1
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Rey-Campos M, Saco A, Novoa B, Figueras A. Transcriptomic and functional analysis of the antiviral response of mussels after a poly I:C stimulation. FISH & SHELLFISH IMMUNOLOGY 2024; 153:109867. [PMID: 39214263 DOI: 10.1016/j.fsi.2024.109867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 08/23/2024] [Accepted: 08/28/2024] [Indexed: 09/04/2024]
Abstract
The study of mussels (Mytilus galloprovincialis) has grown in importance in recent years due to their high economic value and resistance to pathogens. Because of the biological characteristics revealed by mussel genome sequencing, this species is a valuable research model. The high genomic variability and diversity, particularly in immune genes, may be responsible for their resistance to pathogens found in seawater and continuously filtered and internalized by them. These facts, combined with the lack of proven mussel susceptibility to viruses in comparison to other bivalves such as oysters, result in a lack of studies on mussel antiviral response. We used RNA-seq to examine the genomic response of mussel hemocytes after they were exposed to poly I:C, simulating immune cell contact with viral dsRNA. Apoptosis and the molecular axis IRFs/STING-IFI44/IRGC1 were identified as the two main pathways in charge of the response but we also found a modulation of lncRNAs. Finally, in order to obtain new information about the response of mussels to putative natural challenges, we used VHSV virus (Viral Hemorrhagic Septicemia Virus) to run some functional analysis and confirm poly I:C's activity as an immunomodulator in a VHSV waterborne stimulation. Both, poly I:C as well as an injury stimulus (filtered sea water injection) accelerated the viral clearance by hemocytes and altered the expression of several immune genes, including IL-17, IRF1 and viperin.
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Affiliation(s)
- Magalí Rey-Campos
- Institute of Marine Research (IIM-CSIC), Eduardo Cabello 6, 36208, Vigo, Spain
| | - Amaro Saco
- Institute of Marine Research (IIM-CSIC), Eduardo Cabello 6, 36208, Vigo, Spain
| | - Beatriz Novoa
- Institute of Marine Research (IIM-CSIC), Eduardo Cabello 6, 36208, Vigo, Spain.
| | - Antonio Figueras
- Institute of Marine Research (IIM-CSIC), Eduardo Cabello 6, 36208, Vigo, Spain.
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2
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Divilov K, Merz N, Schoolfield B, Green TJ, Langdon C. Genome-wide allele frequency studies in Pacific oyster families identify candidate genes for tolerance to ostreid herpesvirus 1 (OsHV-1). BMC Genomics 2023; 24:631. [PMID: 37872508 PMCID: PMC10594793 DOI: 10.1186/s12864-023-09744-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 10/14/2023] [Indexed: 10/25/2023] Open
Abstract
BACKGROUND Host genetics influences the development of infectious diseases in many agricultural animal species. Identifying genes associated with disease development has the potential to make selective breeding for disease tolerance more likely to succeed through the selection of different genes in diverse signaling pathways. In this study, four families of Pacific oysters (Crassostrea gigas) were identified to be segregating for a quantitative trait locus (QTL) on chromosome 8. This QTL was previously found to be associated with basal antiviral gene expression and survival to ostreid herpesvirus 1 (OsHV-1) mortality events in Tomales Bay, California. Individuals from these four families were phenotyped and genotyped in an attempt to find candidate genes associated with the QTL on chromosome 8. RESULTS Genome-wide allele frequencies of oysters from each family prior to being planting in Tomales Bay were compared with the allele frequencies of oysters from respective families that survived an OsHV-1 mortality event. Six significant unique QTL were identified in two families in these genome-wide allele frequency studies, all of which were located on chromosome 8. Three QTL were assigned to candidate genes (ABCA1, PIK3R1, and WBP2) that have been previously associated with antiviral innate immunity in vertebrates. CONCLUSION The identification of vertebrate antiviral innate immunity genes as candidate genes involved in molluscan antiviral innate immunity reinforces the similarities between the innate immune systems of these two groups. Causal variant identification in these candidate genes will enable future functional studies of these genes in an effort to better understand their antiviral modes of action.
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Affiliation(s)
- Konstantin Divilov
- Department of Fisheries, Wildlife, and Conservation Sciences, Coastal Oregon Marine Experiment Station, Oregon State University, Hatfield Marine Science Center, Newport, OR, 97365, USA.
| | - Noah Merz
- Department of Fisheries, Wildlife, and Conservation Sciences, Coastal Oregon Marine Experiment Station, Oregon State University, Hatfield Marine Science Center, Newport, OR, 97365, USA
| | - Blaine Schoolfield
- Department of Fisheries, Wildlife, and Conservation Sciences, Coastal Oregon Marine Experiment Station, Oregon State University, Hatfield Marine Science Center, Newport, OR, 97365, USA
| | - Timothy J Green
- Centre for Shellfish Research, Vancouver Island University, Nanaimo, BC, V9R 5S5, Canada
| | - Chris Langdon
- Department of Fisheries, Wildlife, and Conservation Sciences, Coastal Oregon Marine Experiment Station, Oregon State University, Hatfield Marine Science Center, Newport, OR, 97365, USA
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de Kantzow M, Hick PM, Whittington RJ. Immune Priming of Pacific Oysters ( Crassostrea gigas) to Induce Resistance to Ostreid herpesvirus 1: Comparison of Infectious and Inactivated OsHV-1 with Poly I:C. Viruses 2023; 15:1943. [PMID: 37766349 PMCID: PMC10536431 DOI: 10.3390/v15091943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 09/08/2023] [Accepted: 09/13/2023] [Indexed: 09/29/2023] Open
Abstract
Pacific oyster mortality syndrome (POMS), which is caused by Ostreid herpesvirus 1 (OsHV-1), causes economic losses in Pacific oyster (Crassostrea gigas) aquaculture in many countries. Reducing the mortality in disease outbreaks requires changing the host, pathogen and environment interactions to favor the host. Survivors of natural exposure to OsHV-1 are able to survive subsequent outbreaks. This has been replicated under laboratory conditions, suggesting the existence of an immune response. The aim of the present study is to compare the effects of prior exposure to infectious OsHV-1, heat-inactivated OsHV-1 and the chemical anti-viral immune stimulant poly I:C on mortality following exposure to virulent OsHV-1. All treatments were administered by intramuscular injection. Oysters were maintained at 18 °C for 14 days; then, the temperature was increased to 22 °C and the oysters were challenged with virulent OsHV-1. Heat-inactivated OsHV-1, infectious OsHV-1 and poly I:C all induced significant protection against mortality, with the hazard of death being 0.41, 0.18 and 0.02, respectively, compared to the controls, which had no immune priming. The replication of OsHV-1 on first exposure was not required to induce a protective response. While the underlying mechanisms for protection remain to be elucidated, conditioning for resistance to POMS by prior exposure to inactivated or infectious OsHV-1 may have practical applications in oyster farming but requires further development to optimize the dose and delivery mechanism and evaluate the duration of protection.
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Affiliation(s)
| | | | - Richard J. Whittington
- School of Veterinary Science, Faculty of Science, The University of Sydney, 425 Werombi Road, Camden, NSW 2570, Australia
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4
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Trancart S, Tweedie A, Liu O, Paul-Pont I, Hick P, Houssin M, Whittington RJ. Diversity and molecular epidemiology of Ostreid herpesvirus 1 in farmed Crassostrea gigas in Australia: Geographic clusters and implications for "microvariants" in global mortality events. Virus Res 2023; 323:198994. [PMID: 36332723 PMCID: PMC10194400 DOI: 10.1016/j.virusres.2022.198994] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Revised: 10/26/2022] [Accepted: 10/31/2022] [Indexed: 11/08/2022]
Abstract
Since 2010, mass mortality events known as Pacific oyster mortality syndrome (POMS) have occurred in Crassostrea gigas in Australia associated with Ostreid herpesvirus 1. The virus was thought to be an OsHV-1 µVar or "microvariant", i.e. one of the dominant variants associated with POMS in Europe, but there are few data to characterize the genotype in Australia. Consequently, the genetic identity and diversity of the virus was determined to understand the epidemiology of the disease in Australia. Samples were analysed from diseased C. gigas over five summer seasons between 2011 and 2016 in POMS-affected estuaries: Georges River in New South Wales (NSW), Hawkesbury River (NSW) and Pitt Water in Tasmania. Sequencing was attempted for six genomic regions. Numerous variants were identified among these regions (n = 100 isolates) while twelve variants were identified from concatenated nucleotide sequences (n = 61 isolates). Nucleotide diversity of the seven genotypes of C region among Australian isolates (Pi 0.99 × 10-3) was the lowest globally. All Australian isolates grouped in a cluster distinct from other OsHV-1 isolates worldwide. This is the first report that Australian outbreaks of POMS were associated with OsHV-1 distinct from OsHV-1 reference genotype, µVar and other microvariants from other countries. The findings illustrate that microvariants are not the only variants of OsHV-1 associated with mass mortality events in C. gigas. In addition, there was mutually exclusive spatial clustering of viral genomic and amino acid sequence variants between estuaries, and a possible association between genotype/amino acid sequence and the prevalence and severity of POMS, as this differed between these estuaries. The sequencing findings supported prior epidemiological evidence for environmental reservoirs of OsHV-1 for POMS outbreaks in Australia.
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Affiliation(s)
- Suzanne Trancart
- LABÉO Research Department, 1 Route de Rosel, Cedex 4, Caen 14053, France
| | - Alison Tweedie
- The University of Sydney, Sydney School of Veterinary Science, Faculty of Science, 425 Werombi Rd, Camden, NSW 2570, Australia; Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Menangle, NSW 2568, Australia
| | - Olivia Liu
- The University of Sydney, Sydney School of Veterinary Science, Faculty of Science, 425 Werombi Rd, Camden, NSW 2570, Australia; Department of Agriculture, Water and the Environment, Canberra, ACT 2601, Australia
| | - Ika Paul-Pont
- The University of Sydney, Sydney School of Veterinary Science, Faculty of Science, 425 Werombi Rd, Camden, NSW 2570, Australia; LEMAR, Rue Dumont d'Urville, Plouzané 29280, France
| | - Paul Hick
- The University of Sydney, Sydney School of Veterinary Science, Faculty of Science, 425 Werombi Rd, Camden, NSW 2570, Australia; Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Menangle, NSW 2568, Australia
| | - Maryline Houssin
- LABÉO Research Department, 1 Route de Rosel, Cedex 4, Caen 14053, France; UMR BOREA Université de Caen Normandie, MNHN, CNRS 8067, SU, IRD 207, UCN, UA, Esplanade de la Paix Caen Cedex 4 14032, France
| | - Richard J Whittington
- The University of Sydney, Sydney School of Veterinary Science, Faculty of Science, 425 Werombi Rd, Camden, NSW 2570, Australia.
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Delisle L, Laroche O, Hilton Z, Burguin JF, Rolton A, Berry J, Pochon X, Boudry P, Vignier J. Understanding the Dynamic of POMS Infection and the Role of Microbiota Composition in the Survival of Pacific Oysters, Crassostrea gigas. Microbiol Spectr 2022; 10:e0195922. [PMID: 36314927 PMCID: PMC9769987 DOI: 10.1128/spectrum.01959-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 09/16/2022] [Indexed: 11/07/2022] Open
Abstract
For over a decade, Pacific oyster mortality syndrome (POMS), a polymicrobial disease, induced recurring episodes of massive mortality affecting Crassostrea gigas oysters worldwide. Recent studies evidenced a combined infection of the ostreid herpesvirus (OsHV-1 μVar) and opportunistic bacteria in affected oysters. However, the role of the oyster microbiota in POMS is not fully understood. While some bacteria can protect hosts from infection, even minor changes to the microbial communities may also facilitate infection and worsen disease severity. Using a laboratory-based experimental infection model, we challenged juveniles from 10 biparental oyster families with previously established contrasted genetically based ability to survive POMS in the field. Combining molecular analyses and 16S rRNA gene sequencing with histopathological observations, we described the temporal kinetics of POMS and characterized the changes in microbiota during infection. By associating the microbiota composition with oyster mortality rate, viral load, and viral gene expression, we were able to identify both potentially harmful and beneficial bacterial amplicon sequence variants (ASVs). We also observed a delay in viral infection resulting in a later onset of mortality in oysters compared to previous observations and a lack of evidence of fatal dysbiosis in infected oysters. Overall, these results provide new insights into how the oyster microbiome may influence POMS disease outcomes and open new perspectives on the use of microbiome composition as a complementary screening tool to determine shellfish health and potentially predict oyster vulnerability to POMS. IMPORTANCE For more than a decade, Pacific oyster mortality syndrome (POMS) has severely impacted the Crassostrea gigas aquaculture industry, at times killing up to 100% of young farmed Pacific oysters, a key commercial species that is cultivated globally. These disease outbreaks have caused major financial losses for the oyster aquaculture industry. Selective breeding has improved disease resistance in oysters, but some levels of mortality persist, and additional knowledge of the disease progression and pathogenicity is needed to develop complementary mitigation strategies. In this holistic study, we identified some potentially harmful and beneficial bacteria that can influence the outcome of the disease. These results will contribute to advance disease management and aquaculture practices by improving our understanding of the mechanisms behind genetic resistance to POMS and assisting in predicting oyster vulnerability to POMS.
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Affiliation(s)
| | | | | | | | | | | | - Xavier Pochon
- Cawthron Institute, Nelson, New Zealand
- Institute of Marine Science, University of Auckland, Warkworth, New Zealand
| | - Pierre Boudry
- Département Ressources Biologiques et Environnement, Ifremer, ZI de la pointe du diable, Plouzané, France
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6
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Delmotte J, Pelletier C, Morga B, Galinier R, Petton B, Lamy JB, Kaltz O, Avarre JC, Jacquot M, Montagnani C, Escoubas JM. Genetic diversity and connectivity of the Ostreid herpesvirus 1 populations in France: A first attempt to phylogeographic inference for a marine mollusc disease. Virus Evol 2022; 8:veac039. [PMID: 35600094 PMCID: PMC9119428 DOI: 10.1093/ve/veac039] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 04/19/2022] [Accepted: 04/22/2022] [Indexed: 11/18/2022] Open
Abstract
The genetic diversity of viral populations is a key driver of the spatial and temporal diffusion of viruses; yet, studying the diversity of whole genomes from natural populations still remains a challenge. Phylodynamic approaches are commonly used for RNA viruses harboring small genomes but have only rarely been applied to DNA viruses with larger genomes. Here, we used the Pacific oyster mortality syndrome (a disease that affects oyster farms around the world) as a model to study the genetic diversity of its causative agent, the Ostreid herpesvirus 1 (OsHV-1) in the three main French oyster-farming areas. Using ultra-deep sequencing on individual moribund oysters and an innovative combination of bioinformatics tools, we de novo assembled twenty-one OsHV-1 new genomes. Combining quantification of major and minor genetic variations, phylogenetic analysis, and ancestral state reconstruction of discrete traits approaches, we assessed the connectivity of OsHV-1 viral populations between the three oyster-farming areas. Our results suggest that the Marennes-Oléron Bay represents the main source of OsHV-1 diversity, from where the virus has dispersed to other farming areas, a scenario consistent with current practices of oyster transfers in France. We demonstrate that phylodynamic approaches can be applied to aquatic DNA viruses to determine how epidemiological, immunological, and evolutionary processes act and potentially interact to shape their diversity patterns.
