The Experts below are selected from a list of 1137 Experts worldwide ranked by ideXlab platform
Ian Hewson - One of the best experts on this subject based on the ideXlab platform.
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Diversity of sea star-associated Densoviruses and transcribed endogenized viral elements of Densovirus origin
Journal of virology, 2020Co-Authors: Elliot W. Jackson, Joseph K Gaydos, Roland C. Wilhelm, Mitchell R. Johnson, Holly L. Lutz, Isabelle Danforth, Michael W. Hart, Ian HewsonAbstract:A viral etiology of sea star wasting syndrome (SSWS) was originally explored with virus-sized material challenge experiments, field surveys, and metagenomics, leading to the conclusion that a Densovirus is the predominant DNA virus associated with this syndrome and, thus, the most promising viral candidate pathogen. Single-stranded DNA viruses are, however, highly diverse and pervasive among eukaryotic organisms, which we hypothesize may confound the association between Densoviruses and SSWS. To test this hypothesis and assess the association of Densoviruses with SSWS, we compiled past metagenomic data with new metagenomic-derived viral genomes from sea stars collected from Antarctica, California, Washington, and Alaska. We used 179 publicly available sea star transcriptomes to complement our approaches for Densovirus discovery. Lastly, we focus the study on sea star-associated Densovirus (SSaDV), the first sea star Densovirus discovered, by documenting its biogeography and putative tissue tropism. Transcriptomes contained only endogenized Densovirus elements similar to the NS1 gene, while numerous extant densoviral genomes were recovered from viral metagenomes. SSaDV was associated with nearly all tested species from southern California to Alaska, and in contrast to previous work, we show that SSaDV is one genotype among a high diversity of Densoviruses present in sea stars across the West Coast of the United States and globally that are commonly associated with grossly normal (i.e., healthy or asymptomatic) animals. The diversity and ubiquity of these viruses in sea stars confound the original hypothesis that one Densovirus is the etiological agent of SSWS.IMPORTANCE The primary interest in sea star Densoviruses, specifically SSaDV, has been their association with sea star wasting syndrome (SSWS), a disease that has decimated sea star populations across the West Coast of the United States since 2013. The association of SSaDV with SSWS was originally drawn from metagenomic analysis, which was further studied through field surveys using quantitative PCR (qPCR), with the conclusion that it was the most likely viral candidate in the metagenomic data based on its representation in symptomatic sea stars compared to asymptomatic sea stars. We reexamined the original metagenomic data with additional genomic data sets and found that SSaDV was 1 of 10 Densoviruses present in the original data set and was no more represented in symptomatic sea stars than in asymptomatic sea stars. Instead, SSaDV appears to be a widespread, generalist virus that exists among a large diversity of Densoviruses present in sea star populations.
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Diversity of sea star-associated Densoviruses and transcribed endogenized viral elements of Densovirus origin
2020Co-Authors: Elliot W. Jackson, Joseph K Gaydos, Roland C. Wilhelm, Mitchell R. Johnson, Holly L. Lutz, Isabelle Danforth, Michael W. Hart, Ian HewsonAbstract:A viral etiology of Sea Star Wasting Syndrome (SSWS) has been largely explored using metagenomics leading to the conclusion that a Densovirus is the predominant DNA virus associated with this syndrome, and, thus, the most promising viral candidate pathogen. Single-stranded DNA viruses are however highly diverse and pervasive among eukaryotic organisms which we hypothesize may confound the association between Densoviruses and SSWS in sea stars. To test this hypothesis and assess the association of Densoviruses to SSWS, we compiled past metagenomic data with new metagenomic-derived viral genomes from sea stars collected from Antarctica, California, Washington, and Alaska. We used 179 publicly available sea star transcriptomes to complement our approaches for Densovirus discovery. Lastly, we focus the study to SSaDV, the first sea star Densovirus discovered, by documenting its biogeography and putative tissue tropism. Transcriptomes contained mostly endogenized Densovirus elements similar to the NS1 gene, while >30 complete and near-complete densoviral genomes were recovered from viral metagenomes. SSaDV was associated with nearly all tested species from southern California to Alaska, and in contrast to previous work, we show SSaDV is one genotype among a high diversity of Densoviruses present in sea stars across the west coast of the United States and globally that are commonly associated with grossly normal (i.e. healthy or asymptomatic) animals. The diversity and ubiquity of these viruses in wild sea stars confounds the original hypothesis that one Densovirus was the etiologic agent of SSWD. ImportanceThe primary interest in sea star Densoviruses, specifically SSaDV, has been their association with Sea Star Wasting Syndrome (SSWS), a disease that has decimated sea star populations across the west coast of the United States since 2013. The association of SSaDV to SSWS was originally drawn from metagenomic analyses concluding that it was (1) the only Densovirus present in the metagenomic data and (2) the most likely viral candidate based on representation in symptomatic sea stars. We reassessed the original metagenomic data with additional genomic datasets and found that SSaDV was one of ten Densoviruses present in the original dataset and was no more represented in symptomatic sea stars than in asymptomatic sea stars. Instead, SSaDV appears to be a widespread, generalist virus that exists among a large diversity of Densoviruses present in sea star populations.
