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Renault T, Faury N, Morga B. Propidium monoazide PCR, a method to determine OsHV-1 undamaged capsids and to estimate virus Lethal Dose 50. Virus Res 2024; 340:199307. [PMID: 38160910 PMCID: PMC10800765 DOI: 10.1016/j.virusres.2023.199307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 12/27/2023] [Accepted: 12/28/2023] [Indexed: 01/03/2024]
Abstract
Ostreid herpes virus 1 (OsHV-1) has been classified within the Malacoherpesviridae family from the Herpesvirales order. OsHV-1 is the etiological agent of a contagious viral disease of Pacific oysters, C. gigas, affecting also other bivalve species. Mortality rates reported associated with the viral infection vary considerably between sites and countries and depend on the age of affected stocks. A variant called μVar has been reported since 2008 in Europe and other variants in Australia and in New Zealand last decade. These variants are considered as the main causative agents of mass mortality events affecting C. gigas. Presently there is no established cell line that allows for the detection of infectious OsHV-1. In this context, a technique of propidium monoazide (PMA) PCR was developed in order to quantify "undamaged" capsids. This methodology is of interest to explore the virus infectivity. Being able to quantify viral particles getting an undamaged capsid (not only an amount of viral DNA) in tissue homogenates prepared from infected oysters or in seawater samples can assist in the definition of a Lethal Dose (LD) 50 and gain information in the experiments conducted to reproduce the viral infection. The main objectives of the present study were (i) the development/optimization of a PMA PCR technique for OsHV-1 detection using the best quantity of PMA and verifying its effectiveness through heat treatment, (ii) the definition of the percentage of undamaged capsids in four different tissue homogenates prepared from infected Pacific oysters and (iii) the approach of a LD50 during experimental viral infection assays on the basis of a number of undamaged capsids. Although the developped PMA PCR technique was unable to determine OsHV-1 infectivity in viral supensions, it could greatly improve interpretation of virus positive results obtained by qPCR. This technique is not intended to replace the quantification of viral DNA by qPCR, but it does make it possible to give a form of biological meaning to the detection of this DNA.
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Affiliation(s)
- Tristan Renault
- Département Ressources Biologiques et Environnement, Ifremer, Nantes, France.
| | - Nicole Faury
- ASIM, Adaptation Santé des Invertébrés, Ifremer, La Tremblade, France
| | - Benjamin Morga
- ASIM, Adaptation Santé des Invertébrés, Ifremer, La Tremblade, France
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2
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Clerissi C, Luo X, Lucasson A, Mortaza S, de Lorgeril J, Toulza E, Petton B, Escoubas JM, Dégremont L, Gueguen Y, Destoumieux-Garzόn D, Jacq A, Mitta G. A core of functional complementary bacteria infects oysters in Pacific Oyster Mortality Syndrome. Anim Microbiome 2023; 5:26. [PMID: 37138356 PMCID: PMC10155333 DOI: 10.1186/s42523-023-00246-8] [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: 12/05/2022] [Accepted: 04/03/2023] [Indexed: 05/05/2023] Open
Abstract
BACKGROUND The Pacific oyster Crassostrea gigas is one of the main cultivated invertebrate species worldwide. Since 2008, oyster juveniles have been confronted with a lethal syndrome known as the Pacific Oyster Mortality Syndrome (POMS). POMS is a polymicrobial disease initiated by a primary infection with the herpesvirus OsHV-1 µVar that creates an oyster immunocompromised state and evolves towards a secondary fatal bacteremia. RESULTS In the present article, we describe the implementation of an unprecedented combination of metabarcoding and metatranscriptomic approaches to show that the sequence of events in POMS pathogenesis is conserved across infectious environments. We also identified a core bacterial consortium which, together with OsHV-1 µVar, forms the POMS pathobiota. This bacterial consortium is characterized by high transcriptional activities and complementary metabolic functions to exploit host's resources. A significant metabolic specificity was highlighted at the bacterial genus level, suggesting low competition for nutrients between members of the core bacteria. CONCLUSIONS Lack of metabolic competition between the core bacteria might favor complementary colonization of host tissues and contribute to the conservation of the POMS pathobiota across distinct infectious environments.