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Affiliation(s)
| | - Camille Pelletier
- Ifremer, RBE-ASIM, Station La Tremblade, La Tremblade F-17390, France
| | - Benjamin Morga
- Ifremer, RBE-ASIM, Station La Tremblade, La Tremblade F-17390, France
| | - Richard Galinier
- IHPE, CNRS, Ifremer, UPVD, University of Montpellier, Perpignan F-66000, France
| | - Bruno Petton
- Ifremer, CNRS, IRD, Ifremer, LEMAR UMR 6539 Université de Bretagne Occidentale, Argenton-en-Landunvez F-29840, France
| | | | - Oliver Kaltz
- ISEM, IRD, CNRS, University of Montpellier, Montpellier F-34095, France
| | | | - Maude Jacquot
- Ifremer, RBE-ASIM, Station La Tremblade, La Tremblade F-17390, France
- IHPE, CNRS, Ifremer, UPVD, University of Montpellier, Montpellier F-34095, France
| | - Caroline Montagnani
- IHPE, CNRS, Ifremer, UPVD, University of Montpellier, Montpellier F-34095, France
| | - Jean-Michel Escoubas
- IHPE, CNRS, Ifremer, UPVD, University of Montpellier, Montpellier F-34095, France
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7
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Morga B, Jacquot M, Pelletier C, Chevignon G, Dégremont L, Biétry A, Pepin JF, Heurtebise S, Escoubas JM, Bean TP, Rosani U, Bai CM, Renault T, Lamy JB. Genomic Diversity of the Ostreid Herpesvirus Type 1 Across Time and Location and Among Host Species. Front Microbiol 2021; 12:711377. [PMID: 34326830 PMCID: PMC8313985 DOI: 10.3389/fmicb.2021.711377] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 06/21/2021] [Indexed: 11/15/2022] Open
Abstract
The mechanisms underlying virus emergence are rarely well understood, making the appearance of outbreaks largely unpredictable. This is particularly true for pathogens with low per-site mutation rates, such as DNA viruses, that do not exhibit a large amount of evolutionary change among genetic sequences sampled at different time points. However, whole-genome sequencing can reveal the accumulation of novel genetic variation between samples, promising to render most, if not all, microbial pathogens measurably evolving and suitable for analytical techniques derived from population genetic theory. Here, we aim to assess the measurability of evolution on epidemiological time scales of the Ostreid herpesvirus 1 (OsHV-1), a double stranded DNA virus of which a new variant, OsHV-1 μVar, emerged in France in 2008, spreading across Europe and causing dramatic economic and ecological damage. We performed phylogenetic analyses of heterochronous (n = 21) OsHV-1 genomes sampled worldwide. Results show sufficient temporal signal in the viral sequences to proceed with phylogenetic molecular clock analyses and they indicate that the genetic diversity seen in these OsHV-1 isolates has arisen within the past three decades. OsHV-1 samples from France and New Zealand did not cluster together suggesting a spatial structuration of the viral populations. The genome-wide study of simple and complex polymorphisms shows that specific genomic regions are deleted in several isolates or accumulate a high number of substitutions. These contrasting and non-random patterns of polymorphism suggest that some genomic regions are affected by strong selective pressures. Interestingly, we also found variant genotypes within all infected individuals. Altogether, these results provide baseline evidence that whole genome sequencing could be used to study population dynamic processes of OsHV-1, and more broadly herpesviruses.
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Affiliation(s)
| | | | | | | | | | | | - Jean-François Pepin
- Ifremer, ODE-Littoral-Laboratoire Environnement Ressources des Pertuis Charentais (LER-PC), La Tremblade, France
| | | | - Jean-Michel Escoubas
- IHPE, CNRS, Ifremer, Université de Montpellier - Université de Perpignan Via Domitia, Montpellier, France
| | - Tim P Bean
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, United Kingdom.,Centre for Environment, Fisheries and Aquaculture Science, Weymouth, United Kingdom
| | - Umberto Rosani
- Department of Biology, University of Padua, Padua, Italy
| | - Chang-Ming Bai
- Yellow Sea Fisheries Research Institute, CAFS, Qingdao, China
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8
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Gustafson LL, Arzul I, Burge CA, Carnegie RB, Caceres-Martinez J, Creekmore L, Dewey W, Elston R, Friedman CS, Hick P, Hudson K, Lupo C, Rheault R, Spiegel K, Vásquez-Yeomans R. Optimizing surveillance for early disease detection: Expert guidance for Ostreid herpesvirus surveillance design and system sensitivity calculation. Prev Vet Med 2021; 194:105419. [PMID: 34274864 DOI: 10.1016/j.prevetmed.2021.105419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 06/22/2021] [Accepted: 06/26/2021] [Indexed: 10/21/2022]
Abstract
To keep pace with rising opportunities for disease emergence and spread, surveillance in aquaculture must enable the early detection of both known and new pathogens. Conventional surveillance systems (designed to provide proof of disease freedom) may not support detection outside of periodic sampling windows, leaving substantial blind spots to pathogens that emerge in other times and places. To address this problem, we organized an expert panel to envision optimal systems for early disease detection, focusing on Ostreid herpesvirus 1 (OsHV-1), a pathogen of panzootic consequence to oyster industries. The panel followed an integrative group process to identify and weight surveillance system traits perceived as critical to the early detection of OsHV-1. Results offer a road map with fourteen factors to consider when building surveillance systems geared to early detection; factor weights can be used by planners and analysts to compare the relative value of different designs or enhancements. The results were also used to build a simple, but replicable, model estimating the system sensitivity (SSe) of observational surveillance and, in turn, the confidence in disease freedom that negative reporting can provide. Findings suggest that optimally designed observational systems can contribute substantially to both early detection and disease freedom confidence. In contrast, active surveillance as a singular system is likely insufficient for early detection. The strongest systems combined active with observational surveillance and engaged joint industry and government involvement: results suggest that effective partnerships can generate highly sensitive systems, whereas ineffective partnerships may seriously erode early detection capability. Given the costs of routine testing, and the value (via averted losses) of early detection, we conclude that observational surveillance is an important and potentially very effective tool for health management and disease prevention on oyster farms, but one that demands careful planning and participation. This evaluation centered on OsHV-1 detection in farmed oyster populations. However, many of the features likely generalize to other pathogens and settings, with the important caveat that the pathogens need to manifest via morbidity or mortality events in the species, life stages and environments under observation.
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Affiliation(s)
- Lori L Gustafson
- Animal and Plant Health Inspection Services, U.S. Department of Agriculture, 2150 Centre Ave, Fort Collins, CO, 80526, USA.
| | - Isabelle Arzul
- Laboratoire de Genetique et Pathologie des Mollusques Marins, Ifremer, SG2M-LGPMM, Avenue de Mus de Loup, La Tremblade, 17390, France
| | - Colleen A Burge
- Institute of Marine and Environmental Technology, University of Maryland Baltimore County, 701 E Pratt Street, Baltimore, MD, 21202, USA
| | - Ryan B Carnegie
- Virginia Institute of Marine Science, William & Mary, P.O. Box 1346, Gloucester Point, VA, 23062, USA
| | - Jorge Caceres-Martinez
- Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Carretera Ensenada-Tijuana No. 3918, Zona Playitas, Ensenada, Baja California, 22860, Mexico
| | - Lynn Creekmore
- Animal and Plant Health Inspection Services, U.S. Department of Agriculture, 2150 Centre Ave, Fort Collins, CO, 80526, USA
| | - William Dewey
- Taylor Shellfish Farms, 130 SE Lynch Rd., Shelton, WA, 98584, USA
| | - Ralph Elston
- AquaTechnics Inc. PO Box 687, Carlsborg, WA, 98324, USA
| | - Carolyn S Friedman
- School of Aquatic and Fishery Sciences, University of Washington, Box 355020, Seattle, WA, 98195, USA
| | - Paul Hick
- Sydney School of Veterinary Science, 425 Werombi Road, Camden, New South Wales, 2570, Australia
| | - Karen Hudson
- Virginia Institute of Marine Science, William & Mary, P.O. Box 1346, Gloucester Point, VA, 23062, USA
| | - Coralie Lupo
- Laboratoire de Genetique et Pathologie des Mollusques Marins, Ifremer, SG2M-LGPMM, Avenue de Mus de Loup, La Tremblade, 17390, France
| | - Robert Rheault
- East Coast Shellfish Growers Association, 1121 Mooresfield Rd., Wakefield, RI, 02879, USA
| | - Kevin Spiegel
- Animal and Plant Health Inspection Services, U.S. Department of Agriculture, 2150 Centre Ave, Fort Collins, CO, 80526, USA
| | - Rebeca Vásquez-Yeomans
- Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Carretera Ensenada-Tijuana No. 3918, Zona Playitas, Ensenada, Baja California, 22860, Mexico
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9
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Burge CA, Friedman CS, Kachmar ML, Humphrey KL, Moore JD, Elston RA. The first detection of a novel OsHV-1 microvariant in San Diego, California, USA. J Invertebr Pathol 2021; 184:107636. [PMID: 34116033 DOI: 10.1016/j.jip.2021.107636] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 01/25/2021] [Accepted: 06/04/2021] [Indexed: 11/15/2022]
Abstract
The spread, emergence, and adaptation of pathogens causing marine disease has been problematic to fisheries and aquaculture industries for the last several decades creating the need for strategic management and biosecurity practices. The Pacific oyster (Crassostrea gigas), a highly productive species globally, has been a target of disease and mortality caused by a viral pathogen, the Ostreid herpesvirus 1 (OsHV-1) and its microvariants (OsHV-1 µvars). During routine surveillance to establish health history at a shellfish aquaculture nursery system in San Diego, California, the presence of OsHV-1 in Pacific oyster juveniles was detected. Quantification of OsHV-1 in tissues of oysters revealed OsHV-1 viral loads > 106 copies/mg. We characterized and identified the OsHV-1 variant by sequencing of ORFs 4 (C2/C6) and 43 (IA1/IA2), which demonstrated that this variant is a novel OsHV-1 microvariant: OsHV-1 µvar SD. A pilot transmission study indicates that OsHV-1 µvar SD is infectious with high viral loads ~ 7.57 × 106 copies/mg detected in dead individuals. The detection of OsHV-1 µvar SD in a large port mirrors previous studies conducted in Australia where aquaculture farms and feral populations near port locations may be at a higher risk of OsHV-1 emergence. Further research is needed to understand the impacts of OsHV-1 µvar SD, such as transmission studies focusing on potential vectors and characterization of virulence as compared to other OsHV-1 µvars. To increase biosecurity of the global aquaculture industry, active and passive surveillance may be necessary to reduce spread of pathogens and make appropriate management decisions.
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Affiliation(s)
- Colleen A Burge
- Institute of Marine & Environmental Technology, University of Maryland Baltimore County, 701 E Pratt Street, Baltimore, MD 21202, USA.
| | - Carolyn S Friedman
- School of Aquatic & Fishery Sciences, University of Washington, Box 355020, Seattle, WA 98105, USA
| | - Mariah L Kachmar
- Institute of Marine & Environmental Technology, University of Maryland Baltimore County, 701 E Pratt Street, Baltimore, MD 21202, USA
| | | | - James D Moore
- California Department of Fish & Wildlife, UC Davis Bodega Marine Laboratory, 2099 Westside Road, Bodega Bay, CA 94923, USA
| | - Ralph A Elston
- AquaTechnics Inc, 455 West Bell Street, Sequim, WA 98382, USA
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10
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Reduction in Virulence over Time in Ostreid herpesvirus 1 (OsHV-1) Microvariants between 2011 and 2015 in Australia. Viruses 2021; 13:v13050946. [PMID: 34065570 PMCID: PMC8160646 DOI: 10.3390/v13050946] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/06/2021] [Accepted: 05/17/2021] [Indexed: 01/05/2023] Open
Abstract
Microvariant genotypes of Ostreid herpesvirus 1 (OsHV-1) are associated with mass mortality events of Pacific oysters in many countries. The OsHV-1 microvariant (µVar) emerged in France 2008 and caused significant economic losses as it became endemic and displaced the previously dominant OsHV-1 reference genotype. Recently, considerable genotypic variation has been described for OsHV-1 microvariants, however, less is known about variation in viral phenotype. This study used an in vivo laboratory infection model to assess differences in total cumulative mortality, peak viral load, transmissibility, and dose-response for three OsHV-1 isolates obtained between 2011 and 2015 from endemic waterways in Australia. This followed field observations of apparent reductions in the severity of mass mortalities over this time. Significantly higher hazard of death and cumulative mortality were observed for an isolate obtained in 2011 compared to isolates from 2014–2015. In keeping with other studies, the hazard of death was higher in oysters challenged by injection compared to challenge by cohabitation and the mortality was higher when the initial dose was 1 × 104 OsHV-1 DNA copies per oyster injection compared to 1 × 102 DNA copies. There was no difference in the quantity of OsHV-1 DNA at time of death that could be related to isolate or dose, suggesting similar pathogenetic processes in the individual oysters that succumbed to end-stage disease. While the isolates examined in this study were biased towards pathogenic types of OsHV-1, as they were collected during disease outbreaks, the variation in virulence that was observed, when combined with prior data on subclinical infections, suggests that surveillance for low virulence genotypes of OsHV-1 would be rewarding. This may lead to new approaches to disease management which utilize controlled exposure to attenuated strains of OsHV-1.
