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Wahltinez SJ, Byrne M, Stacy NI. Coelomic fluid of asteroid echinoderms: Current knowledge and future perspectives on its utility for disease and mortality investigations. Vet Pathol 2023; 60:547-559. [PMID: 37264636 DOI: 10.1177/03009858231176563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Coelomic fluid surrounds the internal organs of asteroid echinoderms (asteroids, otherwise known as sea stars or starfish) and plays an essential role in the immune system, as well as in the transport of respiratory gases, nutrients, waste products, and reproductive mediators. Due to its importance in physiology and accessibility for nonlethal diagnostic sampling, coelomic fluid of asteroids provides an excellent sample matrix for health evaluations and can be particularly useful in disease and mortality investigations. This is especially important in light of recent increases in the number of affected individuals and species, larger geographic scope, and increased observed frequency of sea star wasting events compared with historic accounts of wasting. This review summarizes the current knowledge about coelomocytes, the effector cell of the asteroid immune system; coelomic fluid electrolytes, osmolality, acid-base status and respiratory gases, and microbiota; and genomic, transcriptomic, and proteomic investigations of coelomic fluid. The utility of coelomic fluid analysis for assessing stressor responses, diseases, and mortality investigations is considered with knowledge gaps and future directions identified. This complex body fluid provides an exciting opportunity to increase our understanding of this unique and ecologically important group of animals.
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Affiliation(s)
| | - Maria Byrne
- The University of Sydney, Sydney, NSW, Australia
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2
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Oulhen N, Byrne M, Duffin P, Gomez-Chiarri M, Hewson I, Hodin J, Konar B, Lipp EK, Miner BG, Newton AL, Schiebelhut LM, Smolowitz R, Wahltinez SJ, Wessel GM, Work TM, Zaki HA, Wares JP. A Review of Asteroid Biology in the Context of Sea Star Wasting: Possible Causes and Consequences. THE BIOLOGICAL BULLETIN 2022; 243:50-75. [PMID: 36108034 PMCID: PMC10642522 DOI: 10.1086/719928] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
AbstractSea star wasting-marked in a variety of sea star species as varying degrees of skin lesions followed by disintegration-recently caused one of the largest marine die-offs ever recorded on the west coast of North America, killing billions of sea stars. Despite the important ramifications this mortality had for coastal benthic ecosystems, such as increased abundance of prey, little is known about the causes of the disease or the mechanisms of its progression. Although there have been studies indicating a range of causal mechanisms, including viruses and environmental effects, the broad spatial and depth range of affected populations leaves many questions remaining about either infectious or non-infectious mechanisms. Wasting appears to start with degradation of mutable connective tissue in the body wall, leading to disintegration of the epidermis. Here, we briefly review basic sea star biology in the context of sea star wasting and present our current knowledge and hypotheses related to the symptoms, the microbiome, the viruses, and the associated environmental stressors. We also highlight throughout the article knowledge gaps and the data needed to better understand sea star wasting mechanistically, its causes, and potential management.