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Affiliation(s)
- Camille Clerissi
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, CC080, 34095, Montpellier, France
- Université de Perpignan Via Domitia, 58 Avenue Paul Alduy, 66860, Perpignan, France
- CNRS, UAR 3278 CRIOBE, CRIOBE, EPHE, Université PSL, UPVD, 52 Avenue Paul Alduy, 66860, Perpignan Cedex, France
| | - Xing Luo
- CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, 91198, Gif-Sur-Yvette, France
| | - Aude Lucasson
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, CC080, 34095, Montpellier, France
- Université de Perpignan Via Domitia, 58 Avenue Paul Alduy, 66860, Perpignan, France
| | - Shogofa Mortaza
- CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, 91198, Gif-Sur-Yvette, France
| | - Julien de Lorgeril
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, CC080, 34095, Montpellier, France
- Université de Perpignan Via Domitia, 58 Avenue Paul Alduy, 66860, Perpignan, France
- Ifremer, IRD, Univ Nouvelle-Calédonie, Univ La Réunion, ENTROPIE, 98800, Nouméa, Nouvelle-Calédonie, France
| | - Eve Toulza
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, CC080, 34095, Montpellier, France
- Université de Perpignan Via Domitia, 58 Avenue Paul Alduy, 66860, Perpignan, France
| | - Bruno Petton
- Ifremer, LEMAR UMR 6539, UBO, CNRS, IRD, Ifremer, 11 Presqu'île du Vivier, 29840, Argenton-en-Landunvez, France
| | - Jean-Michel Escoubas
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, CC080, 34095, Montpellier, France
- Université de Perpignan Via Domitia, 58 Avenue Paul Alduy, 66860, Perpignan, France
| | - Lionel Dégremont
- Ifremer, SG2M, LGPMM, Avenue du Mus de Loup, 17930, La Tremblade, France
| | - Yannick Gueguen
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, CC080, 34095, Montpellier, France
- Université de Perpignan Via Domitia, 58 Avenue Paul Alduy, 66860, Perpignan, France
- CNRS, Ifremer, IRD, MARBEC, Univ Montpellier, Sète, France
| | - Delphine Destoumieux-Garzόn
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, CC080, 34095, Montpellier, France
- Université de Perpignan Via Domitia, 58 Avenue Paul Alduy, 66860, Perpignan, France
| | - Annick Jacq
- CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, 91198, Gif-Sur-Yvette, France.
| | - Guillaume Mitta
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, CC080, 34095, Montpellier, France.
- Université de Perpignan Via Domitia, 58 Avenue Paul Alduy, 66860, Perpignan, France.
- Ifremer, IRD, ILM, Université de Polynésie Française, UMR 241, Vairao, French Polynesia.
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3
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Picot S, Faury N, Pelletier C, Arzul I, Chollet B, Dégremont L, Renault T, Morga B. Monitoring Autophagy at Cellular and Molecular Level in Crassostrea gigas During an Experimental Ostreid Herpesvirus 1 (OsHV-1) Infection. Front Cell Infect Microbiol 2022; 12:858311. [PMID: 35444958 PMCID: PMC9014014 DOI: 10.3389/fcimb.2022.858311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 03/01/2022] [Indexed: 12/03/2022] Open
Abstract
Mortality outbreaks of young Pacific oysters, Crassostrea gigas, have seriously affected the oyster-farming economy in several countries around the world. Although the causes of these mortality outbreaks appear complex, a viral agent has been identified as the main factor: a herpesvirus called ostreid herpesvirus 1 (OsHV-1). Autophagy is an important degradation pathway involved in the response to several pathologies including viral diseases. In C. gigas, recent studies indicate that this pathway is conserved and functional in at least haemocytes and the mantle. Furthermore, an experimental infection in combination with compounds known to inhibit or induce autophagy in mammals revealed that autophagy is involved in the response to OsHV-1 infection. In light of these results, the aim of this study was to determine the role of autophagy in the response of the Pacific oyster to infection by virus OsHV-1. For this purpose, an experimental infection in combination with a modulator of autophagy was performed on Pacific oysters known to have intermediate susceptibility to OsHV-1 infection. In haemolymph and the mantle, the autophagy response was monitored by flow cytometry, western blotting, and real-time PCR. At the same time, viral infection was evaluated by quantifying viral DNA and RNA amounts by real-time PCR. Although the results showed activation of autophagy in haemolymph and the mantle 14 hours post infection (after viral replication was initiated), they were also indicative of different regulatory mechanisms of autophagy in the two tissues, thus supporting an important function of autophagy in the response to virus OsHV-1.