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Whittington RJ, Hick P, Fuhrmann M, Liu O, Paul-Pont I. Removal of oyster pathogens from seawater. ENVIRONMENT INTERNATIONAL 2021; 150:106258. [PMID: 33243468 DOI: 10.1016/j.envint.2020.106258] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/30/2020] [Accepted: 10/31/2020] [Indexed: 06/11/2023]
Affiliation(s)
- R J Whittington
- School of Veterinary Science, The University of Sydney, Camden, NSW 2570, Australia.
| | - P Hick
- School of Veterinary Science, The University of Sydney, Camden, NSW 2570, Australia
| | - M Fuhrmann
- School of Veterinary Science, The University of Sydney, Camden, NSW 2570, Australia
| | - O Liu
- School of Veterinary Science, The University of Sydney, Camden, NSW 2570, Australia; Aquatic Pest and Health Policy, Animal Health Policy Branch, Biosecurity Animal Division, Australian Government Department of Agriculture, Water and the Environment, Canberra, ACT 2601, Australia(1)
| | - I Paul-Pont
- School of Veterinary Science, The University of Sydney, Camden, NSW 2570, Australia; Laboratoire des Sciences de l'Environnement Marin (LEMAR), CNRS/UBO/IRD/IFREMER Institut Universitaire Europeen de la Mer, 29280 Plouzane, France(1)
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Petton B, Destoumieux-Garzón D, Pernet F, Toulza E, de Lorgeril J, Degremont L, Mitta G. The Pacific Oyster Mortality Syndrome, a Polymicrobial and Multifactorial Disease: State of Knowledge and Future Directions. Front Immunol 2021; 12:630343. [PMID: 33679773 PMCID: PMC7930376 DOI: 10.3389/fimmu.2021.630343] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 01/06/2021] [Indexed: 01/22/2023] Open
Abstract
The Pacific oyster (Crassostreae gigas) has been introduced from Asia to numerous countries around the world during the 20th century. C. gigas is the main oyster species farmed worldwide and represents more than 98% of oyster production. The severity of disease outbreaks that affect C. gigas, which primarily impact juvenile oysters, has increased dramatically since 2008. The most prevalent disease, Pacific oyster mortality syndrome (POMS), has become panzootic and represents a threat to the oyster industry. Recently, major steps towards understanding POMS have been achieved through integrative molecular approaches. These studies demonstrated that infection by Ostreid herpesvirus type 1 µVar (OsHV-1 µvar) is the first critical step in the infectious process and leads to an immunocompromised state by altering hemocyte physiology. This is followed by dysbiosis of the microbiota, which leads to a secondary colonization by opportunistic bacterial pathogens, which in turn results in oyster death. Host and environmental factors (e.g. oyster genetics and age, temperature, food availability, and microbiota) have been shown to influence POMS permissiveness. However, we still do not understand the mechanisms by which these different factors control disease expression. The present review discusses current knowledge of this polymicrobial and multifactorial disease process and explores the research avenues that must be investigated to fully elucidate the complexity of POMS. These discoveries will help in decision-making and will facilitate the development of tools and applied innovations for the sustainable and integrated management of oyster aquaculture.
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Affiliation(s)
- Bruno Petton
- Ifremer, LEMAR UMR 6539, UBO/CNRS/IRD/Ifremer, Argenton-en-Landunvez, France
| | | | - Fabrice Pernet
- Ifremer, LEMAR UMR 6539, UBO/CNRS/IRD/Ifremer, Argenton-en-Landunvez, France
| | - Eve Toulza
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Montpellier, France
| | - Julien de Lorgeril
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Montpellier, France
| | | | - Guillaume Mitta
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Montpellier, France
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13
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Prado-Alvarez M, García-Fernández P, Faury N, Azevedo C, Morga B, Gestal C. First detection of OsHV-1 in the cephalopod Octopus vulgaris. Is the octopus a dead-end for OsHV-1? J Invertebr Pathol 2021; 183:107553. [PMID: 33596434 DOI: 10.1016/j.jip.2021.107553] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 01/28/2021] [Accepted: 02/09/2021] [Indexed: 11/29/2022]
Abstract
The ostreid herpes virus (OsHV-1), associated with massive mortalities in the bivalve Crassostrea gigas, was detected for the first time in the cephalopod Octopus vulgaris. Wild adult animals from a natural breeding area in Spain showed an overall prevalence of detection of 87.5% between 2010 and 2015 suggesting an environmental source of viral material uptake. Overall positive PCR detections were significantly higher in adult animals (p = 0.031) compared to newly hatched paralarvae (62%). Prevalence in embryos reached 65%. Sequencing of positive amplicons revealed a match with the variant OsHV-1 µVar showing the genomic features that distinguish this variant in the ORF4. Gill tissues from adult animals were also processed for in situ hybridization and revealed positive labelling. Experimental exposure trials in octopus paralarvae were carried out by cohabitation with virus injected oysters and by immersion in viral suspension observing a significant decrease in paralarval survival in both experiments. An increase in the number of OsHV-1 positive animals was detected in dead paralarvae after cohabitation with virus injected oysters. No signs of viral replication were observed based on lack of viral gene expression or visualization of viral structures by transmission electron microscopy. The octopus response against OsHV-1 was evaluated by gene expression of previously reported transcripts involved in immune response in C. gigas suggesting that immune defences in octopus are also activated after exposure to OsHV-1.
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Affiliation(s)
- Maria Prado-Alvarez
- Marine Molecular Pathobiology Group, Marine Research Institute, Spanish National Research Council, Eduardo Cabello 6, 36208 Vigo, Spain.
| | - Pablo García-Fernández
- Marine Molecular Pathobiology Group, Marine Research Institute, Spanish National Research Council, Eduardo Cabello 6, 36208 Vigo, Spain
| | - Nicole Faury
- IFREMER, Laboratoire de Génétique et Pathologie des Mollusques Marins, Avenue de Mus de Loup, 17390 La Tremblade, France
| | - Carlos Azevedo
- Interdisciplinary Center of Marine and Environmental Research, University of Porto, Rua dos Bragas 289, 4050-123 Porto, Portugal; Institute of Biomedical Sciences Abel Salazar, University of Porto, Rua Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal
| | - Benjamin Morga
- IFREMER, Laboratoire de Génétique et Pathologie des Mollusques Marins, Avenue de Mus de Loup, 17390 La Tremblade, France
| | - Camino Gestal
- Marine Molecular Pathobiology Group, Marine Research Institute, Spanish National Research Council, Eduardo Cabello 6, 36208 Vigo, Spain.
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Leprêtre M, Faury N, Segarra A, Claverol S, Degremont L, Palos-Ladeiro M, Armengaud J, Renault T, Morga B. Comparative Proteomics of Ostreid Herpesvirus 1 and Pacific Oyster Interactions With Two Families Exhibiting Contrasted Susceptibility to Viral Infection. Front Immunol 2021; 11:621994. [PMID: 33537036 PMCID: PMC7848083 DOI: 10.3389/fimmu.2020.621994] [Citation(s) in RCA: 6] [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: 10/27/2020] [Accepted: 11/30/2020] [Indexed: 12/13/2022] Open
Abstract
Massive mortality outbreaks affecting Pacific oysters (Crassostrea gigas) spat/juveniles are often associated with the detection of a herpesvirus called ostreid herpesvirus type 1 (OsHV-1). In this work, experimental infection trials of C. gigas spat with OsHV-1 were conducted using two contrasted Pacific oyster families for their susceptibility to viral infection. Live oysters were sampled at 12, 26, and 144 h post infection (hpi) to analyze host-pathogen interactions using comparative proteomics. Shotgun proteomics allowed the detection of seven viral proteins in infected oysters, some of them with potential immunomodulatoy functions. Viral proteins were mainly detected in susceptible oysters sampled at 26 hpi, which correlates with the mortality and viral load observed in this oyster family. Concerning the Pacific oyster proteome, more than 3,000 proteins were identified and contrasted proteomic responses were observed between infected A- and P-oysters, sampled at different post-injection times. Gene ontology (GO) and KEGG pathway enrichment analysis performed on significantly modulated proteins uncover the main immune processes (such as RNA interference, interferon-like pathway, antioxidant defense) which contribute to the defense and resistance of Pacific oysters to viral infection. In the more susceptible Pacific oysters, results suggest that OsHV-1 manipulate the molecular machinery of host immune response, in particular the autophagy system. This immunomodulation may lead to weakening and consecutively triggering death of Pacific oysters. The identification of several highly modulated and defense-related Pacific oyster proteins from the most resistant oysters supports the crucial role played by the innate immune system against OsHV-1 and the viral infection. Our results confirm the implication of proteins involved in an interferon-like pathway for efficient antiviral defenses and suggest that proteins involved in RNA interference process prevent viral replication in C. gigas. Overall, this study shows the interest of multi-omic approaches applied on groups of animals with differing sensitivities and provides novel insight into the interaction between Pacific oyster and OsHV-1 with key proteins involved in viral infection resistance.
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Affiliation(s)
- Maxime Leprêtre
- Université de Reims Champagne-Ardenne, UMR-I 02 INERIS-URCA-ULH SEBIO Unité Stress Environnementaux et BIOsurveillance des milieux aquatiques, UFR Sciences Exactes et Naturelles, Campus du Moulin de la Housse, Reims, France
| | - Nicole Faury
- SG2M-LGPMM, Laboratoire De Génétique Et Pathologie Des Mollusques Marins, Ifremer, La Tremblade, France
| | - Amélie Segarra
- Department of Anatomy, Physiology & Cell Biology, School of Veterinary Medicine, University of California, Davis, CA, United States
| | - Stéphane Claverol
- Centre Génomique Fonctionnelle de Bordeaux, Plateforme Protéome, Université de Bordeaux, Bordeaux, France
| | - Lionel Degremont
- SG2M-LGPMM, Laboratoire De Génétique Et Pathologie Des Mollusques Marins, Ifremer, La Tremblade, France
| | - Mélissa Palos-Ladeiro
- Université de Reims Champagne-Ardenne, UMR-I 02 INERIS-URCA-ULH SEBIO Unité Stress Environnementaux et BIOsurveillance des milieux aquatiques, UFR Sciences Exactes et Naturelles, Campus du Moulin de la Housse, Reims, France
| | - Jean Armengaud
- Université Paris-Saclay, CEA, INRAE, DépartementMédicaments et Technologies pour la Santé (DMTS), SPI, Bagnols-sur-Cèze, France
| | - Tristan Renault
- Département Ressources Biologiques Et Environnement, Ifremer, Nantes, France
| | - Benjamin Morga
- SG2M-LGPMM, Laboratoire De Génétique Et Pathologie Des Mollusques Marins, Ifremer, La Tremblade, France
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15
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Lassudrie M, Hégaret H, Wikfors GH, da Silva PM. Effects of marine harmful algal blooms on bivalve cellular immunity and infectious diseases: A review. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2020; 108:103660. [PMID: 32145294 DOI: 10.1016/j.dci.2020.103660] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 02/04/2020] [Accepted: 02/18/2020] [Indexed: 06/10/2023]
Abstract
Bivalves were long thought to be "symptomless carriers" of marine microalgal toxins to human seafood consumers. In the past three decades, science has come to recognize that harmful algae and their toxins can be harmful to grazers, including bivalves. Indeed, studies have shown conclusively that some microalgal toxins function as active grazing deterrents. When responding to marine Harmful Algal Bloom (HAB) events, bivalves can reject toxic cells to minimize toxin and bioactive extracellular compound (BEC) exposure, or ingest and digest cells, incorporating nutritional components and toxins. Several studies have reported modulation of bivalve hemocyte variables in response to HAB exposure. Hemocytes are specialized cells involved in many functions in bivalves, particularly in immunological defense mechanisms. Hemocytes protect tissues by engulfing or encapsulating living pathogens and repair tissue damage caused by injury, poisoning, and infections through inflammatory processes. The effects of HAB exposure observed on bivalve cellular immune variables have raised the question of possible effects on susceptibility to infectious disease. As science has described a previously unrecognized diversity in microalgal bioactive substances, and also found a growing list of infectious diseases in bivalves, episodic reports of interactions between harmful algae and disease in bivalves have been published. Only recently, studies directed to understand the physiological and metabolic bases of these interactions have been undertaken. This review compiles evidence from studies of harmful algal effects upon bivalve shellfish that establishes a framework for recent efforts to understand how harmful algae can alter infectious disease, and particularly the fundamental role of cellular immunity, in modulating these interactions. Experimental studies reviewed here indicate that HABs can modulate bivalve-pathogen interactions in various ways, either by increasing bivalve susceptibility to disease or conversely by lessening infection proliferation or transmission. Alteration of immune defense and global physiological distress caused by HAB exposure have been the most frequent reasons identified for these effects on disease. Only few studies, however, have addressed these effects so far and a general pattern cannot be established. Other mechanisms are likely involved but are under-studied thus far and will need more attention in the future. In particular, the inhibition of bivalve filtration by HABs and direct interaction between HABs and infectious agents in the seawater likely interfere with pathogen transmission. The study of these interactions in the field and at the population level also are needed to establish the ecological and economical significance of the effects of HABs upon bivalve diseases. A more thorough understanding of these interactions will assist in development of more effective management of bivalve shellfisheries and aquaculture in oceans subjected to increasing HAB and disease pressures.
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Affiliation(s)
| | - Hélène Hégaret
- CNRS, Univ Brest, IRD, Ifremer, LEMAR, F-29280, Plouzané, France
| | - Gary H Wikfors
- NOAA Fisheries Service, Northeast Fisheries Science Center, Milford, CT, 0640, USA
| | - Patricia Mirella da Silva
- Laboratory of Immunology and Pathology of Invertebrates, Department of Molecular Biology, Federal University of Paraíba (UFPB), Paraíba, Brazil
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16
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Dupont S, Lokmer A, Corre E, Auguet JC, Petton B, Toulza E, Montagnani C, Tanguy G, Pecqueur D, Salmeron C, Guillou L, Desnues C, La Scola B, Bou Khalil J, de Lorgeril J, Mitta G, Gueguen Y, Escoubas JM. Oyster hemolymph is a complex and dynamic ecosystem hosting bacteria, protists and viruses. Anim Microbiome 2020; 2:12. [PMID: 33499958 PMCID: PMC7807429 DOI: 10.1186/s42523-020-00032-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 04/14/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND The impact of the microbiota on host fitness has so far mainly been demonstrated for the bacterial microbiome. We know much less about host-associated protist and viral communities, largely due to technical issues. However, all microorganisms within a microbiome potentially interact with each other as well as with the host and the environment, therefore likely affecting the host health. RESULTS We set out to explore how environmental and host factors shape the composition and diversity of bacterial, protist and viral microbial communities in the Pacific oyster hemolymph, both in health and disease. To do so, five oyster families differing in susceptibility to the Pacific oyster mortality syndrome were reared in hatchery and transplanted into a natural environment either before or during a disease outbreak. Using metabarcoding and shotgun metagenomics, we demonstrate that hemolymph can be considered as an ecological niche hosting bacterial, protist and viral communities, each of them shaped by different factors and distinct from the corresponding communities in the surrounding seawater. Overall, we found that hemolymph microbiota is more strongly shaped by the environment than by host genetic background. Co-occurrence network analyses suggest a disruption of the microbial network after transplantation into natural environment during both non-infectious and infectious periods. Whereas we could not identify a common microbial community signature for healthy animals, OsHV-1 μVar virus dominated the hemolymph virome during the disease outbreak, without significant modifications of other microbiota components. CONCLUSION Our study shows that oyster hemolymph is a complex ecosystem containing diverse bacteria, protists and viruses, whose composition and dynamics are primarily determined by the environment. However, all of these are also shaped by oyster genetic backgrounds, indicating they indeed interact with the oyster host and are therefore not only of transient character. Although it seems that the three microbiome components respond independently to environmental conditions, better characterization of hemolymph-associated viruses could change this picture.