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A Highly Prevalent and Pervasive Densovirus Discovered among Sea Stars from the North American Atlantic Coast.
Applied and environmental microbiology, 2020Co-Authors: Elliot W. Jackson, Mitchell R. Johnson, Charles Pepe-ranney, Daniel L. Distel, Ian HewsonAbstract:ABSTRACT The etiology of sea star wasting syndrome is hypothesized to be caused by a Densovirus, sea star-associated Densovirus (SSaDV), that has previously been reported on the Pacific and Atlantic Coasts of the United States. In this study, we reevaluated the presence of SSaDV among sea stars from the North American Atlantic Coast and in doing so discovered a novel Densovirus that we have named Asterias forbesi-associated Densovirus (AfaDV), which shares 78% nucleotide pairwise identity with SSaDV. In contrast to previous studies, SSaDV was not detected in sea stars from the North American Atlantic Coast. Using a variety of PCR-based techniques, we investigated the tissue tropism, host specificity, and prevalence of AfaDV among populations of sea stars at five locations along the Atlantic Coast. AfaDV was detected in three sea star species (Asterias forbesi, Asterias rubens, and Henricia sp.) found in this region and was highly prevalent (>80% of individuals tested; n = 134), among sampled populations. AfaDV was detected in the body wall, gonads, and pyloric caeca (digestive gland) of specimens but was not detected in their coelomic fluid. A significant difference in viral load (copies mg−1) was found between tissue types, with the pyloric caeca having the highest viral loads. Further investigation of Asterias forbesi gonad tissue found germ line cells (oocytes) to be virus positive, suggesting a potential route of vertical transmission. Taken together, these observations show that the presence of AfaDV is not an indicator of sea star wasting syndrome because AfaDV is a common constituent of these animals’ microbiome, regardless of health. IMPORTANCE Sea star wasting syndrome is a disease primarily observed on the Pacific and Atlantic Coasts of North America that has significantly impacted sea star populations. The etiology of this disease is unknown, although it is hypothesized to be caused by a Densovirus, SSaDV. However, previous studies have not found a correlation between SSaDV and sea star wasting syndrome on the North American Atlantic Coast. This study suggests that this observation may be explained by the presence of a genetically similar Densovirus, AfaDV, that may have confounded previous studies. SSaDV was not present in sea stars screened in this study, and instead, AfaDV was commonly found in sea star populations across the New England region, with no apparent signs of disease. These results suggest that sea star Densoviruses may be common constituents of the animals’ microbiome, and the diversity and extent of these viruses among wild populations may be greater than previously recognized.
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Table2.DOCX
2018Co-Authors: Ian Hewson, Jason B Button, Kalia S. I. Bistolas, Eva Quijano M. Cardé, Parker J. Foster, Jacob M. Flanzenbaum, Jan Kocian, Chaunte K. LewisAbstract:Sea Star Wasting Disease (SSWD) describes a suite of disease signs that affected >20 species of asteroid since 2013 along a broad geographic range from the Alaska Peninsula to Baja California. Previous work identified the Sea Star associated Densovirus (SSaDV) as the best candidate pathogen for SSWD in three species of common asteroid (Pycnopodia helianthoides, Pisaster ochraceus, and Evasterias troscheli), and virus-sized material (
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Presentation1.PDF
2018Co-Authors: Ian Hewson, Jason B Button, Kalia S. I. Bistolas, Eva Quijano M. Cardé, Parker J. Foster, Jacob M. Flanzenbaum, Jan Kocian, Chaunte K. LewisAbstract:Sea Star Wasting Disease (SSWD) describes a suite of disease signs that affected >20 species of asteroid since 2013 along a broad geographic range from the Alaska Peninsula to Baja California. Previous work identified the Sea Star associated Densovirus (SSaDV) as the best candidate pathogen for SSWD in three species of common asteroid (Pycnopodia helianthoides, Pisaster ochraceus, and Evasterias troscheli), and virus-sized material (
Joseph K Gaydos - One of the best experts on this subject based on the ideXlab platform.