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Affiliation(s)
- Sandy Picot
- Ifremer, ASIM, Adaptation Santé des invertébrés, La Tremblade, France
| | - Nicole Faury
- Ifremer, ASIM, Adaptation Santé des invertébrés, La Tremblade, France
| | - Camille Pelletier
- Ifremer, ASIM, Adaptation Santé des invertébrés, La Tremblade, France
| | - Isabelle Arzul
- Ifremer, ASIM, Adaptation Santé des invertébrés, La Tremblade, France
| | - Bruno Chollet
- Ifremer, ASIM, Adaptation Santé des invertébrés, La Tremblade, France
| | - Lionel Dégremont
- Ifremer, ASIM, Adaptation Santé des invertébrés, La Tremblade, France
| | - Tristan Renault
- Ifremer, Département Ressources Biologiques et Environnement, La Tremblade, France
| | - Benjamin Morga
- Ifremer, ASIM, Adaptation Santé des invertébrés, La Tremblade, France
- *Correspondence: Benjamin Morga,
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Co-occurrence of pathogen assemblages in a keystone species the common cockle Cerastoderma edule on the Irish coast. Parasitology 2022; 148:1665-1679. [PMID: 35060462 PMCID: PMC8564771 DOI: 10.1017/s0031182021001396] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Despite coinfections being recognized as the rule in animal populations, most studies focus on single pathogen systems. Pathogen interaction networks and the drivers of such associations are lacking in disease ecology studies. Common cockle Cerastoderma edule populations are exposed to a great diversity of pathogens, thus making them a good model system to investigate. This study examined the diversity and prevalence of pathogens from different taxonomic levels in wild and fished C. edule on the Irish coast. Potential interactions were tested focussing on abiotic (seawater temperature and salinity) and biotic (cockle size and age, and epiflora on shells) factors. No Microsporidia nor OsHV-1μVar were detected. Single infections with Haplosporidia (37.7%) or Vibrio (25.3%) were more common than two-pathogen coinfected individuals (9.5%), which may more easily succumb to infection. Fished C. edule populations with high cockle densities were more exposed to infections. Higher temperature and presence of epiflora on cockle shells promoted coinfection in warmer months. Low seawater salinity, host condition and proximity to other infected host species influenced coinfection distribution. A positive association between two Minchinia spp. was observed, most likely due to their different pathogenic effect. Findings highlight the major influence that ecological factors have on pathogen interactions and host–pathogen interplay.
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5
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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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6
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Vanhuysse C, Normand J, Lepoittevin M, Orvain F. Changes in benthic macrofauna in oyster parks during an OsHV-1 μVar oyster spat mortality outbreak. MARINE POLLUTION BULLETIN 2021; 166:112239. [PMID: 33744802 DOI: 10.1016/j.marpolbul.2021.112239] [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: 10/31/2019] [Revised: 02/27/2021] [Accepted: 03/01/2021] [Indexed: 06/12/2023]
Abstract
In intertidal areas, oyster farming creates a crosshatching pattern between oyster tables and aisles. Tables provide a refuge from the current and solar irradiance and the oysters facilitate the accumulation of OM, thereby structuring the spatial organization of the associated macrozoobenthic community at mesoscale. The aim of this study was to describe the quality of the oyster table environment at small scale and the response of the macrozoobenthic community to OsHV-1 μvar oyster mortality. The species assemblage was dominated by Golfingia vulgaris, Tubificoides benedii, Capitella capitata and Scoloplos armiger. The table habitat appeared to be in a bad ecological state throughout the 2-month survey (May and June 2017), whereas in the aisle, eutrophication occurred lately and was clearly related to be due to the massive stranding of dead seaweed at the end of the survey (in early July). So, this disturbance of the species assemblage seemed to occur in two phases: 1) after oyster spat mortality and 2) after seaweed stranding resulted in a bad ecological status, as revealed by macrofaunal indicators. Large quantities of OsHV-1 DNA were also found in some species, including small crabs and amphipods, one week after the mortality crisis, but there is no apparent virus reservoir found in the benthic species.