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Affiliation(s)
- S Dupont
- IHPE, Univ. Montpellier, CNRS, Ifremer, Univ. Montpellier, Univ. Perpignan Via Domitia, 34095, Montpellier, France
| | - A Lokmer
- Coastal Ecology, Wadden Sea Station Sylt, Alfred Wegener Institute - Helmholtz Centre for Polar and Marine Research, List auf Sylt, Germany.,Current affiliation UMR 7206 Eco-anthropologie et Ethnologie, CNRS - MNHN Univ. Paris Diderot Sorbonne Paris Cité, Paris, France
| | - E Corre
- Sorbonne Université, CNRS, FR2424 ABiMS (Analysis and Bioanalysis for Marine Sciences), Station Biologique de Roscoff SBR, 29680, Roscoff, France
| | - J-C Auguet
- MARBEC, Université Montpellier, CNRS, IFREMER, IRD, CC093, place Eugène Bataillon, 34095, Montpellier, France
| | - B Petton
- Ifremer, LEMAR UMR 6539, 11 presqu'île du Vivier, 29840, Argenton-en-Landunvez, France
| | - E Toulza
- IHPE, Univ. Montpellier, CNRS, Ifremer, Univ. Montpellier, Univ. Perpignan Via Domitia, 34095, Montpellier, France
| | - C Montagnani
- IHPE, Univ. Montpellier, CNRS, Ifremer, Univ. Montpellier, Univ. Perpignan Via Domitia, 34095, Montpellier, France
| | - G Tanguy
- Sorbonne Université, CNRS, FR2424, Genomer, Station Biologique de Roscoff SBR, 29680, Roscoff, France
| | - D Pecqueur
- Observatoire Océanologique de Banyuls sur Mer, FR 3724, BioPIC, CNRS/SU, Avenue Pierre Fabre, 66650, Banyuls-sur-Mer, France
| | - C Salmeron
- Observatoire Océanologique de Banyuls sur Mer, FR 3724, BioPIC, CNRS/SU, Avenue Pierre Fabre, 66650, Banyuls-sur-Mer, France
| | - L Guillou
- Sorbonne Université, CNRS, UMR7144 Adaptation et Diversité en Milieu Marin, Ecology of Marine Plankton (ECOMAP), Station Biologique de Roscoff SBR, 29680, Roscoff, France
| | - C Desnues
- Aix-Marseille Université, IRD 257, Assistance-Publique des Hôpitaux de Marseille, UMR Microbes, Evolution, Phylogeny and Infections (MEPHI), IHU Méditerranée Infection, 13005, Marseille, France.,Aix-Marseille Université, Université de Toulon, CNRS, IRD, Mediterranean Institute of Oceanography, UM 110, 13288, Marseille, France
| | - B La Scola
- Microbes, Evolution, Phylogeny and Infection (MEΦI), Aix-Marseille Université UM63, Institut de Recherche pour le Développement IRD 198, Assistance Publique - Hôpitaux de Marseille (AP-HM), Marseille, France.,Institut Hospitalo-Universitaire (IHU) - Méditerranée Infection, Marseille, France
| | - J Bou Khalil
- Institut Hospitalo-Universitaire (IHU) - Méditerranée Infection, Marseille, France
| | - J de Lorgeril
- IHPE, Univ. Montpellier, CNRS, Ifremer, Univ. Montpellier, Univ. Perpignan Via Domitia, 34095, Montpellier, France
| | - G Mitta
- IHPE, Univ. Montpellier, CNRS, Ifremer, Univ. Montpellier, Univ. Perpignan Via Domitia, 34095, Montpellier, France
| | - Y Gueguen
- IHPE, Univ. Montpellier, CNRS, Ifremer, Univ. Montpellier, Univ. Perpignan Via Domitia, 34095, Montpellier, France
| | - J-M Escoubas
- IHPE, Univ. Montpellier, CNRS, Ifremer, Univ. Montpellier, Univ. Perpignan Via Domitia, 34095, Montpellier, France.
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Liu O, Paul-Pont I, Rubio A, Dhand N, Whittington RJ. Detection of ostreid herpesvirus-1 in plankton and seawater samples at an estuary scale. DISEASES OF AQUATIC ORGANISMS 2020; 138:1-15. [PMID: 32132267 DOI: 10.3354/dao03445] [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] [Indexed: 06/10/2023]
Abstract
Ostreid herpesvirus-1 (OsHV-1) is known to associate with particles in seawater, leading to infection and disease in the Pacific oyster Crassostrea gigas. The estuarine environment is highly complex and changeable, and this needs to be considered when collecting environmental samples for pathogen detection. The aims of this study were to (1) compare different aspects of collecting natural seawater and plankton samples for detection of OsHV-1 DNA and (2) determine whether detection of OsHV-1 DNA in such environmental samples has merit for disease risk prediction. The results of one experiment suggest that sampling on the outgoing tide may improve the detection of OsHV-1 DNA in seawater and plankton tow samples (odds ratio 2.71). This statistical comparison was not possible in 2 other experiments. The method (plankton tow or beta bottle) and depth of collection (range: 250-1250 mm) had no effect on the likelihood of detection of OsHV-1. OsHV-1 DNA was found at low concentrations in plankton tow and seawater samples, and only when outbreaks of mortality associated with OsHV-1 were observed in nearby experimental or farmed populations of C. gigas. This suggests that single point in time environmental samples of seawater or plankton are not sufficient to rule out the presence of OsHV-1 in an estuary. The association of OsHV-1 with particles in seawater needs to be better understood in order to determine whether more selective and sensitive methods can be devised to detect it, before environmental samples can be reliably used in disease risk prediction.
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Affiliation(s)
- Olivia Liu
- School of Veterinary Science, Faculty of Science, The University of Sydney, Camden, NSW 2570, Australia
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Different in vivo growth of ostreid herpesvirus 1 at 18 °C and 22 °C alters mortality of Pacific oysters (Crassostrea gigas). Arch Virol 2019; 164:3035-3043. [PMID: 31602543 DOI: 10.1007/s00705-019-04427-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 09/09/2019] [Indexed: 01/29/2023]
Abstract
Seasonally recurrent outbreaks of mass mortality in Pacific oysters (Crassostrea gigas) caused by microvariant genotypes of ostreid herpesvirus 1 (OsHV-1) occur in Europe, New Zealand and Australia. The incubation period for OsHV-1 under experimental conditions is 48-72 hours and depends on water temperature, as does the mortality. An in vivo growth curve for OsHV-1 was determined by quantifying OsHV-1 DNA at 10 time points between 2 and 72 hours after exposure to OsHV-1. The peak replication rate was the same at 18 °C and 22 °C; however, there was a longer period of amplification leading to a higher peak concentration at 22 °C (2.34 × 107 copies/mg at 18 hours) compared to 18 °C (1.38 × 105 copies/mg at 12 hours). The peak viral concentration preceded mortality by 72 hours and 20 hours at 18 °C and 22 °C, respectively. Cumulative mortality to day 14 was 45.9% at 22 °C compared to 0.3% at 18 °C. The prevalence of OsHV-1 infection after 14 days at 18 °C was 33.3%. No mortality from OsHV-1 occurred when the water temperature in tanks of oysters challenged at 18 °C was increased to 22 °C for 14 days. The influence of water temperature prior to exposure to OsHV-1 and during the initial virus replication is an important determinant of the outcome of infection in C. gigas.
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Barbieri ES, Medina CD, Vázquez N, Fiorito C, Martelli A, Wigdorovitz A, Schwindt E, Morga B, Renault T, Parreño V, Barón PJ. First detection of Ostreid herpesvirus 1 in wild Crassostrea gigas in Argentina. J Invertebr Pathol 2019; 166:107222. [DOI: 10.1016/j.jip.2019.107222] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 07/23/2019] [Accepted: 07/25/2019] [Indexed: 10/26/2022]
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Martenot C, Faury N, Morga B, Degremont L, Lamy JB, Houssin M, Renault T. Exploring First Interactions Between Ostreid Herpesvirus 1 (OsHV-1) and Its Host, Crassostrea gigas: Effects of Specific Antiviral Antibodies and Dextran Sulfate. Front Microbiol 2019; 10:1128. [PMID: 31178841 PMCID: PMC6543491 DOI: 10.3389/fmicb.2019.01128] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 05/03/2019] [Indexed: 12/18/2022] Open
Abstract
Viral entry mechanisms of herpesviruses constitute a highly complex process which implicates several viral glycoproteins and different receptors on the host cell surfaces. This initial infection stage was currently undescribed for Ostreid herpes virus 1 (OsHV-1), a herpesvirus infecting bivalves including the Pacific oyster, Crassostrea gigas. To identify OsHV-1 glyproteins implicated in the attachment of the virus to oyster cells, three viral putative membrane proteins, encoded by ORF 25, 41, and 72, were selected and polyclonal antibodies against these targets were used to explore first interactions between the virus and host cells. In addition, effects of dextran sulfate, a negative charged sulfated polysaccharide, were investigated on OsHV-1 infection. Effects of antiviral antibodies and dextran sulfate were evaluated by combining viral DNA and RNA detection in spat (in vivo trials) and in oyster hemolymph (in vitro trials). Results showed that viral protein encoded by ORF 25 appeared to be involved in interaction between OsHV-1 and host cells even if other proteins are likely implicated, such as proteins encoded by ORF 72 and ORF 41. Dextran sulfate at 30 μg/mL significantly reduced the spat mortality rate in the experimental conditions. Taken together, these results contribute to better understanding the pathogenesis of the viral infection, especially during the first stage of OsHV-1 infection, and open the way toward new approaches to control OsHV-1 infection in confined facilities.
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Affiliation(s)
- Claire Martenot
- Institut Français de Recherche pour l'Exploitation de la Mer, Laboratoire de Génétique et Pathologie des Mollusques Marins, La Tremblade, France
| | - Nicole Faury
- Institut Français de Recherche pour l'Exploitation de la Mer, Laboratoire de Génétique et Pathologie des Mollusques Marins, La Tremblade, France
| | - Benjamin Morga
- Institut Français de Recherche pour l'Exploitation de la Mer, Laboratoire de Génétique et Pathologie des Mollusques Marins, La Tremblade, France
| | - Lionel Degremont
- Institut Français de Recherche pour l'Exploitation de la Mer, Laboratoire de Génétique et Pathologie des Mollusques Marins, La Tremblade, France
| | - Jean-Baptiste Lamy
- Institut Français de Recherche pour l'Exploitation de la Mer, Laboratoire de Génétique et Pathologie des Mollusques Marins, La Tremblade, France
| | | | - Tristan Renault
- Département Ressources Biologiques et Environnement, Institut Français de Recherche pour l'Exploitation de la Mer, Nantes, France
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21
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de Lorgeril J, Escoubas JM, Loubiere V, Pernet F, Le Gall P, Vergnes A, Aujoulat F, Jeannot JL, Jumas-Bilak E, Got P, Gueguen Y, Destoumieux-Garzón D, Bachère E. Inefficient immune response is associated with microbial permissiveness in juvenile oysters affected by mass mortalities on field. FISH & SHELLFISH IMMUNOLOGY 2018; 77:156-163. [PMID: 29567138 DOI: 10.1016/j.fsi.2018.03.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 03/09/2018] [Accepted: 03/17/2018] [Indexed: 06/08/2023]
Abstract
Since 2008, juvenile Crassostrea gigas oysters have suffered from massive mortalities in European farming areas. This disease of complex etiology is still incompletely understood. Triggered by an elevated seawater temperature, it has been associated to infections by a herpes virus named OsHV-1 as well as pathogenic vibrios of the Splendidus clade. Ruling out the complexity of the disease, most of our current knowledge has been acquired in controlled experiments. Among the many unsolved questions, it is still ignored what role immunity plays in the capacity oysters have to survive an infectious episode. Here we show that juvenile oysters susceptible to the disease mount an inefficient immune response associated with microbial permissiveness and death. We found that, in contrast to resistant adult oysters having survived an earlier episode of mortality, susceptible juvenile oysters never exposed to infectious episodes died by more than 90% in a field experiment. Susceptible oysters were heavily colonized by OsHV-1 herpes virus as well as bacteria including vibrios potentially pathogenic for oysters, which proliferated in oyster flesh and body fluids during the mortality event. Nonetheless, susceptible oysters were found to sense microbes as indicated by an overexpression of immune receptors and immune signaling pathways. However, they did not express important immune effectors involved in antimicrobial immunity and apoptosis and showed repressed expression of genes involved in ROS and metal homeostasis. This contrasted with resistant oysters, which expressed those important effectors, controlled bacterial and viral colonization and showed 100% survival to the mortality event. Altogether, our results demonstrate that the immune response mounted by susceptible oysters lacks some important immune functions and fails in controlling microbial proliferation. This study opens the way to more holistic studies on the "mass mortality syndrome", which are now required to decipher the sequence of events leading to oyster mortalities and determine the relative weight of pathogens, oyster genetics and oyster-associated microbiota in the disease.
