribute to translational efficiency are discussed.
Sibelle T Vilaca - One of the best experts on this subject based on the ideXlab platform.
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High prevalence of subclinical Frog Virus 3 infection in freshwater turtles of Ontario, Canada.
Virology, 2020Co-Authors: Sue Jacqueline Carstairs, Christopher J Kyle, Sibelle T VilacaAbstract:Abstract RanaViruses have been associated with chelonian mortality. In Canada, the first two cases of ranaVirus were detected in turtles in 2018 in Ontario, although a subsequent survey of its prevalence failed to detect additional positive cases. To confirm the prevalence of ranaVirus in turtles in Ontario, we used a more sensitive method to investigate if lower level persistent infection was present in the population. Here we report results via a combination of qPCR, PCR, Sanger sequencing and genome sequencing from turtles from across Ontario, with no clinical signs of illness. We found 2 positives with high viral load and 5 positives with low viral load. Histopathology found subtle histological changes. DNA sequences identified two types of Frog Virus 3 (FV3), and genome sequencing identified a ranaVirus similar to wild-type FV3. Our results show that the Virus has been present in Ontario’s turtles as subclinical infections.
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Frog Virus 3 genomes reveal prevalent recombination between ranaVirus lineages and their origins in canada
Journal of Virology, 2019Co-Authors: Sibelle T Vilaca, Craig R. Brunetti, Joefelix Bienentreu, David Lesbarreres, Dennis L Murray, Christopher J KyleAbstract:RanaViruses are pathogens associated with the decline of amphibian populations across much of their distribution. In North America, Frog Virus 3 (FV3) is a widely distributed pathogen with wild populations of amphibians harboring different lineages and putative recombinants between FV3 and common midwife toad Virus (CMTV). These recombinants have higher pathogenicity, and CMTV-derived genes associated with virulence are reported in wild strains in Canada. However, while FV3 is linked to amphibian die-offs in North America, CMTVs have been reported only in commercial Frog farms in North America. We sequenced complete genomes of 18 FV3 isolates from three amphibian species to characterize genetic diversity of the lineages in Canada and infer possible recombinant regions. The 18 FV3 isolates displayed different signals of recombination, varying from none to interspersed recombination with previously isolated CMTV-like Viruses. In general, most recombination breakpoints were located within open reading frames (ORFs), generating new ORFs and proteins that were a mixture between FV3 and CMTV. A combined spatial and temporal phylogeny suggests the presence of the FV3 lineage in Canada is relatively contemporary (<100 years), corroborating the hypothesis that both CMTV- and FV3-like Viruses spread to North America when the international commercial amphibian trade started. Our results highlight the importance of pathogen surveillance and viral dynamics using full genomes to more clearly understand the mechanisms of disease origin and spread.IMPORTANCE Amphibian populations are declining worldwide, and these declines have been linked to a number of anthropogenic factors, including disease. Among the pathogens associated with amphibian mortality, ranaViruses have caused massive die-offs across continents. In North America, Frog Virus 3 (FV3) is a widespread ranaVirus that can infect wild and captive amphibians. In this study, we sequenced full FV3 genomes isolated from Frogs in Canada. We report widespread recombination between FV3 and common midwife toad Virus (CMTV). Phylogenies indicate a recent origin for FV3 in Canada, possibly as a result of international amphibian trade.
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Frog Virus 3 Genomes Reveal Prevalent Recombination between RanaVirus Lineages and Their Origins in Canada.
Journal of Virology, 2019Co-Authors: Sibelle T Vilaca, Craig R. Brunetti, Joefelix Bienentreu, David Lesbarreres, Dennis L Murray, Christopher J KyleAbstract:RanaViruses are pathogens associated with the decline of amphibian populations across much of their distribution. In North America, Frog Virus 3 (FV3) is a widely distributed pathogen with wild populations of amphibians harboring different lineages and putative recombinants between FV3 and common midwife toad Virus (CMTV). These recombinants have higher pathogenicity, and CMTV-derived genes associated with virulence are reported in wild strains in Canada. However, while FV3 is linked to amphibian die-offs in North America, CMTVs have been reported only in commercial Frog farms in North America. We sequenced complete genomes of 18 FV3 isolates from three amphibian species to characterize genetic diversity of the lineages in Canada and infer possible recombinant regions. The 18 FV3 isolates displayed different signals of recombination, varying from none to interspersed recombination with previously isolated CMTV-like Viruses. In general, most recombination breakpoints were located within open reading frames (ORFs), generating new ORFs and proteins that were a mixture between FV3 and CMTV. A combined spatial and temporal phylogeny suggests the presence of the FV3 lineage in Canada is relatively contemporary (