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Affiliation(s)
- Nathalie Oulhen
- Department of Molecular and Cell Biology and Biochemistry, Brown University, Providence, Rhode Island
| | - Maria Byrne
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Paige Duffin
- Department of Genetics, University of Georgia, Athens, Georgia
| | - Marta Gomez-Chiarri
- Department of Fisheries, Animal, and Veterinary Science, University of Rhode Island, Kingston, Rhode Island
| | - Ian Hewson
- Department of Microbiology, Cornell University, Ithaca, New York
| | - Jason Hodin
- Friday Harbor Labs, University of Washington, Friday Harbor, Washington
| | - Brenda Konar
- College of Fisheries and Ocean Sciences, University of Alaska, Fairbanks, Alaska
| | - Erin K. Lipp
- Department of Environmental Health Science, University of Georgia, Athens, Georgia
| | - Benjamin G. Miner
- Department of Biology, Western Washington University, Bellingham, Washington
| | | | - Lauren M. Schiebelhut
- Department of Life and Environmental Sciences, University of California, Merced, California
| | - Roxanna Smolowitz
- Department of Biology and Marine Biology, Roger Williams University, Bristol, Rhode Island
| | - Sarah J. Wahltinez
- Department of Comparative, Diagnostic, and Population Medicine, College of Veterinary Medicine, University of Florida, Gainesville, Florida
| | - Gary M. Wessel
- Department of Molecular and Cell Biology and Biochemistry, Brown University, Providence, Rhode Island
| | - Thierry M. Work
- US Geological Survey, National Wildlife Health Center, Honolulu Field Station, Honolulu, Hawaii
| | - Hossam A. Zaki
- Department of Molecular and Cell Biology and Biochemistry, Brown University, Providence, Rhode Island
| | - John P. Wares
- Department of Genetics, University of Georgia, Athens, Georgia
- Odum School of Ecology, University of Georgia, Athens, Georgia
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Smith S, Hewson I, Collins P. The first records of sea star wasting disease in Crossaster papposus in Europe. Biol Lett 2022; 18:20220197. [PMID: 35892208 PMCID: PMC9326281 DOI: 10.1098/rsbl.2022.0197] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Sea star wasting disease (SSWD) refers to a suite of gross pathological signs observed in Asteroidea species. It presents to varying degrees as abnormal posture, epidermal ulceration, arm autotomy and eversion of viscera. We report observations of SSWD in the sunstar Crossaster papposus, the first observations of its kind in Europe. While the exact cause of SSWD remains unknown, studies have proposed pathogenic and environmental-stress pathways for disease outbreaks. Although the present observations do not support a precise aetiology, the presence of SSWD in a keystone predator may have wide reaching ecological and management implications.
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Affiliation(s)
- Samuel Smith
- School of Biological Sciences, Queen's University Belfast, 19 Chlorine Gardens, Belfast BT9 5DL, UK
| | - Ian Hewson
- Department of Microbiology, Cornell University, Wing Hall 403, Ithaca, NY 14850, USA
| | - Patrick Collins
- School of Biological Sciences, Queen's University Belfast, 19 Chlorine Gardens, Belfast BT9 5DL, UK
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Abstract
Echinoderms are a phylum of marine invertebrates that include model organisms, keystone species, and animals commercially harvested for seafood. Despite their scientific, ecological, and economic importance, there is little known about the diversity of RNA viruses that infect echinoderms compared to other invertebrates. We screened over 900 transcriptomes and viral metagenomes to characterize the RNA virome of 38 echinoderm species from all five classes (Crinoidea, Holothuroidea, Asteroidea, Ophiuroidea and Echinoidea). We identified 347 viral genome fragments that were classified to genera and families within nine viral orders - Picornavirales, Durnavirales, Martellivirales, Nodamuvirales, Reovirales, Amarillovirales, Ghabrivirales, Mononegavirales, and Hepelivirales. We compared the relative viral representation across three life stages (embryo, larvae, adult) and characterized the gene content of contigs which encoded complete or near-complete genomes. The proportion of viral reads in a given transcriptome was not found to significantly differ between life stages though the majority of viral contigs were discovered from transcriptomes of adult tissue. This study illuminates the biodiversity of RNA viruses from echinoderms, revealing the occurrence of viral groups in natural populations.