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Affiliation(s)
- Julien de Lorgeril
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan, Via Domitia, France.
| | - Jean-Michel Escoubas
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan, Via Domitia, France
| | - Vincent Loubiere
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan, Via Domitia, France
| | - Fabrice Pernet
- Ifremer, LEMAR UMR6539, CNRS/UBO/IRD/Ifremer, F-29280, Plouzané, France
| | - Patrik Le Gall
- MARBEC UMR 9190 (CNRS-IRD-Ifremer-UM), F34203, Sète, France
| | - Agnès Vergnes
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan, Via Domitia, France
| | - Fabien Aujoulat
- UMR 5569 HydroSciences Montpellier, Equipe Pathogènes Hydriques Santé Environnements, Université de Montpellier, CNRS, IRD, Montpellier, France
| | - Jean-Luc Jeannot
- UMR 5569 HydroSciences Montpellier, Equipe Pathogènes Hydriques Santé Environnements, Université de Montpellier, CNRS, IRD, Montpellier, France
| | - Estelle Jumas-Bilak
- UMR 5569 HydroSciences Montpellier, Equipe Pathogènes Hydriques Santé Environnements, Université de Montpellier, CNRS, IRD, Montpellier, France
| | - Patrice Got
- MARBEC UMR 9190 (CNRS-IRD-Ifremer-UM), F34095 Montpellier, France
| | - Yannick Gueguen
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan, Via Domitia, France
| | | | - Evelyne Bachère
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan, Via Domitia, France
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22
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Whittington RJ, Paul-Pont I, Evans O, Hick P, Dhand NK. Counting the dead to determine the source and transmission of the marine herpesvirus OsHV-1 in Crassostrea gigas. Vet Res 2018; 49:34. [PMID: 29636093 PMCID: PMC5891919 DOI: 10.1186/s13567-018-0529-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 03/21/2018] [Indexed: 02/08/2023] Open
Abstract
Marine herpesviruses are responsible for epizootics in economically, ecologically and culturally significant taxa. The recent emergence of microvariants of Ostreid herpesvirus 1 (OsHV-1) in Pacific oysters Crassostrea gigas has resulted in socioeconomic losses in Europe, New Zealand and Australia however, there is no information on their origin or mode of transmission. These factors need to be understood because they influence the way the disease may be prevented and controlled. Mortality data obtained from experimental populations of C. gigas during natural epizootics of OsHV-1 disease in Australia were analysed qualitatively. In addition we compared actual mortality data with those from a Reed–Frost model of direct transmission and analysed incubation periods using Sartwell’s method to test for the type of epizootic, point source or propagating. We concluded that outbreaks were initiated from an unknown environmental source which is unlikely to be farmed oysters in the same estuary. While direct oyster-to-oyster transmission may occur in larger oysters if they are in close proximity (< 40 cm), it did not explain the observed epizootics, point source exposure and indirect transmission being more common and important. A conceptual model is proposed for OsHV-1 index case source and transmission, leading to endemicity with recurrent seasonal outbreaks. The findings suggest that prevention and control of OsHV-1 in C. gigas will require multiple interventions. OsHV-1 in C. gigas, which is a sedentary animal once beyond the larval stage, is an informative model when considering marine host-herpesvirus relationships.
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Affiliation(s)
| | - Ika Paul-Pont
- School of Veterinary Science, University of Sydney, Camden, NSW, 2570, Australia.,Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539 CNRS/UBO/IRD/IFREMER, Institut Universitaire Européen de la Mer, Technopôle Brest-Iroise, 29280, Plouzané, France
| | - Olivia Evans
- School of Veterinary Science, University of Sydney, Camden, NSW, 2570, Australia.,Department of Agriculture and Water Resources, Canberra, ACT, 2601, Australia
| | - Paul Hick
- School of Veterinary Science, University of Sydney, Camden, NSW, 2570, Australia
| | - Navneet K Dhand
- School of Veterinary Science, University of Sydney, Camden, NSW, 2570, Australia
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23
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Abbadi M, Zamperin G, Gastaldelli M, Pascoli F, Rosani U, Milani A, Schivo A, Rossetti E, Turolla E, Gennari L, Toffan A, Arcangeli G, Venier P. Identification of a newly described OsHV-1 µvar from the North Adriatic Sea (Italy). J Gen Virol 2018; 99:693-703. [PMID: 29580370 PMCID: PMC5994699 DOI: 10.1099/jgv.0.001042] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The surveillance activities for abnormal bivalve mortality events in Italy include the diagnosis of ostreid herpesvirus type 1 (OsHV-1) in symptomatic oysters. OsHV-1-positive oysters (Crassostrea gigas) were used as a source for in vivo virus propagation and a virus-rich sample was selected to perform shotgun sequencing based on Illumina technology. Starting from this unpurified supernatant sample from gills and mantle, we generated 3.5 million reads (2×300 bp) and de novo assembled the whole genome of an Italian OsHV-1 microvariant (OsHV-1-PT). The OsHV-1-PT genome encodes 125 putative ORFs, 7 of which had not previously been predicted in other sequenced Malacoherpesviridae. Overall, OsHV-1-PT displays typical microvariant OsHV-1 genome features, while few polymorphisms (0.08 %) determine its uniqueness. As little is known about the genetic determinants of OsHV-1 virulence, comparing complete OsHV-1 genomes supports a better understanding of the virus pathogenicity and provides new insights into virus-host interactions.
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Affiliation(s)
- Miriam Abbadi
- Istituto Zooprofilattico Sperimentale Delle Venezie, Legnaro (PD), Italy.,Department of Biology, University of Padova, Padova (PD), Italy
| | - Gianpiero Zamperin
- Istituto Zooprofilattico Sperimentale Delle Venezie, Legnaro (PD), Italy
| | | | - Francesco Pascoli
- Istituto Zooprofilattico Sperimentale Delle Venezie, Legnaro (PD), Italy
| | - Umberto Rosani
- Department of Biology, University of Padova, Padova (PD), Italy
| | - Adelaide Milani
- Istituto Zooprofilattico Sperimentale Delle Venezie, Legnaro (PD), Italy
| | - Alessia Schivo
- Istituto Zooprofilattico Sperimentale Delle Venezie, Legnaro (PD), Italy
| | - Emanuele Rossetti
- Consorzio Cooperative Pescatori del Polesine, Scardovari (RO), Italy
| | | | | | - Anna Toffan
- Istituto Zooprofilattico Sperimentale Delle Venezie, Legnaro (PD), Italy
| | - Giuseppe Arcangeli
- Istituto Zooprofilattico Sperimentale Delle Venezie, Legnaro (PD), Italy
| | - Paola Venier
- Department of Biology, University of Padova, Padova (PD), Italy
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24
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Cáceres-Martínez J, Vásquez-Yeomans R, Danigo P, Reyes-Roel C. Histological Alterations in Pacific Oysters Crassostrea gigas that Survived a Summer Mortality Event in Baja California, Mexico. JOURNAL OF AQUATIC ANIMAL HEALTH 2018; 30:31-38. [PMID: 29595887 DOI: 10.1002/aah.10006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 10/23/2017] [Indexed: 06/08/2023]
Abstract
A mortality episode (>90%) of triploid and diploid Pacific oysters Crassostrea gigas cultured in Baja California Sur occurred during summer 2012, coinciding with a thermal anomaly, an algal bloom, and low oxygen values. To help explain the cause of the mortalities, histological analyses and molecular tests for specific pathogens (ostreid herpesvirus 1 [OsHV-1] and Perkinsus marinus) were performed on oysters surviving at the end of the episode. Triploid oysters showed a high percentage of males (43%) and hermaphrodites (30%); 93% of these oysters were in the gonadic reabsorption stage, and in some cases, hemocytes completely filled the lumen of the gonadic follicles. Oysters presented large areas with severe hemocyte infiltration that extended toward the digestive gland. Diploid oysters showed similar gonad alterations. None of samples showed histological or molecular evidence of OsHV-1 or P. marinus. Histological alterations can be related to physiological disorders caused by the mechanism driving summer mortality. This is the first case history of a summer mortality episode among Pacific oysters in Mexico.
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Affiliation(s)
- Jorge Cáceres-Martínez
- Centro de Investigación Científica y de Educación Superior de Ensenada, Carretera Ensenada-Tijuana Number 3918, Zona Playitas, 22860, Ensenada, Baja California, México
| | - Rebeca Vásquez-Yeomans
- Instituto de Sanidad Acuícola, Asociación Civil, Calle de la Marina Sin Número, esquina Caracoles, Fraccionamiento Playa Ensenada, 22880, Ensenada, Baja California, México
| | - Philippe Danigo
- Sol Azul, Sociedad Anónima de Capital Variable, Boulevard Álvaro Obregón 720-2, Colonia El Esterito, 23020, La Paz, Baja California Sur, México
| | - Carlos Reyes-Roel
- Sol Azul, Sociedad Anónima de Capital Variable, Boulevard Álvaro Obregón 720-2, Colonia El Esterito, 23020, La Paz, Baja California Sur, México
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25
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Masood M, Herberstein ME, Raftos DA, Nair SV. Double stranded RNA is processed differently in two oyster species. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2017; 76:285-291. [PMID: 28687485 DOI: 10.1016/j.dci.2017.06.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 06/07/2017] [Accepted: 06/30/2017] [Indexed: 06/07/2023]
Abstract
Ostreid herpes virus causes serious disease in the Pacific oyster (Crassostrea gigas), but not in the Sydney Rock Oyster (Saccostrea glomerata). To investigate differences in disease progression, we injected oysters with double stranded RNA (dsRNA). dsRNA is known to mimic viral infection, and can evoke immune responses when Toll-like receptors detect the dsRNA, leading to the production of type 1 interferon and inflammation cytokines. The uptake and processing of dsRNA was tracked in gill and mantle tissue of Crassostrea gigas and Saccostrea glomerata after injection of fluorochrome labelled poly (I:C) dsRNA. The two species showed significant differences in tissue uptake and clearance, and differences in immune responses confirmed by real time PCR. These results showed that S. glomerata was more efficient in processing dsRNA than C. gigas, and that the gill tissue is an important site of dsRNA processing and response.
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Affiliation(s)
- Muhammad Masood
- Department of Biological Sciences, Macquarie University, NSW 2109, Australia.
| | - Marie E Herberstein
- Department of Biological Sciences, Macquarie University, NSW 2109, Australia
| | - David A Raftos
- Department of Biological Sciences, Macquarie University, NSW 2109, Australia
| | - Sham V Nair
- Department of Biological Sciences, Macquarie University, NSW 2109, Australia
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26
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Detection of Ostreid herpesvirus -1 microvariants in healthy Crassostrea gigas following disease events and their possible role as reservoirs of infection. J Invertebr Pathol 2017; 148:20-33. [DOI: 10.1016/j.jip.2017.05.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 04/30/2017] [Accepted: 05/08/2017] [Indexed: 02/07/2023]
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27
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Martenot C, Gervais O, Chollet B, Houssin M, Renault T. Haemocytes collected from experimentally infected Pacific oysters, Crassostrea gigas: Detection of ostreid herpesvirus 1 DNA, RNA, and proteins in relation with inhibition of apoptosis. PLoS One 2017; 12:e0177448. [PMID: 28542284 PMCID: PMC5436676 DOI: 10.1371/journal.pone.0177448] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 04/27/2017] [Indexed: 11/18/2022] Open
Abstract
Recent transcriptomic approaches focused on anti-viral immunity in molluscs lead to the assumption that the innate immune system, such as apoptosis, plays a crucial role against ostreid herpesvirus type 1 (OsHV-1), infecting Pacific cupped oyster, Crassostrea gigas. Apoptosis constitutes a major mechanism of anti-viral response by limiting viral spread and eliminating infected cells. In this way, an OsHV-1 challenge was performed and oysters were monitored at three times post injection to investigate viral infection and host response: 2h (early after viral injection in the adductor muscle), 24h (intermediate time), and 48h (just before first oyster mortality record). Virus infection, associated with high cumulative mortality rates (74% and 100%), was demonstrated in haemocytes by combining several detection techniques such as real-time PCR, real-time RT PCR, immunofluorescence assay, and transmission electron microscopy examination. High viral DNA amounts ranged from 5.46×104 to 3.68×105 DNA copies ng-1 of total DNA, were detected in dead oysters and an increase of viral transcripts was observed from 2, 24, and 48hpi for the five targeted OsHV-1 genes encoding three putative membrane proteins (ORFs 25, 41, and 72), a putative dUTPase (ORF 75), and a putative apoptosis inhibitor (ORF 87). Apoptosis was studied at molecular and cellular levels with an early marker (phosphatidyl-serine externalisation measured by flow cytometry and epifluorescence microscopy) and a later parameter (DNA fragmentation by terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling assay (TUNEL)). The down-regulation of genes encoding proteins involved in the activation of the apoptotic pathway (TNF and caspase 3) and the up-regulation of genes encoding anti-apoptotic proteins (IAP-2, and Bcl-2) suggested an important anti-apoptosis phenomenon in haemocytes from OsHV-1 infected oysters at 24 and 48hpi. Additionally, more phosphatidyl-serines were externalized and more cells with DNA fragmentation were observed in haemocytes collected from artificial seawater injected oysters than in haemocytes collected from OsHV-1 infected oysters at 24 and 48hpi, suggesting an inhibition of the apoptotic process in presence of the virus. In conclusion, this study is the first to focus on C. gigas haemocytes, cells involved in the host immune defense, during an OsHV-1 challenge in controlled conditions by combining various and original approaches to investigate apoptosis at molecular and cellular levels.