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Diversity of sea star-associated Densoviruses and transcribed endogenized viral elements of Densovirus origin
Journal of virology, 2020Co-Authors: Elliot W. Jackson, Joseph K Gaydos, Roland C. Wilhelm, Mitchell R. Johnson, Holly L. Lutz, Isabelle Danforth, Michael W. Hart, Ian HewsonAbstract:A viral etiology of sea star wasting syndrome (SSWS) was originally explored with virus-sized material challenge experiments, field surveys, and metagenomics, leading to the conclusion that a Densovirus is the predominant DNA virus associated with this syndrome and, thus, the most promising viral candidate pathogen. Single-stranded DNA viruses are, however, highly diverse and pervasive among eukaryotic organisms, which we hypothesize may confound the association between Densoviruses and SSWS. To test this hypothesis and assess the association of Densoviruses with SSWS, we compiled past metagenomic data with new metagenomic-derived viral genomes from sea stars collected from Antarctica, California, Washington, and Alaska. We used 179 publicly available sea star transcriptomes to complement our approaches for Densovirus discovery. Lastly, we focus the study on sea star-associated Densovirus (SSaDV), the first sea star Densovirus discovered, by documenting its biogeography and putative tissue tropism. Transcriptomes contained only endogenized Densovirus elements similar to the NS1 gene, while numerous extant densoviral genomes were recovered from viral metagenomes. SSaDV was associated with nearly all tested species from southern California to Alaska, and in contrast to previous work, we show that SSaDV is one genotype among a high diversity of Densoviruses present in sea stars across the West Coast of the United States and globally that are commonly associated with grossly normal (i.e., healthy or asymptomatic) animals. The diversity and ubiquity of these viruses in sea stars confound the original hypothesis that one Densovirus is the etiological agent of SSWS.IMPORTANCE The primary interest in sea star Densoviruses, specifically SSaDV, has been their association with sea star wasting syndrome (SSWS), a disease that has decimated sea star populations across the West Coast of the United States since 2013. The association of SSaDV with SSWS was originally drawn from metagenomic analysis, which was further studied through field surveys using quantitative PCR (qPCR), with the conclusion that it was the most likely viral candidate in the metagenomic data based on its representation in symptomatic sea stars compared to asymptomatic sea stars. We reexamined the original metagenomic data with additional genomic data sets and found that SSaDV was 1 of 10 Densoviruses present in the original data set and was no more represented in symptomatic sea stars than in asymptomatic sea stars. Instead, SSaDV appears to be a widespread, generalist virus that exists among a large diversity of Densoviruses present in sea star populations.
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Diversity of sea star-associated Densoviruses and transcribed endogenized viral elements of Densovirus origin
2020Co-Authors: Elliot W. Jackson, Joseph K Gaydos, Roland C. Wilhelm, Mitchell R. Johnson, Holly L. Lutz, Isabelle Danforth, Michael W. Hart, Ian HewsonAbstract:A viral etiology of Sea Star Wasting Syndrome (SSWS) has been largely explored using metagenomics leading to the conclusion that a Densovirus is the predominant DNA virus associated with this syndrome, and, thus, the most promising viral candidate pathogen. Single-stranded DNA viruses are however highly diverse and pervasive among eukaryotic organisms which we hypothesize may confound the association between Densoviruses and SSWS in sea stars. To test this hypothesis and assess the association of Densoviruses to SSWS, we compiled past metagenomic data with new metagenomic-derived viral genomes from sea stars collected from Antarctica, California, Washington, and Alaska. We used 179 publicly available sea star transcriptomes to complement our approaches for Densovirus discovery. Lastly, we focus the study to SSaDV, the first sea star Densovirus discovered, by documenting its biogeography and putative tissue tropism. Transcriptomes contained mostly endogenized Densovirus elements similar to the NS1 gene, while >30 complete and near-complete densoviral genomes were recovered from viral metagenomes. SSaDV was associated with nearly all tested species from southern California to Alaska, and in contrast to previous work, we show SSaDV is one genotype among a high diversity of Densoviruses present in sea stars across the west coast of the United States and globally that are commonly associated with grossly normal (i.e. healthy or asymptomatic) animals. The diversity and ubiquity of these viruses in wild sea stars confounds the original hypothesis that one Densovirus was the etiologic agent of SSWD. ImportanceThe primary interest in sea star Densoviruses, specifically SSaDV, has been their association with Sea Star Wasting Syndrome (SSWS), a disease that has decimated sea star populations across the west coast of the United States since 2013. The association of SSaDV to SSWS was originally drawn from metagenomic analyses concluding that it was (1) the only Densovirus present in the metagenomic data and (2) the most likely viral candidate based on representation in symptomatic sea stars. We reassessed the original metagenomic data with additional genomic datasets and found that SSaDV was one of ten Densoviruses present in the original dataset and was no more represented in symptomatic sea stars than in asymptomatic sea stars. Instead, SSaDV appears to be a widespread, generalist virus that exists among a large diversity of Densoviruses present in sea star populations.