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Affiliation(s)
- Elliot W Jackson
- Department of Microbiology, Cornell University, Ithaca, NY, USA.,Scripps Institution of Oceanography, University of California San Diego, La Jolla CA, USA
| | - Roland C Wilhelm
- School of Integrative Plant Science, Bradfield Hall, Cornell University, Ithaca, NY, USA
| | - Daniel H Buckley
- Department of Microbiology, Cornell University, Ithaca, NY, USA.,School of Integrative Plant Science, Bradfield Hall, Cornell University, Ithaca, NY, USA
| | - Ian Hewson
- Department of Microbiology, Cornell University, Ithaca, NY, USA
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Work TM, Weatherby TM, DeRito CM, Besemer RM, Hewson I. Sea star wasting disease pathology in Pisaster ochraceus shows a basal-to-surface process affecting color phenotypes differently. DISEASES OF AQUATIC ORGANISMS 2021; 145:21-33. [PMID: 34080580 DOI: 10.3354/dao03598] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Sea star wasting disease (SSWD) refers to a suite of poorly described non-specific clinical signs including abnormal posture, epidermal ulceration, and limb autotomy (sloughing) causing mortalities of over 20 species of sea stars and subsequent ecological shifts throughout the northeastern Pacific. While SSWD is widely assumed to be infectious, with environmental conditions facilitating disease progression, few data exist on cellular changes associated with the disease. This is unfortunate, because such observations could inform mechanisms of disease pathogenesis and host susceptibility. Here, we replicated SSWD by exposing captive Pisaster ochraceus to a suite of non-infectious organic substances and show that development of gross lesions is a basal-to-surface process involving inflammation (e.g. infiltration of coelomocytes) of ossicles and mutable collagenous tissue, leading to epidermal ulceration. Affected sea stars also manifest increases in a heretofore undocumented coelomocyte type, spindle cells, that might be a useful marker of inflammation in this species. Finally, compared to purple morphs, orange P. ochraceus developed more severe lesions but survived longer. Longer-lived, and presumably more visible, severely-lesioned orange sea stars could have important demographic implications in terms of detectability of lesioned animals in the wild and measures of apparent prevalence of disease.
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Affiliation(s)
- Thierry M Work
- US Geological Survey, National Wildlife Health Center, Honolulu Field Station, Honolulu, HI 96850, USA
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Hewson I, Sewell MA. Surveillance of densoviruses and mesomycetozoans inhabiting grossly normal tissues of three Aotearoa New Zealand asteroid species. PLoS One 2021; 16:e0241026. [PMID: 33886557 PMCID: PMC8061988 DOI: 10.1371/journal.pone.0241026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 03/23/2021] [Indexed: 11/19/2022] Open
Abstract
Asteroid wasting events and mass mortality have occurred for over a century. We currently lack a fundamental understanding of the microbial ecology of asteroid disease, with disease investigations hindered by sparse information about the microorganisms associated with grossly normal specimens. We surveilled viruses and protists associated with grossly normal specimens of three asteroid species (Patiriella regularis, Stichaster australis, Coscinasterias muricata) on the North Island / Te Ika-a-Māui, Aotearoa New Zealand, using metagenomes prepared from virus and ribosome-sized material. We discovered several densovirus-like genome fragments in our RNA and DNA metagenomic libraries. Subsequent survey of their prevalence within populations by quantitative PCR (qPCR) demonstrated their occurrence in only a few (13%) specimens (n = 36). Survey of large and small subunit rRNAs in metagenomes revealed the presence of a mesomycete (most closely matching Ichthyosporea sp.). Survey of large subunit prevalence and load by qPCR revealed that it is widely detectable (80%) and present predominately in body wall tissues across all 3 species of asteroid. Our results raise interesting questions about the roles of these microbiome constituents in host ecology and pathogenesis under changing ocean conditions.
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Affiliation(s)
- Ian Hewson
- Department of Microbiology, Cornell University, Ithaca, NY, United States of America
- * E-mail:
| | - Mary A. Sewell
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
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Guo M, Li C. Current progress on identification of virus pathogens and the antiviral effectors in echinoderms. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2021; 116:103912. [PMID: 33129884 DOI: 10.1016/j.dci.2020.103912] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 10/25/2020] [Accepted: 10/25/2020] [Indexed: 06/11/2023]
Abstract
Echinoderms are important marine organisms that live in a wide range from the intertidal zone to the abyssal zone. Members of this phylum are prone to dramatic population fluctuations that may trigger dramatic shifts in ecosystem structure. Despite the extremely complex nature of the marine environment, the immune systems of echinoderms induce a complex innate immune response to prokaryotic and eukaryotic pathogens. Previous studies showed that many echinoderm disease outbreaks were associated with specific bacteria, whereas recent scientific investigations using newly developed technologies revealed the amazing diversity of viruses in seawater. Viruses are potential pathogens of several infectious diseases of marine echinoderms. We reviewed the discovery of viruses in echinoderms and discussed the relationship between viruses and diseases for the first time. We further summarized the research progress of the potential immune-related genes and signal pathways induced by viruses and poly (I:C). Additionally, numbers of studies showed that active substances extracted from echinoderms, or the compounds synthesized from these substances, have significant antihuman virus ability. This result suggests that the active substances derived from echinoderms provide potential antiviral protection for the organism, which may provide future research directions for the antiviral immunity of echinoderms. Thus, this review also collected information on the antiviral activities of biologically active substances from echinoderms, which may pave the way for new trends in antiviral immunity for echinoderms and antiviral drugs in humans.