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Affiliation(s)
- Claire Martenot
- Ifremer (Institut Français de Recherche pour l'Exploitation de la Mer), Laboratoire de Génétique et Pathologie des Mollusques Marins, La Tremblade, France
- * E-mail:
| | - Ophélie Gervais
- Ifremer (Institut Français de Recherche pour l'Exploitation de la Mer), Laboratoire de Génétique et Pathologie des Mollusques Marins, La Tremblade, France
| | - Bruno Chollet
- Ifremer (Institut Français de Recherche pour l'Exploitation de la Mer), Laboratoire de Génétique et Pathologie des Mollusques Marins, La Tremblade, France
| | | | - Tristan Renault
- Ifremer, Département Ressources Biologiques et Environnement, Nantes, France
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28
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Carrasco N, Gairin I, Pérez J, Andree KB, Roque A, Fernández-Tejedor M, Rodgers CJ, Aguilera C, Furones MD. A Production Calendar Based on Water Temperature, Spat Size, and Husbandry Practices Reduce OsHV-1 μvar Impact on Cultured Pacific Oyster Crassostrea gigas in the Ebro Delta (Catalonia), Mediterranean Coast of Spain. Front Physiol 2017; 8:125. [PMID: 28316573 PMCID: PMC5334345 DOI: 10.3389/fphys.2017.00125] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 02/15/2017] [Indexed: 11/13/2022] Open
Abstract
Since 2006, the production of Pacific oyster Crassostrea gigas in the Ebro Delta area has dramatically declined from around 800 metric tons (MT) per year to 138 MT in 2011. This decline in production has had a significant socio-economic impact in a region where the shellfish sector is a traditional economic activity for many families. The identified agent responsible for this reduction in C. gigas production was Ostreid Herpesvirus microvar (OsHV-1 μvar), which has been associated with C. gigas spat mortalities in France, and in many other countries. In Spain the episodes of mortality became critical for the regional shellfish production between 2008 until 2014, with mortality percentage up to 100%. In this study, local hatchery C. gigas spat was used as sentinel animals for epidemiological studies and management tests carried out with the aim of reducing oyster mortality in the Ebro Delta area. A production calendar mainly based on water temperature dynamics was designed around an optimal schedule for spat immersion. The immersion calendar included two optimal periods for spat immersion, in summer when temperatures are ≥25°C and at the end of autumn and beginning of winter when they are ≤13°C. Such production planning has reduced mortalities from 80% (in 2014 and previous years) to 2-7.5% in 2015 in cemented oysters. Furthermore, other recommendations related to spat immersion size, culture density and methodology, and cementing calendar, which helped to achieve the results presented, were also recorded and transferred to local producers. This work presents a successfully tested management strategy reducing OsHV-1 μvar impact by designing new field management practices mainly focused on the handling and timing of spat immersion. This approach could be used as a management model in areas presenting similar production practices and environmental characteristics.
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Affiliation(s)
- Noèlia Carrasco
- Institute for Research and Technology in Food and Agriculture Sant Carles de la Ràpita, Spain
| | - Ignasi Gairin
- Institute for Research and Technology in Food and Agriculture Sant Carles de la Ràpita, Spain
| | - Josu Pérez
- Institute for Research and Technology in Food and Agriculture Sant Carles de la Ràpita, Spain
| | - Karl B Andree
- Institute for Research and Technology in Food and Agriculture Sant Carles de la Ràpita, Spain
| | - Ana Roque
- Institute for Research and Technology in Food and Agriculture Sant Carles de la Ràpita, Spain
| | | | - Chris J Rodgers
- Institute for Research and Technology in Food and Agriculture Sant Carles de la Ràpita, Spain
| | - Cristobal Aguilera
- Institute for Research and Technology in Food and Agriculture Sant Carles de la Ràpita, Spain
| | - M Dolors Furones
- Institute for Research and Technology in Food and Agriculture Sant Carles de la Ràpita, Spain
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29
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Arzul I, Corbeil S, Morga B, Renault T. Viruses infecting marine molluscs. J Invertebr Pathol 2017; 147:118-135. [PMID: 28189502 DOI: 10.1016/j.jip.2017.01.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Revised: 01/20/2017] [Accepted: 01/23/2017] [Indexed: 11/19/2022]
Abstract
Although a wide range of viruses have been reported in marine molluscs, most of these reports rely on ultrastructural examination and few of these viruses have been fully characterized. The lack of marine mollusc cell lines restricts virus isolation capacities and subsequent characterization works. Our current knowledge is mostly restricted to viruses affecting farmed species such as oysters Crassostrea gigas, abalone Haliotis diversicolor supertexta or the scallop Chlamys farreri. Molecular approaches which are needed to identify virus affiliation have been carried out for a small number of viruses, most of them belonging to the Herpesviridae and birnaviridae families. These last years, the use of New Generation Sequencing approach has allowed increasing the number of sequenced viral genomes and has improved our capacity to investigate the diversity of viruses infecting marine molluscs. This new information has in turn allowed designing more efficient diagnostic tools. Moreover, the development of experimental infection protocols has answered some questions regarding the pathogenesis of these viruses and their interactions with their hosts. Control and management of viral diseases in molluscs mostly involve active surveillance, implementation of effective bio security measures and development of breeding programs. However factors triggering pathogen development and the life cycle and status of the viruses outside their mollusc hosts still need further investigations.
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Affiliation(s)
- Isabelle Arzul
- Ifremer, SG2M-LGPMM, Station La Tremblade, 17390 La Tremblade, France
| | - Serge Corbeil
- CSIRO Australian Animal Health Laboratory, 5 Portarlington Road, Geelong East, Victoria 3220, Australia
| | - Benjamin Morga
- Ifremer, SG2M-LGPMM, Station La Tremblade, 17390 La Tremblade, France
| | - Tristan Renault
- Ifremer, RBE, Centre Atlantique, Rue de l'Ile d'Yeu, BP 21105, 44311 Nantes Cedex 03, France.
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30
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Evans O, Paul-Pont I, Whittington RJ. Detection of ostreid herpesvirus 1 microvariant DNA in aquatic invertebrate species, sediment and other samples collected from the Georges River estuary, New South Wales, Australia. DISEASES OF AQUATIC ORGANISMS 2017; 122:247-255. [PMID: 28117303 DOI: 10.3354/dao03078] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Ostreid herpesvirus 1 microvariants (OsHV-1) present a serious threat to the Australian Crassostrea gigas industry. Of great concern is the propensity for mortality due to the virus recurring each season in farmed oysters. However, the source of the virus in recurrent outbreaks remains unclear. Reference strain ostreid herpesvirus 1 (OsHV-1 ref) and other related variants have been detected in several aquatic invertebrate species other than C. gigas in Europe, Asia and the USA. The aim of this study was to confirm the presence or absence of OsHV-1 in a range of opportunistically sampled aquatic invertebrate species inhabiting specific locations within the Georges River estuary in New South Wales, Australia. OsHV-1 DNA was detected in samples of wild C. gigas, Saccostrea glomerata, Anadara trapezia, mussels (Mytilus spp., Trichomya hirsuta), whelks (Batillaria australis or Pyrazus ebeninus) and barnacles Balanus spp. collected from several sites between October 2012 and April 2013. Viral loads in non-ostreid species were consistently low, as was the prevalence of OsHV-1 DNA detection. Viral concentrations were highest in wild C. gigas and S. glomerata; the prevalence of detectable OsHV-1 DNA in these oysters reached approximately 68 and 43%, respectively, at least once during the study. These species may be important to the transmission and/or persistence of OsHV-1 in endemically infected Australian estuaries.
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Affiliation(s)
- Olivia Evans
- Faculty of Veterinary Science, School of Life and Environmental Sciences, The University of Sydney, Camden, NSW 2570, Australia
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Pernet F, Lupo C, Bacher C, Whittington RJ. Infectious diseases in oyster aquaculture require a new integrated approach. Philos Trans R Soc Lond B Biol Sci 2016; 371:rstb.2015.0213. [PMID: 26880845 DOI: 10.1098/rstb.2015.0213] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Emerging diseases pose a recurrent threat to bivalve aquaculture. Recently, massive mortality events in the Pacific oyster Crassostrea gigas associated with the detection of a microvariant of the ostreid herpesvirus 1 (OsHV-1µVar) have been reported in Europe, Australia and New Zealand. Although the spread of disease is often viewed as a governance failure, we suggest that the development of protective measures for bivalve farming is presently held back by the lack of key scientific knowledge. In this paper, we explore the case for an integrated approach to study the management of bivalve disease, using OsHV-1 as a case study. Reconsidering the key issues by incorporating multidisciplinary science could provide a holistic understanding of OsHV-1 and increase the benefit of research to policymakers.
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Affiliation(s)
- Fabrice Pernet
- UMR LEMAR 6539 (UBO/CNRS/IRD/Ifremer), Ifremer, Technopôle Brest Iroise, BP 70, Plouzané 29280, France
| | - Coralie Lupo
- Laboratoire de Génétique et Pathologie des Mollusques Marins, Ifremer-SG2M-LGPMM, Avenue Mus de Loup, La Tremblade 17390, France
| | - Cédric Bacher
- Dyneco/BENTHOS, Ifremer, Technopôle Brest Iroise, BP 70, Plouzané 29280, France
| | - Richard J Whittington
- Faculty of Veterinary Science, The University of Sydney, 425 Werombi Road, Camden, New South Wales 2570, Australia
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Bueno R, Perrott M, Dunowska M, Brosnahan C, Johnston C. In situ hybridization and histopathological observations during ostreid herpesvirus-1-associated mortalities in Pacific oysters Crassostrea gigas. DISEASES OF AQUATIC ORGANISMS 2016; 122:43-55. [PMID: 27901503 DOI: 10.3354/dao03062] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In a previous longitudinal study conducted during a mortality investigation associated with ostreid herpesvirus-1 (OsHV-1) microvariant in New Zealand Pacific oysters in 2010-2011, temporality of OsHV-1 nucleic acid detection by real-time PCR assay and onset of Pacific oyster mortality was observed. The present study further elucidated the role of OsHV-1 using an in situ hybridization (ISH) assay on sections of Pacific oysters collected from the same longitudinal study. Hybridization of the labelled probe with the target region of the OsHV-1 genome in infected cells was detected colorimetrically using nitro blue tetrazolium (NBT). OsHV-1 presence and distribution in spat indicated by the ISH signal was then compared with the existence of pathological changes in oyster tissues. Dark blue to purplish black NBT cell labelling was seen predominantly in the stroma of the mantle and gills at Day 5 post introduction to the farm. The distribution and location of ISH signals indicated the extent of OsHV-1-infected cells in multiple tissues. Histopathological abnormalities were mostly non-specific; however, a progressive pattern of increasingly widespread haemocytosis coincided with the appearance of OsHV-1-infected cells in spat collected at different time-points. The visualisation of an increasing number of OsHV-1-positive cells in spat prior to a marked increase in mortality indicated the strong likelihood of an on-going and active viral infection in some oysters. Further studies are recommended to elucidate OsHV-1 pathogenesis in Pacific oysters in association with other potentially causal variables, such as elevated temperature and interaction with Vibrio spp. bacteria.
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Affiliation(s)
- Rudolfo Bueno
- Animal Health Laboratory, Investigation, Diagnostic Centres and Response-Wallaceville, Ministry for Primary Industries, 66 Ward St, PO Box 40742, Upper Hutt 5018, New Zealand
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Prado-Alvarez M, Darmody G, Hutton S, O'Reilly A, Lynch SA, Culloty SC. Occurrence of OsHV-1 in Crassostrea gigas Cultured in Ireland during an Exceptionally Warm Summer. Selection of Less Susceptible Oysters. Front Physiol 2016; 7:492. [PMID: 27877131 PMCID: PMC5099240 DOI: 10.3389/fphys.2016.00492] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 10/11/2016] [Indexed: 11/13/2022] Open
Abstract
The occurrence of OsHV-1, a herpes virus causing mass mortality in the Pacific oyster Crassostrea gigas was investigated with the aim to select individuals with different susceptibility to the infection. Naïve spat transferred to infected areas and juveniles currently being grown at those sites were analyzed using molecular and histology approaches. The survey period distinguishes itself by very warm temperatures reaching up to 3.5°C above the average. The virus was not detected in the virus free area although a spread of the disease could be expected due to high temperatures. Overall mortality, prevalence of infection and viral load was higher in spat confirming the higher susceptibility in early life stages. OsHV-1 and oyster mortality were detected in naïve spat after 15 days of cohabitation with infected animals. Although, infection was associated with mortality in spat, the high seawater temperatures could also be the direct cause of mortality at the warmest site. One stock of juveniles suffered an event of abnormal mortality that was significantly associated with OsHV-1 infection. Those animals were infected with a previously undescribed microvariant whereas the other stocks were infected with OsHV-1 μVar. Cell lesions due to the infection were observed by histology and true infections were corroborated by in situ hybridization. Survivors from the natural outbreak were exposed to OsHV-1 μVar by intramuscular injection and were compared to naïve animals. The survival rate in previously exposed animals was significantly higher than in naïve oysters. Results derived from this study allowed the selection of animals that might possess interesting characteristics for future analysis on OsHV-1 resistance.
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Affiliation(s)
- Maria Prado-Alvarez
- Aquaculture and Fisheries Development Centre, School of Biological, Earth and Environmental Science and Environmental Research Institute, University College Cork Cork, Ireland
| | - Grainne Darmody
- Aquaculture and Fisheries Development Centre, School of Biological, Earth and Environmental Science and Environmental Research Institute, University College Cork Cork, Ireland
| | - Stephen Hutton
- Aquaculture and Fisheries Development Centre, School of Biological, Earth and Environmental Science and Environmental Research Institute, University College Cork Cork, Ireland
| | - Amy O'Reilly
- Aquaculture and Fisheries Development Centre, School of Biological, Earth and Environmental Science and Environmental Research Institute, University College Cork Cork, Ireland
| | - Sharon A Lynch
- Aquaculture and Fisheries Development Centre, School of Biological, Earth and Environmental Science and Environmental Research Institute, University College Cork Cork, Ireland
| | - Sarah C Culloty
- Aquaculture and Fisheries Development Centre, School of Biological, Earth and Environmental Science and Environmental Research Institute, University College Cork Cork, Ireland
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Antiviral Activity of Myticin C Peptide from Mussel: an Ancient Defense against Herpesviruses. J Virol 2016; 90:7692-702. [PMID: 27307570 DOI: 10.1128/jvi.00591-16] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 06/08/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Little is known about the antiviral response in mollusks. As in other invertebrates, the interferon signaling pathways have not been identified, and in fact, there is a debate about whether invertebrates possess antiviral immunity similar to that of vertebrates. In marine bivalves, due to their filtering activity, interaction with putative pathogens, including viruses, is very high, suggesting that they should have mechanisms to address these infections. In this study, we confirmed that constitutively expressed molecules in naive mussels confer resistance in oysters to ostreid herpesvirus 1 (OsHV-1) when oyster hemocytes are incubated with mussel hemolymph. Using a proteomic approach, myticin C peptides were identified in both mussel hemolymph and hemocytes. Myticins, antimicrobial peptides that have been previously characterized, were constitutively expressed in a fraction of mussel hemocytes and showed antiviral activity against OsHV-1, suggesting that these molecules could be responsible for the antiviral activity of mussel hemolymph. For the first time, a molecule from a bivalve has shown antiviral activity against a virus affecting mollusks. Moreover, myticin C peptides showed antiviral activity against human herpes simplex viruses 1 (HSV-1) and 2 (HSV-2). In summary, our work sheds light on the invertebrate antiviral immune response with the identification of a molecule with potential biotechnological applications. IMPORTANCE Several bioactive molecules that have potential pharmaceutical or industrial applications have been identified and isolated from marine invertebrates. Myticin C, an antimicrobial peptide from the Mediterranean mussel (Mytilus galloprovincialis) that was identified by proteomic techniques in both mussel hemolymph and hemocytes, showed potential as an antiviral agent against ostreid herpesvirus 1 (OsHV-1), which represents a major threat to the oyster-farming sector. Both hemolymph from mussels and a myticin C peptide inhibited OsHV-1 replication in oyster hemocytes. Additionally, a modified peptide derived from myticin C or the nanoencapsulated normal peptide also showed antiviral activity against the human herpesviruses HSV-1 and HSV-2. Therefore, myticin C is an example of the biotechnological and therapeutic potential of mollusks.