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Densovirus associated with sea star wasting disease and mass mortality
Proceedings of the National Academy of Sciences of the United States of America, 2014Co-Authors: Ian Hewson, Jason B Button, Brent M Gudenkauf, Benjamin G Miner, Alisa L Newton, Joseph K Gaydos, Janna Wynne, Cathy L Groves, Gordon Hendler, Michael F MurrayAbstract:Abstract Populations of at least 20 asteroid species on the Northeast Pacific Coast have recently experienced an extensive outbreak of sea-star (asteroid) wasting disease (SSWD). The disease leads to behavioral changes, lesions, loss of turgor, limb autotomy, and death characterized by rapid degradation (“melting”). Here, we present evidence from experimental challenge studies and field observations that link the mass mortalities to a Densovirus (Parvoviridae). Virus-sized material (i.e., <0.2 μm) from symptomatic tissues that was inoculated into asymptomatic asteroids consistently resulted in SSWD signs whereas animals receiving heat-killed (i.e., control) virus-sized inoculum remained asymptomatic. Viral metagenomic investigations revealed the sea star-associated Densovirus (SSaDV) as the most likely candidate virus associated with tissues from symptomatic asteroids. Quantification of SSaDV during transmission trials indicated that progression of SSWD paralleled increased SSaDV load. In field surveys, SSaDV loads were more abundant in symptomatic than in asymptomatic asteroids. SSaDV could be detected in plankton, sediments and in nonasteroid echinoderms, providing a possible mechanism for viral spread. SSaDV was detected in museum specimens of asteroids from 1942, suggesting that it has been present on the North American Pacific Coast for at least 72 y. SSaDV is therefore the most promising candidate disease agent responsible for asteroid mass mortality.
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Densovirus associated with sea-star wasting disease and mass mortality
Proceedings of the National Academy of Sciences of the United States of America, 2014Co-Authors: Ian Hewson, Jason B Button, Brent M Gudenkauf, Benjamin G Miner, Alisa L Newton, Joseph K Gaydos, Janna Wynne, Cathy L Groves, Gordon Hendler, Michael F MurrayAbstract:Abstract Populations of at least 20 asteroid species on the Northeast Pacific Coast have recently experienced an extensive outbreak of sea-star (asteroid) wasting disease (SSWD). The disease leads to behavioral changes, lesions, loss of turgor, limb autotomy, and death characterized by rapid degradation (“melting”). Here, we present evidence from experimental challenge studies and field observations that link the mass mortalities to a Densovirus (Parvoviridae). Virus-sized material (i.e.,
Peter Tijssen - One of the best experts on this subject based on the ideXlab platform.
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gene expression of five different iteraDensoviruses bombyx mori Densovirus casphalia extranea Densovirus papilio polyxenes Densovirus sibine fusca Densovirus and danaus plexippus Densovirus
Journal of Virology, 2014Co-Authors: Qian Yu, Peter TijssenAbstract:IteraDensoviruses are 5-kb parvoviruses with typical J-shaped inverted terminal repeats of about 250 nucleotides and terminal hairpins of about 165 nucleotides. The single-stranded DNA genome contains several open reading frames, but their expression strategy is still unknown. Here the transcription maps and expression of the viruses in this genus were explored. As for breviDensoviruses, the two nonstructural (NS) genes were expressed by overlapping promoters with alternate transcription starts at both sides of the NS1 start codon.