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Affiliation(s)
- Ming Guo
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, PR China
| | - Chenghua Li
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071, PR China.
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Aquino CA, Besemer RM, DeRito CM, Kocian J, Porter IR, Raimondi PT, Rede JE, Schiebelhut LM, Sparks JP, Wares JP, Hewson I. Evidence That Microorganisms at the Animal-Water Interface Drive Sea Star Wasting Disease. Front Microbiol 2021; 11:610009. [PMID: 33488550 PMCID: PMC7815596 DOI: 10.3389/fmicb.2020.610009] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 11/30/2020] [Indexed: 12/19/2022] Open
Abstract
Sea star wasting (SSW) disease describes a condition affecting asteroids that resulted in significant Northeastern Pacific population decline following a mass mortality event in 2013. The etiology of SSW is unresolved. We hypothesized that SSW is a sequela of microbial organic matter remineralization near respiratory surfaces, one consequence of which may be limited O2 availability at the animal-water interface. Microbial assemblages inhabiting tissues and at the asteroid-water interface bore signatures of copiotroph proliferation before SSW onset, followed by the appearance of putatively facultative and strictly anaerobic taxa at the time of lesion genesis and as animals died. SSW lesions were induced in Pisaster ochraceus by enrichment with a variety of organic matter (OM) sources. These results together illustrate that depleted O2 conditions at the animal-water interface may be established by heterotrophic microbial activity in response to organic matter loading. SSW was also induced by modestly (∼39%) depleted O2 conditions in aquaria, suggesting that small perturbations in dissolved O2 may exacerbate the condition. SSW susceptibility between species was significantly and positively correlated with surface rugosity, a key determinant of diffusive boundary layer thickness. Tissues of SSW-affected individuals collected in 2013–2014 bore δ15N signatures reflecting anaerobic processes, which suggests that this phenomenon may have affected asteroids during mass mortality at the time. The impacts of enhanced microbial activity and subsequent O2 diffusion limitation may be more pronounced under higher temperatures due to lower O2 solubility, in more rugose asteroid species due to restricted hydrodynamic flow, and in larger specimens due to their lower surface area to volume ratios which affects diffusive respiratory potential.