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Masood M, Raftos DA, Nair SV. Two Oyster Species That Show Differential Susceptibility to Virus Infection Also Show Differential Proteomic Responses to Generic dsRNA. J Proteome Res 2016; 15:1735-46. [PMID: 27072892 DOI: 10.1021/acs.jproteome.5b00615] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Viral diseases are a significant cause of mortality and morbidity in oysters, resulting in significant economic losses. We investigated the proteomic responses of these two species of oysters to generic double-stranded RNAs (poly I:C and poly A:U). Analysis of proteomic data using isobaric tags for relative and absolute quantitaion (iTRAQ) indicated that there were significant differences in the proteomic responses of the two oyster species resulting from this treatment. Gene ontology analysis showed that several biological processes, cellular components, and molecular function were unique to the different data sets. For example, a number of proteins implicated in the TLR signaling pathway were associated with the Saccostrea glomerata data set but were absent in the Crassostra gigas data set. These results suggest that the differences in the proteomic responses to dsRNA may underpin the biological differences in viral susceptibility. Molecular targets previously shown to be expressed in C. gigas in response to OsHV1 infections were not present in our proteomic data sets, although they were present in the RNA extracted from the very same tissues. Taken together, our data indicate that there are substantial disparities between transcriptomic and proteomic responses to dsRNA challenge, and a comprehensive account of the oysters' biological responses to these treatments must take into account that disparity.
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Affiliation(s)
- Muhammad Masood
- Department of Biological Sciences, Macquarie University , NSW 2109 Australia
| | - David A Raftos
- Department of Biological Sciences, Macquarie University , NSW 2109 Australia
| | - Sham V Nair
- Department of Biological Sciences, Macquarie University , NSW 2109 Australia
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In situ localization and tissue distribution of ostreid herpesvirus 1 proteins in infected Pacific oyster, Crassostrea gigas. J Invertebr Pathol 2016; 136:124-35. [PMID: 27066775 DOI: 10.1016/j.jip.2016.04.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 04/06/2016] [Accepted: 04/07/2016] [Indexed: 11/20/2022]
Abstract
Immunohistochemistry (IHC) assays were conducted on paraffin sections from experimentally infected spat and unchallenged spat produced in hatchery to determine the tissue distribution of three viral proteins within the Pacific oyster, Crassostrea gigas. Polyclonal antibodies were produced from recombinant proteins corresponding to two putative membrane proteins and one putative apoptosis inhibitor encoded by ORF 25, 72, and 87, respectively. Results were then compared to those obtained by in situ hybridization performed on the same individuals, and showed a substantial agreement according to Landis and Koch numeric scale. Positive signals were mainly observed in connective tissue of gills, mantle, adductor muscle, heart, digestive gland, labial palps, and gonads of infected spat. Positive signals were also reported in digestive epithelia. However, few positive signals were also observed in healthy appearing oysters (unchallenged spat) and could be due to virus persistence after a primary infection. Cellular localization of staining seemed to be linked to the function of the viral protein targeted. A nucleus staining was preferentially observed with antibodies targeting the putative apoptosis inhibitor protein whereas a cytoplasmic localization was obtained using antibodies recognizing putative membrane proteins. The detection of viral proteins was often associated with histopathological changes previously reported during OsHV-1 infection by histology and transmission electron microscopy. Within the 6h after viral suspension injection, positive signals were almost at the maximal level with the three antibodies and all studied organs appeared infected at 28h post viral injection. Connective tissue appeared to be a privileged site for OsHV-1 replication even if positive signals were observed in the epithelium cells of different organs which may be interpreted as a hypothetical portal of entry or release for the virus. IHC constitutes a suited method for analyzing the early infection stages of OsHV-1 infection and a useful tool to investigate interactions between OsHV-1 and its host at a protein level.
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Thrush MA, Pearce FM, Gubbins MJ, Oidtmann BC, Peeler EJ. A Simple Model to Rank Shellfish Farming Areas Based on the Risk of Disease Introduction and Spread. Transbound Emerg Dis 2016; 64:1200-1209. [DOI: 10.1111/tbed.12492] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Indexed: 12/01/2022]
Affiliation(s)
- M. A. Thrush
- Centre for Environment, Fisheries and Aquaculture Science (Cefas); Weymouth UK
| | - F. M. Pearce
- Ministry for Primary Industries; Wellington New Zealand
| | - M. J. Gubbins
- Centre for Environment, Fisheries and Aquaculture Science (Cefas); Weymouth UK
| | - B. C. Oidtmann
- Centre for Environment, Fisheries and Aquaculture Science (Cefas); Weymouth UK
| | - E. J. Peeler
- Centre for Environment, Fisheries and Aquaculture Science (Cefas); Weymouth UK
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38
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Whittington R, Hick P, Evans O, Rubio A, Dhand N, Paul-Pont I. Pacific oyster mortality syndrome: a marine herpesvirus active in Australia. MICROBIOLOGY AUSTRALIA 2016. [DOI: 10.1071/ma16043] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Genotypes of Ostreid herpesvirus 1 (OsHV-1) known as microvariants cause the disease Pacific oyster mortality syndrome (POMS). Since its appearance in NSW in 2010, OsHV-1 microvariant has prevented the farming of Pacific oysters (Crassostrea gigas) in the affected estuaries near Sydney, following the initial massive outbreaks1,2. The arrival of the disease in southeast Tasmania in January 2016 has put the entire $53M industry in Australia in jeopardy3. The virus is a member of the Family Malacoherpesviridae4, which includes several invertebrate herpesviruses. The OsHV-1 genome consists of 207 439 base pairs, with organisation similar to that of mammalian herpesviruses. However, OsHV-1 contains two invertible unique regions (UL, 167.8 kbp; US, 3.4 kbp) each flanked by inverted repeats (TRL/IRL, 7.6 kbp; TRS/IRS, 9.8 kbp), with an additional unique sequence (X, 1.5 kbp) between IRL and IRS4. Unlike many herpesviruses which are host specific, OsHV-1 strains have been transmitted between marine bivalve species5 and the virus is transmitted indirectly. The virus may have relatively prolonged survival in the environment, has extremely high infection and case fatality rates, and latency is unproven. Along with pilchard herpesvirus6–8 and abalone ganglioneuritis virus9,10, it is part of a dawning reality that marine herpesviruses are among the most virulent of pathogens. Finding solutions for industry requires more than laboratory-based research.
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Barbosa Solomieu V, Renault T, Travers MA. Mass mortality in bivalves and the intricate case of the Pacific oyster, Crassostrea gigas. J Invertebr Pathol 2015. [PMID: 26210497 DOI: 10.1016/j.jip.2015.07.011] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Massive mortality outbreaks in cultured bivalves have been reported worldwide and they have been associated with infection by a range of viral and bacterial pathogens. Due to their economic and social impact, these episodes constitute a particularly sensitive issue in Pacific oyster (Crassostrea gigas) production. Since 2008, mortality outbreaks affecting C. gigas have increased in terms of intensity and geographic distribution. Epidemiologic surveys have lead to the incrimination of pathogens, specifically OsHV-1 and bacteria of the Vibrio genus, in particular Vibrio aestuarianus. Pathogen diversity may partially account for the variability in the outcome of infections. Host factors (age, reproductive status...) including their genetic background that has an impact on host susceptibility toward infection, also play a role herein. Finally, environmental factors have significant effects on the pathogens themselves, on the host and on the host-pathogen interaction. Further knowledge on pathogen diversity, classification, and spread, may contribute toward a better understanding of this issue and potential ways to mitigate the impact of these outbreaks.
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Affiliation(s)
- Valérie Barbosa Solomieu
- Université de Bretagne Occidentale, Direction Europe et International, Présidence, 3 rue des Archives, CS93837, 29238 Brest CEDEX 3, France
| | - Tristan Renault
- Ifremer, Unité Santé Génétique Microbiologie des Mollusques (SG2M), Laboratoire de Génétique et Pathologie des Mollusques Marins (LGPMM), 17390 La Tremblade, France.
| | - Marie-Agnès Travers
- Ifremer, Unité Santé Génétique Microbiologie des Mollusques (SG2M), Laboratoire de Génétique et Pathologie des Mollusques Marins (LGPMM), 17390 La Tremblade, France
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40
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41
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Tan TLS, Paul-Pont I, Evans OM, Watterson D, Young P, Whittington R, Fougerouse A, Bichet H, Barnes AC, Dang C. Resistance of Black-lip learl oyster, Pinctada margaritifera, to infection by Ostreid herpes virus 1μvar under experimental challenge may be mediated by humoral antiviral activity. FISH & SHELLFISH IMMUNOLOGY 2015; 44:232-240. [PMID: 25712854 DOI: 10.1016/j.fsi.2015.02.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 01/19/2015] [Accepted: 02/14/2015] [Indexed: 06/04/2023]
Abstract
Ostreid herpesvirus 1 (OsHV-1) has induced mass mortalities of the larvae and spat of Pacific oysters, Crassostrea gigas, in Europe and, more recently, in Oceania. The production of pearls from the Black-lip pearl oyster, Pinctada margaritifera, represents the second largest source of income to the economies of French Polynesia and many Pacific Island nations that could be severely compromised in the event of a disease outbreak. Coincidentally with the occurrence of OsHV-1 in the southern hemisphere, C. gigas imported from New Zealand and France into French Polynesia tested positive for OsHV-1. Although interspecies viral transmission has been demonstrated, the transmissibility of OsHV-1 to P. margaritifera is unknown. We investigated the susceptibility of juvenile P. margaritifera to OsHV-1 μvar that were injected with tissue homogenates sourced from either naturally infected or healthy C. gigas. The infection challenge lasted 14 days post-injection (dpi) with sampling at 0, 1, 2, 3, 5, 7 and 14 days. Mortality rate, viral prevalence, and cellular immune responses in experimental animals were determined. Tissues were screened by light microscopy and TEM. Pacific oysters were also challenged and used as a positive control to validate the efficiency of OsHV-1 μvar infection. Viral particles and features such as marginated chromatin and highly electron dense nuclei were observed in C. gigas but not in P. margaritifera. Mortality rates and hemocyte immune parameters, including phagocytosis and respiratory burst, were similar between challenged and control P. margaritifera. Herpesvirus-inhibiting activity was demonstrated in the acellular fraction of the hemolymph from P. margaritifera, suggesting that the humoral immunity is critical in the defence against herpesvirus in pearl oysters. Overall, these results suggest that under the conditions of the experimental challenge, P. margaritifera was not sensitive to OsHV-1 μvar and was not an effective host/carrier. The nature and spectrum of activity of the humoral antiviral activity is worthy of further investigation.
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Affiliation(s)
- Terence L S Tan
- The University of Queensland, School of Biological Sciences and Centre for Marine Science, Brisbane, Queensland 4072, Australia
| | - Ika Paul-Pont
- The University of Sydney, Faculty of Veterinary Science, Camden, New South Wales 2570, Australia
| | - Olivia M Evans
- The University of Sydney, Faculty of Veterinary Science, Camden, New South Wales 2570, Australia
| | - Daniel Watterson
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Paul Young
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Richard Whittington
- The University of Sydney, Faculty of Veterinary Science, Camden, New South Wales 2570, Australia
| | | | - Hervé Bichet
- Direction des Ressources Marines, Papeete, French Polynesia
| | - Andrew C Barnes
- The University of Queensland, School of Biological Sciences and Centre for Marine Science, Brisbane, Queensland 4072, Australia.
| | - Cécile Dang
- The University of Queensland, School of Biological Sciences and Centre for Marine Science, Brisbane, Queensland 4072, Australia
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Paul-Pont I, Evans O, Dhand NK, Whittington RJ. Experimental infections of Pacific oyster Crassostrea gigas using the Australian ostreid herpesvirus-1 (OsHV-1) µVar strain. DISEASES OF AQUATIC ORGANISMS 2015; 113:137-147. [PMID: 25751856 DOI: 10.3354/dao02826] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In Australia, the spread of the ostreid herpesvirus-1 microvariant (OsHV-1 µVar) threatens the Pacific oyster industry. There is an urgent need to develop an experimental infection model in order to study the pathogenesis of the virus under controlled laboratory conditions. The present study constitutes the first attempt to use archived frozen oysters as a source of inoculum, based on the Australian OsHV-1 µVar strain. Experiments were conducted to test (1) virus infectivity, (2) the dose-response relationship for OsHV-1, and (3) the best conditions in which to store infective viral inoculum. Intramuscular injection of a viral inoculum consistently led to an onset of mortality 48 h post-injection and a final cumulative mortality exceeding 90%, in association with high viral loads (1 × 105 to 3 × 107 copies of virus mg-1) in dead individuals. For the first time, an infective inoculum was produced from frozen oysters (tissues stored at -80°C for 6 mo). Storage of purified viral inoculum at +4°C for 3 mo provided similar results to use of fresh inoculum, whereas storage at -20°C, -80°C and room temperature was detrimental to infectivity. A dose-response relationship for OsHV-1 was identified but further research is recommended to determine the most appropriate viral concentration for development of infection models that would be used for different purposes. Overall, this work highlights the best practices and potential issues that may occur in the development of a reproducible and transferable infection model for studying the pathogenicity of the Australian OsHV-1 strain in Crassostrea gigas under experimental conditions.