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Affiliation(s)
- Charles Vanhuysse
- BOREA - Biologie des ORganismes et Ecosystèmes Aquatiques MNHN, UPMC, UCN, CNRS-8207, IRD-207 UFR Sciences, Université de Caen Normandie, Esplanade de la Paix - CS, 14032 CAEN Cedex 5, France.
| | - Julien Normand
- Ifremer, Laboratoire Environnement Ressources de Normandie, Avenue du Général de Gaulle, 14 520 Port en Bessin, France
| | - Mélanie Lepoittevin
- BOREA - Biologie des ORganismes et Ecosystèmes Aquatiques MNHN, UPMC, UCN, CNRS-8207, IRD-207 UFR Sciences, Université de Caen Normandie, Esplanade de la Paix - CS, 14032 CAEN Cedex 5, France
| | - Francis Orvain
- BOREA - Biologie des ORganismes et Ecosystèmes Aquatiques MNHN, UPMC, UCN, CNRS-8207, IRD-207 UFR Sciences, Université de Caen Normandie, Esplanade de la Paix - CS, 14032 CAEN Cedex 5, France.
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7
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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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8
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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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9
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Bookelaar B, Lynch SA, Culloty SC. Host plasticity supports spread of an aquaculture introduced virus to an ecosystem engineer. Parasit Vectors 2020; 13:498. [PMID: 33004060 PMCID: PMC7528252 DOI: 10.1186/s13071-020-04373-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 09/20/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The common cockle Cerastoderma edule plays an important ecological role in the marine ecosystem both as an infaunal engineer (reef forming and bioturbation) and a food source for protected bird species in its European range. Cockle beds are found in close proximity to aquaculture and fisheries operations, which can be "hot spots" for infectious agents including viruses and bacteria. Ostreid herpesvirus-1 microVar (OsHV-1 μVar) has spread to many Pacific oyster Crassostrea gigas culture sites globally, where it has been associated with significant mortalities in this cultured bivalve. Knowledge on the impact of the virus on the wider ecosystem, is limited. As the likelihood of released virus dispersing into the wider aquatic ecosystem is high, the plasticity of the virus and the susceptibility of C. edule to act as hosts or carriers is unknown. METHODS In this study, wild C. edule were sampled biweekly at two C. gigas culture sites over a four-month period during the summer when OsHV-1 μVar prevalence is at its highest in oysters. C. edule were screened for the virus molecularly (PCR, qPCR and Sanger sequencing) and visually (in situ hybridisation (ISH)). The cockle's ability to act as a carrier and transmit OsHV-1 μVar to the oyster host at a temperature of 14 ℃, when the virus is considered to be dormant until water temperatures exceed 16 ℃, was also assessed in laboratory transmission trials. RESULTS The results demonstrated that OsHV-1 μVar was detected in all C. edule size/age cohorts, at both culture sites. In the laboratory, viral transmission was effected from cockles to naïve oysters for the first time, five days post-exposure. The laboratory study also demonstrated that OsHV-1 μVar was active and was successfully transmitted from the C. edule at lower temperatures. CONCLUSIONS This study demonstrates that OsHV-1 μVar has the plasticity to infect the keystone species C. edule and highlights the possible trophic transmission of the virus from cockles to their mobile top predators. This scenario would have important implications, as a greater geographical range expansion of this significant pathogen via migratory bird species may have an impact on other species that reside in bird habitats most of which are special areas of conservation.
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Affiliation(s)
- Babette Bookelaar
- School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland.,Aquaculture and Fisheries Development Centre and Environmental Research Institute, University College Cork, Cork, Ireland
| | - Sharon A Lynch
- School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland. .,Aquaculture and Fisheries Development Centre and Environmental Research Institute, University College Cork, Cork, Ireland.