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Affiliation(s)
- Citlalli A Aquino
- Department of Biology, Estuary and Ocean Science Center, San Francisco State University, Tiburon, CA, United States
| | - Ryan M Besemer
- Center for Marine Science, University of North Carolina Wilmington, Wilmington, NC, United States
| | | | - Jan Kocian
- Unaffiliated Researcher, Freeland, WA, United States
| | - Ian R Porter
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, United States
| | - Peter T Raimondi
- Institute of Marine Sciences, Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA, United States
| | - Jordan E Rede
- Department of Microbiology, Cornell University, Ithaca, NY, United States
| | - Lauren M Schiebelhut
- Life and Environmental Sciences, University of California, Merced, Merced, CA, United States
| | - Jed P Sparks
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, United States
| | - John P Wares
- Department of Genetics, University of Georgia, Athens, GA, United States
| | - Ian Hewson
- Department of Microbiology, Cornell University, Ithaca, NY, United States
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Diversity of Sea Star-Associated Densoviruses and Transcribed Endogenous Viral Elements of Densovirus Origin. J Virol 2020; 95:JVI.01594-20. [PMID: 32967964 PMCID: PMC7737747 DOI: 10.1128/jvi.01594-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 09/17/2020] [Indexed: 02/07/2023] Open
Abstract
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. 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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Hewson I, Aquino CA, DeRito CM. Virome Variation during Sea Star Wasting Disease Progression in Pisaster ochraceus (Asteroidea, Echinodermata). Viruses 2020; 12:E1332. [PMID: 33233680 PMCID: PMC7699681 DOI: 10.3390/v12111332] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 11/08/2020] [Accepted: 11/19/2020] [Indexed: 12/27/2022] Open
Abstract
Sea star wasting disease (SSWD) is a condition that has affected asteroids for over 120 years, yet mechanistic understanding of this wasting etiology remains elusive. We investigated temporal virome variation in two Pisaster ochraceus specimens that wasted in the absence of external stimuli and two specimens that did not experience SSWD for the duration of our study, and compared viromes of wasting lesion margin tissues to both artificial scar margins and grossly normal tissues over time. Global assembly of all SSWD-affected tissue libraries resulted in 24 viral genome fragments represented in >1 library. Genome fragments mostly matched densoviruses and picornaviruses with fewer matching nodaviruses, and a sobemovirus. Picornavirus-like and densovirus-like genome fragments were most similar to viral genomes recovered in metagenomic study of other marine invertebrates. Read recruitment revealed only two picornavirus-like genome fragments that recruited from only SSWD-affected specimens, but neither was unique to wasting lesions. Wasting lesion margin reads recruited to a greater number of viral genotypes (i.e., richness) than did either scar tissue and grossly normal tissue reads. Taken together, these data suggest that no single viral genome fragment was associated with SSWD. Rather, wasting lesion margins may generally support viral proliferation.
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Affiliation(s)
- Ian Hewson
- Department of Microbiology, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY 14850, USA;
| | - Citlalli A. Aquino
- Department of Biology, Estuary and Ocean Science Center, San Francisco State University, Tiburon, CA 94920, USA;
| | - Christopher M. DeRito
- Department of Microbiology, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY 14850, USA;
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Hewson I, Johnson MR, Tibbetts IR. An Unconventional Flavivirus and Other RNA Viruses in the Sea Cucumber (Holothuroidea; Echinodermata) Virome. Viruses 2020; 12:v12091057. [PMID: 32972018 PMCID: PMC7551563 DOI: 10.3390/v12091057] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 09/18/2020] [Accepted: 09/21/2020] [Indexed: 12/11/2022] Open
Abstract
Sea cucumbers (Holothuroidea; Echinodermata) are ecologically significant constituents of benthic marine habitats. We surveilled RNA viruses inhabiting eight species (representing four families) of holothurian collected from four geographically distinct locations by viral metagenomics, including a single specimen of Apostichopus californicus affected by a hitherto undocumented wasting disease. The RNA virome comprised genome fragments of both single-stranded positive sense and double stranded RNA viruses, including those assigned to the Picornavirales, Ghabrivirales, and Amarillovirales. We discovered an unconventional flavivirus genome fragment which was most similar to a shark virus. Ghabivirales-like genome fragments were most similar to fungal totiviruses in both genome architecture and homology and had likely infected mycobiome constituents. Picornavirales, which are commonly retrieved in host-associated viral metagenomes, were similar to invertebrate transcriptome-derived picorna-like viruses. The greatest number of viral genome fragments was recovered from the wasting A. californicus library compared to the asymptomatic A. californicus library. However, reads from the asymptomatic library recruited to nearly all recovered wasting genome fragments, suggesting that they were present but not well represented in the grossly normal specimen. These results expand the known host range of flaviviruses and suggest that fungi and their viruses may play a role in holothurian ecology.
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Affiliation(s)
- Ian Hewson
- Department of Microbiology, Cornell University, Ithaca, NY 14853, USA;
- Correspondence: ; Tel.: +1-607-255-0151
| | | | - Ian R. Tibbetts
- School of Biological Sciences, University of Queensland, St Lucia, Brisbane, QLD 4072, Australia;
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