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Affiliation(s)
- Ika Paul-Pont
- Faculty of Veterinary Science, The University of Sydney, 425 Werombi Road, Camden, NSW 2570, Australia
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43
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Pande A, Acosta H, Brangenberg NA, Keeling SE. Design of a detection survey for Ostreid herpesvirus-1 using hydrodynamic dispersion models to determine epidemiological units. Prev Vet Med 2015; 119:80-4. [PMID: 25746929 DOI: 10.1016/j.prevetmed.2015.02.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 02/05/2015] [Accepted: 02/13/2015] [Indexed: 11/30/2022]
Abstract
Using Ostreid herpesvirus-1 (OsHV-1) as a case study, this paper considers a survey design methodology for an aquatic animal pathogen that incorporates the concept of biologically independent epidemiological units. Hydrodynamically-modelled epidemiological units are used to divide marine areas into sensible sampling units for detection surveys of waterborne diseases. In the aquatic environment it is difficult to manage disease at the animal level, hence management practices are often aimed at a group of animals sharing a similar risk. Using epidemiological units is a way to define these groups, based on a similar level of probability of exposure based on the modelled potential spread of a viral particle via coastal currents, that can help inform management decisions.
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Affiliation(s)
- Anjali Pande
- Ministry for Primary Industries, PO Box 2526, Wellington 6140, New Zealand.
| | - Hernando Acosta
- Ministry for Primary Industries, PO Box 2526, Wellington 6140, New Zealand
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44
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Rosani U, Varotto L, Domeneghetti S, Arcangeli G, Pallavicini A, Venier P. Dual analysis of host and pathogen transcriptomes in ostreid herpesvirus 1-positive Crassostrea gigas. Environ Microbiol 2014; 17:4200-12. [PMID: 25384719 DOI: 10.1111/1462-2920.12706] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 10/30/2014] [Accepted: 10/30/2014] [Indexed: 12/13/2022]
Abstract
Ostreid herpesvirus type 1 (OsHV-1) has become a problematic infective agent for the Pacific oyster Crassostrea gigas. In particular, the OsHV-1 μVar subtype has been associated with severe mortality episodes in oyster spat and juvenile oysters in France and other regions of the world. Factors enhancing the infectivity of the virus and its interactions with susceptible and resistant bivalve hosts are still to be understood, and only few studies have explored the expression of oyster or viral genes during productive infections. In this work, we have performed a dual RNA sequencing analysis on an oyster sample with a high viral load. High sequence coverage allowed us to thoroughly explore the OsHV-1 transcriptome and identify the activated molecular pathways in C. gigas. The identification of several highly induced and defence-related oyster transcripts supports the crucial role played by the innate immune system against the virus and opportunistic microbes possibly contributing to subsequent spat mortality.
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Affiliation(s)
- U Rosani
- Department of Biology, University of Padua, via U. Bassi 58/b, 35121, Padua, Italy
| | - L Varotto
- Department of Biology, University of Padua, via U. Bassi 58/b, 35121, Padua, Italy
| | - S Domeneghetti
- Department of Biology, University of Padua, via U. Bassi 58/b, 35121, Padua, Italy
| | - G Arcangeli
- Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe), via L. da Vinci 39, 45011, Adria, Italy
| | - A Pallavicini
- Department of Life Sciences, University of Trieste, via L. Giorgeri 5, 34127, Trieste, Italy
| | - P Venier
- Department of Biology, University of Padua, via U. Bassi 58/b, 35121, Padua, Italy
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45
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Evans O, Paul-Pont I, Hick P, Whittington R. A simple centrifugation method for improving the detection of Ostreid herpesvirus-1 (OsHV-1) in natural seawater samples with an assessment of the potential for particulate attachment. J Virol Methods 2014; 210:59-66. [DOI: 10.1016/j.jviromet.2014.09.023] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 09/20/2014] [Accepted: 09/24/2014] [Indexed: 10/24/2022]
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46
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Domeneghetti S, Varotto L, Civettini M, Rosani U, Stauder M, Pretto T, Pezzati E, Arcangeli G, Turolla E, Pallavicini A, Venier P. Mortality occurrence and pathogen detection in Crassostrea gigas and Mytilus galloprovincialis close-growing in shallow waters (Goro lagoon, Italy). FISH & SHELLFISH IMMUNOLOGY 2014; 41:37-44. [PMID: 24909498 DOI: 10.1016/j.fsi.2014.05.023] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 05/13/2014] [Accepted: 05/15/2014] [Indexed: 06/03/2023]
Abstract
The complex interactions occurring between farmed bivalves and their potential pathogens in the circumstances of global climate changes are current matter of study, owing to the recurrent production breakdowns reported in Europe and other regions of the world. In the frame of Project FP7-KBBE-2010-4 BIVALIFE, we investigated the occurrence of mortality and potential pathogens during the Spring-Summer transition in Crassostrea gigas and Mytilus galloprovincialis cohabiting in the shallow waters of one northern Italian lagoon (Sacca di Goro, Adriatic Sea) and regarded as susceptible and resistant species, respectively. In 2011, limited bivalve mortality was detected in the open-field trial performed with 6-12 month old spat whereas subsequent trials with 2-3 month old spat produced almost complete (2012) and considerable (2013) oyster mortality. Macroscopical examination and histology excluded the presence of notifiable pathogens but, in the sampling preceding the massive oyster spat mortality of 2012, a μdeleted variant of OsHV-1 DNA was found in wide-ranging amounts in all analyzed oysters in conjunction with substantial levels of Vibrio splendidus and Vibrio aestuarianus. The large oyster spat mortality with borderline OsHV-1 positivity recorded in 2013 supports the multi-factorial etiology of the syndrome. This is the first report of a OsHV-1 (under a form interpreted as the variant μVar) in the Goro lagoon. Transcriptional host footprints are under investigation to better understand the bivalve response to environmental factors, included viral and bacterial pathogens, in relation to the observed mortalities.
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Affiliation(s)
| | - Laura Varotto
- Department of Biology, University of Padova, Padova, Italy
| | - Michele Civettini
- Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe, also NRL for Mollusc Diseases), Adria, Italy
| | - Umberto Rosani
- Department of Biology, University of Padova, Padova, Italy
| | - Monica Stauder
- Department of Earth, Environmental and Life Sciences, University of Genova, Italy
| | - Tobia Pretto
- Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe, also NRL for Mollusc Diseases), Adria, Italy
| | - Elisabetta Pezzati
- Department of Earth, Environmental and Life Sciences, University of Genova, Italy
| | - Giuseppe Arcangeli
- Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe, also NRL for Mollusc Diseases), Adria, Italy
| | | | | | - Paola Venier
- Department of Biology, University of Padova, Padova, Italy.
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47
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Development of an in situ hybridization assay for the detection of ostreid herpesvirus type 1 mRNAs in the Pacific oyster, Crassostrea gigas. J Virol Methods 2014; 211:43-50. [PMID: 25455903 DOI: 10.1016/j.jviromet.2014.10.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 10/10/2014] [Accepted: 10/14/2014] [Indexed: 11/21/2022]
Abstract
An in situ hybridization protocol for detecting mRNAs of ostreid herpesvirus type 1 (OsHV-1) which infects Pacific oysters, Crassostrea gigas, was developed. Three RNA probes were synthesized by cloning three partial OsHV-1 genes into plasmids using three specific primer pairs, and performing a transcription in the presence of digoxigenin dUTP. The RNA probes were able to detect the virus mRNAs in paraffin sections of experimentally infected oysters 26 h post-injection. The in situ hybridization showed that the OsHV-1 mRNAs were mainly present in connective tissues in gills, mantle, adductor muscle, digestive gland and gonads. DNA detection by in situ hybridization using a DNA probe and viral DNA quantitation by real-time PCR were also performed and results were compared with those obtained using RNA probes.
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48
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Pernet F, Lagarde F, Jeannée N, Daigle G, Barret J, Le Gall P, Quere C, D’orbcastel ER. Spatial and temporal dynamics of mass mortalities in oysters is influenced by energetic reserves and food quality. PLoS One 2014; 9:e88469. [PMID: 24551106 PMCID: PMC3925110 DOI: 10.1371/journal.pone.0088469] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 01/08/2014] [Indexed: 11/18/2022] Open
Abstract
Although spatial studies of diseases on land have a long history, far fewer have been made on aquatic diseases. Here, we present the first large-scale, high-resolution spatial and temporal representation of a mass mortality phenomenon cause by the Ostreid herpesvirus (OsHV-1) that has affected oysters (Crassostrea gigas) every year since 2008, in relation to their energetic reserves and the quality of their food. Disease mortality was investigated in healthy oysters deployed at 106 locations in the Thau Mediterranean lagoon before the start of the epizootic in spring 2011. We found that disease mortality of oysters showed strong spatial dependence clearly reflecting the epizootic process of local transmission. Disease initiated inside oyster farms spread rapidly beyond these areas. Local differences in energetic condition of oysters, partly driven by variation in food quality, played a significant role in the spatial and temporal dynamics of disease mortality. In particular, the relative contribution of diatoms to the diet of oysters was positively correlated with their energetic reserves, which in turn decreased the risk of disease mortality.
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Affiliation(s)
- Fabrice Pernet
- Ifremer, Laboratoire Environnement Ressource du Languedoc Roussillon, Bd Jean Monnet, Sète, France
- UMR LEMAR Ifremer/CNRS/UBO/IRD, Technopole de Brest-Iroise, Plouzané, France
- * E-mail:
| | - Franck Lagarde
- Ifremer, Laboratoire Environnement Ressource du Languedoc Roussillon, Bd Jean Monnet, Sète, France
| | | | - Gaetan Daigle
- Université Laval, Département de mathématiques et de statistique, Pavillon Alexandre-Vachon, Québec, Québec, Canada
| | - Jean Barret
- Ifremer, Laboratoire Environnement Ressource du Languedoc Roussillon, Bd Jean Monnet, Sète, France
| | - Patrik Le Gall
- Ifremer, Laboratoire Environnement Ressource du Languedoc Roussillon, Bd Jean Monnet, Sète, France
| | - Claudie Quere
- UMR LEMAR Ifremer/CNRS/UBO/IRD, Technopole de Brest-Iroise, Plouzané, France
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49
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Green TJ, Montagnani C, Benkendorff K, Robinson N, Speck P. Ontogeny and water temperature influences the antiviral response of the Pacific oyster, Crassostrea gigas. FISH & SHELLFISH IMMUNOLOGY 2014; 36:151-157. [PMID: 24200990 DOI: 10.1016/j.fsi.2013.10.026] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 10/24/2013] [Accepted: 10/25/2013] [Indexed: 06/02/2023]
Abstract
Disease is caused by a complex interaction between the pathogen, environment, and the physiological status of the host. Determining how host ontogeny interacts with water temperature to influence the antiviral response of the Pacific oysters, Crassostrea gigas, is a major goal in understanding why juvenile Pacific oysters are dying during summer as a result of the global emergence of a new genotype of the Ostreid herpesvirus, termed OsHV-1 μvar. We measured the effect of temperature (12 vs 22 °C) on the antiviral response of adult and juvenile C. gigas injected with poly I:C. Poly I:C up-regulated the expression of numerous immune genes, including TLR, MyD88, IκB-1, Rel, IRF, MDA5, STING, SOC, PKR, Viperin and Mpeg1. At 22 °C, these immune genes showed significant up-regulation in juvenile and adult oysters, but the majority of these genes were up-regulated 12 h post-injection for juveniles compared to 26 h for adults. At 12 °C, the response of these genes was completely inhibited in juveniles and delayed in adults. Temperature and age had no effect on hemolymph antiviral activity against herpes simplex virus (HSV-1). These results suggest that oysters rely on a cellular response to minimise viral replication, involving recognition of virus-associated molecular patterns to induce host cells into an antiviral state, as opposed to producing broad-spectrum antiviral compounds. This cellular response, measured by antiviral gene expression of circulating hemocytes, was influenced by temperature and oyster age. We speculate whether the vigorous antiviral response of juveniles at 22 °C results in an immune-mediated disorder causing mortality.
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Affiliation(s)
- Timothy J Green
- School of Biological Sciences and Australian Seafood Cooperative Research Centre, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia.
| | - Caroline Montagnani
- Ifremer, UMR 5119 Ecology of Coastal Marine Systems, Université Montpellier 2, Place Eugène Bataillon, CC80, 30495 Montpellier cedex 05, France
| | - Kirsten Benkendorff
- Marine Ecology Research Centre, Southern Cross University, P.O. Box 157, Lismore, NSW 2480, Australia
| | - Nick Robinson
- School of Biological Sciences and Australian Seafood Cooperative Research Centre, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia; Nofima, P.O. Box 210, N-1431 Ås, Norway
| | - Peter Speck
- School of Biological Sciences and Australian Seafood Cooperative Research Centre, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia
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50
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Fernández Robledo JA, Vasta GR, Record NR. Protozoan parasites of bivalve molluscs: literature follows culture. PLoS One 2014; 9:e100872. [PMID: 24955977 PMCID: PMC4067406 DOI: 10.1371/journal.pone.0100872] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Accepted: 05/30/2014] [Indexed: 11/18/2022] Open
Abstract
Bivalve molluscs are key components of the estuarine environments as contributors to the trophic chain, and as filter -feeders, for maintaining ecosystem integrity. Further, clams, oysters, and scallops are commercially exploited around the world both as traditional local shellfisheries, and as intensive or semi-intensive farming systems. During the past decades, populations of those species deemed of environmental or commercial interest have been subject to close monitoring given the realization that these can suffer significant decline, sometimes irreversible, due to overharvesting, environmental pollution, or disease. Protozoans of the genera Perkinsus, Haplosporidium, Marteilia, and Bonamia are currently recognized as major threats for natural and farmed bivalve populations. Since their identification, however, the variable publication rates of research studies addressing these parasitic diseases do not always appear to reflect their highly significant environmental and economic impact. Here we analyzed the peer- reviewed literature since the initial description of these parasites with the goal of identifying potential milestone discoveries or achievements that may have driven the intensity of the research in subsequent years, and significantly increased publication rates. Our analysis revealed that after initial description of the parasite as the etiological agent of a given disease, there is a time lag before a maximal number of yearly publications are reached. This has already taken place for most of them and has been followed by a decrease in publication rates over the last decade (20- to 30- year lifetime in the literature). Autocorrelation analyses, however, suggested that advances in parasite purification and culture methodologies positively drive publication rates, most likely because they usually lead to novel molecular tools and resources, promoting mechanistic studies. Understanding these trends should help researchers in prioritizing research efforts for these and other protozoan parasites, together with their development as model systems for further basic and translational research in parasitic diseases.
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Affiliation(s)
| | - Gerardo R. Vasta
- Department of Microbiology and Immunology, University of Maryland Baltimore, School of Medicine, Institute of Marine and Environmental Technology, Baltimore, Maryland, United States of America
| | - Nicholas R. Record
- Bigelow Laboratory for Ocean Sciences, Boothbay, Maine, United States of America
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