| | - Sarah C Culloty
- School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland.,Aquaculture and Fisheries Development Centre and Environmental Research Institute, University College Cork, Cork, Ireland.,MaREI Centre, Environmental Research Institute, University College Cork, Cork, Ireland
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10
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Mendes AF, Goncalves P, Serrano-Solis V, Silva PMD. Identification of candidate microRNAs from Ostreid herpesvirus-1 (OsHV-1) and their potential role in the infection of Pacific oysters (Crassostrea gigas). Mol Immunol 2020; 126:153-164. [PMID: 32853878 DOI: 10.1016/j.molimm.2020.08.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 07/31/2020] [Accepted: 08/06/2020] [Indexed: 12/21/2022]
Abstract
Oyster production is an economic activity of great interest worldwide. Recently, oysters have been suffering significant mortalities from OsHV-1infection, which has resulted in substantial economic loses in several countries around the world. Understanding viral pathogenicity mechanisms is of central importance for the establishment of disease control measures. Thus, the present work aimed to identify and characterize miRNAs from OsHV-1 as well as to predict their target transcripts in the virus and the host. OsHV-1 genome was used for the in silico discovery of pre-miRNAs. Subsequently, viral and host target transcripts of the OsHV-1 miRNAs were predicted according to the base pairing interaction between mature miRNAs and mRNA 3' untranslated regions (UTRs). Six unique pre-miRNAs were found in different regions of the viral genome, ranging in length from 85 to 172 nucleotides. A complex network of self-regulation of viral gene expression mediated by the miRNAs was identified. These sequences also seem to have a broad ability to regulate the expression of host immune-related genes, especially those associated with pathogen recognition. Our results suggest that OsHV-1 encodes miRNAs with important functions in the infection process, inducing self-regulation of viral transcripts, as well as affecting the regulation of Pacific oyster transcripts related to immunity. Understanding the molecular basis of host-pathogen interactions can help mitigate the recurrent events of oyster mass mortalities by OsHV-1 observed worldwide.
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Affiliation(s)
- Andrei Félix Mendes
- Laboratório de Imunologia e Patologia de Invertebrados (LABIPI), Departamento de Biologia Molecular, Universidade Federal da Paraíba (UFPB), 58051-900, João Pessoa, Paraíba, Brazil
| | - Priscila Goncalves
- Environment and Sustainability Institute, University of Exeter, Penryn, Cornwall, TR10 9FE, UK
| | - Victor Serrano-Solis
- Laboratório de Imunologia e Patologia de Invertebrados (LABIPI), Departamento de Biologia Molecular, Universidade Federal da Paraíba (UFPB), 58051-900, João Pessoa, Paraíba, Brazil
| | - Patricia Mirella da Silva
- Laboratório de Imunologia e Patologia de Invertebrados (LABIPI), Departamento de Biologia Molecular, Universidade Federal da Paraíba (UFPB), 58051-900, João Pessoa, Paraíba, Brazil.
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11
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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: 13] [Impact Index Per Article: 3.3] [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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12
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Soon TK, Zheng H. Climate Change and Bivalve Mass Mortality in Temperate Regions. REVIEWS OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2020; 251:109-129. [PMID: 31289937 DOI: 10.1007/398_2019_31] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
One of the fastest-growing global food sectors is the bivalve aquaculture industry. Bivalves particularly oysters, mussels and clams are important sources of animal protein (Tan and Ransangan 2016a, b). Bivalve aquaculture represents 14-16% of the average per capita animal protein for 1.5 billion people and supports over 200,000 livelihoods, mostly in developing countries (FAO 2018). Most of the bivalves produced around the world (89%) are from aquaculture (FAO 2016). To date, mollusc aquaculture have accounted for 21.42% (17.14 million tonnes) of the total aquaculture production, with Asia being the largest contributor (92.27%) (FAO 2018).
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Affiliation(s)
- Tan Kar Soon
- Key Laboratory of Marine Biotechnology of Guangdong Province, Shantou University, Shantou, China
| | - Huaiping Zheng
- Key Laboratory of Marine Biotechnology of Guangdong Province, Shantou University, Shantou, China.