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Expression strategy of Aedes albopictus Densovirus.
Journal of Virology, 2013Co-Authors: Hanh T Pham, Max Bergoin, Jozsef Szelei, Françoise-xavière Jousset, Jonathan Perreault, Hiroko Shike, Peter TijssenAbstract:The transcription map of the Aedes albopictus Densovirus (AalDNV) breviDensovirus was identified by Northern blotting, rapid amplification of cDNA ends (RACE) analysis, and RNase protection assays. AalDNV produced mRNAs of 3,359 (NS1), 3,345 (NS2), and 1,246 (VP) nucleotides. The two overlapping P7/7.4 NS promoters employed closely located alternate transcription initiation sites, positioned at either side of the NS1 initiation codon. All NS mRNAs coterminated with VP mRNA. All promoters, explored using luciferase assays, were functional in insect and human cell lines.
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Junonia coenia Densovirus (JcDNV) Genome Structure
Genome Announcements, 2013Co-Authors: Hanh T Pham, Max Bergoin, Françoise-xavière Jousset, Oanh Thi Hoang Huynh, Peter TijssenAbstract:ABSTRACT The sequence of Junonia coenia Densovirus was the first Densovirus genome sequence published, but the first published sequence contained incomplete inverted terminal repeats and ambiguous nucleotides or indels leading to an incorrect map of the open reading frames. Our sequencing of clones of the complete genome demonstrated that this virus is closely related to other viruses in the Densovirus genus.
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Iteravirus-Like Genome Organization of a Densovirus from Sibine fusca Stoll
Journal of Virology, 2012Co-Authors: Qian Yu, Gilles Fédière, Max Bergoin, Adly M. M. Abd-alla, Peter TijssenAbstract:The complete genome of Sibine fusca Densovirus was cloned and sequenced. The genome contained 5,012 nucleotides (nt), including inverted terminal repeats (ITRs) of 230 nt with terminal hairpins of 161 nt. Its DNA sequence and monosense organization with 3 open reading frames (ORFs) is typical of the genus Iteravirus in the subfamily Densovirinae of the Parvoviridae.
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Organization of the Ambisense Genome of the Helicoverpa armigera Densovirus
Journal of Virology, 2012Co-Authors: Mohamed El-far, Gilles Fédière, Max Bergoin, Jozsef Szelei, Peter TijssenAbstract:A natural Densovirus (DNV) of a serious phytophagous pest, Helicoverpa armigera, was isolated. The genome of HaDNV contained 6,039 nucleotides (nt) and included inverted terminal repeats (ITRs) of 545 nt with terminal Y-shaped hairpins of 126 nt. Its DNA sequence and ambisense organization with four typical open reading frames (ORFs) demonstrated that it belonged to the genus Densovirus in the subfamily Densovirinae of the family Parvoviridae.
Michael F Murray - One of the best experts on this subject based on the ideXlab platform.
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Densovirus associated with sea star wasting disease and mass mortality
Proceedings of the National Academy of Sciences of the United States of America, 2014Co-Authors: Ian Hewson, Jason B Button, Brent M Gudenkauf, Benjamin G Miner, Alisa L Newton, Joseph K Gaydos, Janna Wynne, Cathy L Groves, Gordon Hendler, Michael F MurrayAbstract:Abstract Populations of at least 20 asteroid species on the Northeast Pacific Coast have recently experienced an extensive outbreak of sea-star (asteroid) wasting disease (SSWD). The disease leads to behavioral changes, lesions, loss of turgor, limb autotomy, and death characterized by rapid degradation (“melting”). Here, we present evidence from experimental challenge studies and field observations that link the mass mortalities to a Densovirus (Parvoviridae). Virus-sized material (i.e., <0.2 μm) from symptomatic tissues that was inoculated into asymptomatic asteroids consistently resulted in SSWD signs whereas animals receiving heat-killed (i.e., control) virus-sized inoculum remained asymptomatic. Viral metagenomic investigations revealed the sea star-associated Densovirus (SSaDV) as the most likely candidate virus associated with tissues from symptomatic asteroids. Quantification of SSaDV during transmission trials indicated that progression of SSWD paralleled increased SSaDV load. In field surveys, SSaDV loads were more abundant in symptomatic than in asymptomatic asteroids. SSaDV could be detected in plankton, sediments and in nonasteroid echinoderms, providing a possible mechanism for viral spread. SSaDV was detected in museum specimens of asteroids from 1942, suggesting that it has been present on the North American Pacific Coast for at least 72 y. SSaDV is therefore the most promising candidate disease agent responsible for asteroid mass mortality.