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13
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Delisle L, Pauletto M, Vidal-Dupiol J, Petton B, Bargelloni L, Montagnani C, Pernet F, Corporeau C, Fleury E. High temperature induces transcriptomic changes in Crassostrea gigas that hinders progress of Ostreid herpesvirus (OsHV-1) and promotes survival. J Exp Biol 2020; 223:jeb.226233. [PMID: 34005719 PMCID: PMC7578350 DOI: 10.1242/jeb.226233] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 08/07/2020] [Indexed: 12/30/2022]
Abstract
Among all the environmental factors, seawater temperature plays a decisive role in triggering marine diseases. Like fever in vertebrates, high seawater temperature could modulate the host response to the pathogens in ectothermic animals. In France, massive mortality of Pacific oysters Crassostrea gigas caused by the ostreid herpesvirus 1 (OsHV-1) is markedly reduced when temperatures exceed 24°C in the field. In the present study we assess how high temperature influences the host response to the pathogen by comparing transcriptomes (RNA-sequencing) during the course of experimental infection at 21°C (reference) and 29°C. We show that high temperature induced host physiological processes that are unfavorable to the viral infection. Temperature influenced the expression of transcripts related to the immune process and increased the transcription of genes related to apoptotic process, synaptic signaling, and protein processes at 29°C. Concomitantly, the expression of genes associated to catabolism, metabolites transport, macromolecules synthesis and cell growth remained low since the first stage of infection at 29°C. Moreover, viral entry into the host might have been limited at 29°C by changes in extracellular matrix composition and protein abundance. Overall, these results provide new insights into how environmental factors modulate the host-pathogen interactions.
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Affiliation(s)
- Lizenn Delisle
- Ifremer, Université de Brest, CNRS, IRD, LEMAR, F-29280 Plouzané, France
- Cawthron Institute, 98 Halifax Street East, Private Bag 2, Nelson 7042, New Zealand
| | - Marianna Pauletto
- Department of Comparative Biomedicine and Food Science, University of Padova, Viale dell'Università 16, 35020 Legnaro, Padova, Italy
| | - Jeremie Vidal-Dupiol
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan, Via Domitia, F-34095 Montpellier, France
| | - Bruno Petton
- Ifremer, Université de Brest, CNRS, IRD, LEMAR, F-29280 Plouzané, France
| | - Luca Bargelloni
- Department of Comparative Biomedicine and Food Science, University of Padova, Viale dell'Università 16, 35020 Legnaro, Padova, Italy
| | - Caroline Montagnani
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan, Via Domitia, F-34095 Montpellier, France
| | - Fabrice Pernet
- Ifremer, Université de Brest, CNRS, IRD, LEMAR, F-29280 Plouzané, France
| | | | - Elodie Fleury
- Ifremer, Université de Brest, CNRS, IRD, LEMAR, F-29280 Plouzané, France
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14
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Carvalho-Saucedo L, Racotta IS, Guerra-Danielsen C. Pathological changes by Eosinophilic Rickettsia-like organism in Japanese oyster, Crassostrea gigas. J Invertebr Pathol 2019; 167:107248. [PMID: 31525353 DOI: 10.1016/j.jip.2019.107248] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 09/12/2019] [Accepted: 09/13/2019] [Indexed: 11/28/2022]
Abstract
Rickettsia infection in adult Japanese oysters (Crassostrea gigas) was observed in 2015 at San Ignacio Lagoon, Baja California Sur, Mexico and characterized using molecular tools. In the present study, the degree of infection by Eosinophilic Rickettsia-Like Organism (E-RLO), characterized by intracellular inclusions in gill, mantle, labial palps, digestive tract and gonadal ducts, was evaluated using histological methods and was associated with visible injuries on body surface, such as blisters, shell damage and necrosis. Most of the oysters (92.2%) had some type of observable symptoms; 90.2% of all oysters had blisters in the mantle, and all oysters presented with E-RLO in the epithelia of at least one of the analyzed tissues (gills, labial palps, mantle, gonadal ducts and digestive tract). The highest intensity of infection (percent of E-RLO coverage) was observed in the labial palps (18.6%) and the lowest in digestive tract (2.6% of the examined tissue). Oysters with external injuries had higher infection intensities than the oysters without external injuries. Considering the clinical signs (observable symptoms and histological findings), we propose three infective stages of E-RLO disease development, a scale that could be used for early detection.
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Affiliation(s)
- Liliana Carvalho-Saucedo
- Centro de Investigaciones Biológicas del Noroeste, Instituto Politécnico Nacional 195, Playa Palo de Santa Rita Sur, La Paz, B.C.S. C.P. 23096, Mexico.
| | - Ilie S Racotta
- Centro de Investigaciones Biológicas del Noroeste, Instituto Politécnico Nacional 195, Playa Palo de Santa Rita Sur, La Paz, B.C.S. C.P. 23096, Mexico.