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Densovirus associated with sea-star wasting disease and mass mortality
Proceedings of the National Academy of Sciences of the United States of America, 2014Co-Authors: Ian Hewson, Jason B Button, Brent M Gudenkauf, Benjamin G Miner, Alisa L Newton, Joseph K Gaydos, Janna Wynne, Cathy L Groves, Gordon Hendler, Michael F MurrayAbstract:Abstract Populations of at least 20 asteroid species on the Northeast Pacific Coast have recently experienced an extensive outbreak of sea-star (asteroid) wasting disease (SSWD). The disease leads to behavioral changes, lesions, loss of turgor, limb autotomy, and death characterized by rapid degradation (“melting”). Here, we present evidence from experimental challenge studies and field observations that link the mass mortalities to a Densovirus (Parvoviridae). Virus-sized material (i.e.,
Elliot W. Jackson - One of the best experts on this subject based on the ideXlab platform.
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Diversity of sea star-associated Densoviruses and transcribed endogenized viral elements of Densovirus origin
Journal of virology, 2020Co-Authors: Elliot W. Jackson, Joseph K Gaydos, Roland C. Wilhelm, Mitchell R. Johnson, Holly L. Lutz, Isabelle Danforth, Michael W. Hart, Ian HewsonAbstract:A viral etiology of sea star wasting syndrome (SSWS) was originally explored with virus-sized material challenge experiments, field surveys, and metagenomics, leading to the conclusion that a Densovirus is the predominant DNA virus associated with this syndrome and, thus, the most promising viral candidate pathogen. Single-stranded DNA viruses are, however, highly diverse and pervasive among eukaryotic organisms, which we hypothesize may confound the association between Densoviruses and SSWS. To test this hypothesis and assess the association of Densoviruses with SSWS, we compiled past metagenomic data with new metagenomic-derived viral genomes from sea stars collected from Antarctica, California, Washington, and Alaska. We used 179 publicly available sea star transcriptomes to complement our approaches for Densovirus discovery. Lastly, we focus the study on sea star-associated Densovirus (SSaDV), the first sea star Densovirus discovered, by documenting its biogeography and putative tissue tropism. Transcriptomes contained only endogenized Densovirus elements similar to the NS1 gene, while numerous extant densoviral genomes were recovered from viral metagenomes. SSaDV was associated with nearly all tested species from southern California to Alaska, and in contrast to previous work, we show that SSaDV is one genotype among a high diversity of Densoviruses present in sea stars across the West Coast of the United States and globally that are commonly associated with grossly normal (i.e., healthy or asymptomatic) animals. The diversity and ubiquity of these viruses in sea stars confound the original hypothesis that one Densovirus is the etiological agent of SSWS.IMPORTANCE The primary interest in sea star Densoviruses, specifically SSaDV, has been their association with sea star wasting syndrome (SSWS), a disease that has decimated sea star populations across the West Coast of the United States since 2013. The association of SSaDV with SSWS was originally drawn from metagenomic analysis, which was further studied through field surveys using quantitative PCR (qPCR), with the conclusion that it was the most likely viral candidate in the metagenomic data based on its representation in symptomatic sea stars compared to asymptomatic sea stars. We reexamined the original metagenomic data with additional genomic data sets and found that SSaDV was 1 of 10 Densoviruses present in the original data set and was no more represented in symptomatic sea stars than in asymptomatic sea stars. Instead, SSaDV appears to be a widespread, generalist virus that exists among a large diversity of Densoviruses present in sea star populations.
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Diversity of sea star-associated Densoviruses and transcribed endogenized viral elements of Densovirus origin
2020Co-Authors: Elliot W. Jackson, Joseph K Gaydos, Roland C. Wilhelm, Mitchell R. Johnson, Holly L. Lutz, Isabelle Danforth, Michael W. Hart, Ian HewsonAbstract:A viral etiology of Sea Star Wasting Syndrome (SSWS) has been largely explored using metagenomics leading to the conclusion that a Densovirus is the predominant DNA virus associated with this syndrome, and, thus, the most promising viral candidate pathogen. Single-stranded DNA viruses are however highly diverse and pervasive among eukaryotic organisms which we hypothesize may confound the association between Densoviruses and SSWS in sea stars. To test this hypothesis and assess the association of Densoviruses to SSWS, we compiled past metagenomic data with new metagenomic-derived viral genomes from sea stars collected from Antarctica, California, Washington, and Alaska. We used 179 publicly available sea star transcriptomes to complement our approaches for Densovirus discovery. Lastly, we focus the study to SSaDV, the first sea star Densovirus discovered, by documenting its biogeography and putative tissue tropism. Transcriptomes contained mostly endogenized Densovirus elements similar to the NS1 gene, while >30 complete and near-complete densoviral genomes were recovered from viral metagenomes. SSaDV was associated with nearly all tested species from southern California to Alaska, and in contrast to previous work, we show SSaDV is one genotype among a high diversity of Densoviruses present in sea stars across the west coast of the United States and globally that are commonly associated with grossly normal (i.e. healthy or asymptomatic) animals. The diversity and ubiquity of these viruses in wild sea stars confounds the original hypothesis that one Densovirus was the etiologic agent of SSWD. ImportanceThe primary interest in sea star Densoviruses, specifically SSaDV, has been their association with Sea Star Wasting Syndrome (SSWS), a disease that has decimated sea star populations across the west coast of the United States since 2013. The association of SSaDV to SSWS was originally drawn from metagenomic analyses concluding that it was (1) the only Densovirus present in the metagenomic data and (2) the most likely viral candidate based on representation in symptomatic sea stars. We reassessed the original metagenomic data with additional genomic datasets and found that SSaDV was one of ten Densoviruses present in the original dataset and was no more represented in symptomatic sea stars than in asymptomatic sea stars. Instead, SSaDV appears to be a widespread, generalist virus that exists among a large diversity of Densoviruses present in sea star populations.
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A Highly Prevalent and Pervasive Densovirus Discovered among Sea Stars from the North American Atlantic Coast.
Applied and environmental microbiology, 2020Co-Authors: Elliot W. Jackson, Mitchell R. Johnson, Charles Pepe-ranney, Daniel L. Distel, Ian HewsonAbstract:ABSTRACT The etiology of sea star wasting syndrome is hypothesized to be caused by a Densovirus, sea star-associated Densovirus (SSaDV), that has previously been reported on the Pacific and Atlantic Coasts of the United States. In this study, we reevaluated the presence of SSaDV among sea stars from the North American Atlantic Coast and in doing so discovered a novel Densovirus that we have named Asterias forbesi-associated Densovirus (AfaDV), which shares 78% nucleotide pairwise identity with SSaDV. In contrast to previous studies, SSaDV was not detected in sea stars from the North American Atlantic Coast. Using a variety of PCR-based techniques, we investigated the tissue tropism, host specificity, and prevalence of AfaDV among populations of sea stars at five locations along the Atlantic Coast. AfaDV was detected in three sea star species (Asterias forbesi, Asterias rubens, and Henricia sp.) found in this region and was highly prevalent (>80% of individuals tested; n = 134), among sampled populations. AfaDV was detected in the body wall, gonads, and pyloric caeca (digestive gland) of specimens but was not detected in their coelomic fluid. A significant difference in viral load (copies mg−1) was found between tissue types, with the pyloric caeca having the highest viral loads. Further investigation of Asterias forbesi gonad tissue found germ line cells (oocytes) to be virus positive, suggesting a potential route of vertical transmission. Taken together, these observations show that the presence of AfaDV is not an indicator of sea star wasting syndrome because AfaDV is a common constituent of these animals’ microbiome, regardless of health. IMPORTANCE Sea star wasting syndrome is a disease primarily observed on the Pacific and Atlantic Coasts of North America that has significantly impacted sea star populations. The etiology of this disease is unknown, although it is hypothesized to be caused by a Densovirus, SSaDV. However, previous studies have not found a correlation between SSaDV and sea star wasting syndrome on the North American Atlantic Coast. This study suggests that this observation may be explained by the presence of a genetically similar Densovirus, AfaDV, that may have confounded previous studies. SSaDV was not present in sea stars screened in this study, and instead, AfaDV was commonly found in sea star populations across the New England region, with no apparent signs of disease. These results suggest that sea star Densoviruses may be common constituents of the animals’ microbiome, and the diversity and extent of these viruses among wild populations may be greater than previously recognized.