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15
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Petton B, de Lorgeril J, Mitta G, Daigle G, Pernet F, Alunno-Bruscia M. Fine-scale temporal dynamics of herpes virus and vibrios in seawater during a polymicrobial infection in the Pacific oyster Crassostrea gigas. DISEASES OF AQUATIC ORGANISMS 2019; 135:97-106. [PMID: 31342911 DOI: 10.3354/dao03384] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The Pacific oyster Crassostrea gigas is currently being impacted by a polymicrobial disease that involves early viral infection by ostreid herpesvirus-1 (OsHV-1) followed by a secondary bacterial infection leading to death. A widely used method of inducing infection consists of placing specific pathogen-free oysters ('recipients') in cohabitation in the laboratory with diseased oysters that were naturally infected in the field ('donors'). With this method, we evaluated the temporal dynamics of pathogen release in seawater and the cohabitation time necessary for disease transmission and expression. We showed that OsHV-1 and Vibrio spp. in the seawater peaked concomitantly during the first 48 h and decreased thereafter. We found that 1.5 h of cohabitation with donors was enough time to transmit pathogens to recipients and to induce mortality later, reflecting the highly contagious nature of the disease. Finally, mortality of recipients was associated with increasing cohabitation time with donors until reaching a plateau at 20%. This reflects the cumulative effect of exposure to pathogens. The optimal cohabitation time was 5-6 d, the mortality of recipients occurring 1-2 d earlier.
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Affiliation(s)
- Bruno Petton
- Ifremer, LEMAR UMR 6539 (Université de Bretagne Occidentale, CNRS, IRD, Ifremer), 11 presqu'île du Vivier, 29840 Argenton-en-Landunvez, France
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16
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Figueras A, Moreira R, Sendra M, Novoa B. Genomics and immunity of the Mediterranean mussel Mytilus galloprovincialis in a changing environment. FISH & SHELLFISH IMMUNOLOGY 2019; 90:440-445. [PMID: 31048040 DOI: 10.1016/j.fsi.2019.04.064] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The Mediterranean mussel (Mytilus galloprovincialis) is a marine invasive species cultured all over the world. Mussels are an appreciated resource in local aquaculture enterprises because of their robust production and resilience that translates into a reliable economic value. So far, no massive mortalities have been reported in natural or cultured populations of this species. In the last years, the knowledge about its immune system has greatly improved but there are still many questions to be answered. One of them is why mussels, with their high filtering activity, are able to be exposed to a high number of potential pathogens without getting infected and without developing an elevated inflammatory response. The sequencing of the mussel genome has revealed a very complex organization with high heterozygosity, abundance of repetitive sequences and extreme intraspecific sequence diversity among individuals, mainly in immune related genes. Among those genes, antimicrobial peptides are the most expressed gene families in mussels, highly polymorphic and with antimicrobial effect against molluscs pathogens, but also against pathogens of lower vertebrates and humans. The combination of a complex genome with the adaptation of mussel immune system to a changing environment could explain this high variability, not only in immune-related genes, but also in the functional response among individuals sampled in the same location and date.
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Affiliation(s)
- Antonio Figueras
- Institute of Marine Research (IIM), National Research Council (CSIC), Eduardo Cabello 6, 36208, Vigo, Spain.
| | - Rebeca Moreira
- Institute of Marine Research (IIM), National Research Council (CSIC), Eduardo Cabello 6, 36208, Vigo, Spain
| | - Marta Sendra
- Institute of Marine Research (IIM), National Research Council (CSIC), Eduardo Cabello 6, 36208, Vigo, Spain
| | - Beatriz Novoa
- Institute of Marine Research (IIM), National Research Council (CSIC), Eduardo Cabello 6, 36208, Vigo, Spain
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17
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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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18
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de Lorgeril J, Lucasson A, Petton B, Toulza E, Montagnani C, Clerissi C, Vidal-Dupiol J, Chaparro C, Galinier R, Escoubas JM, Haffner P, Dégremont L, Charrière GM, Lafont M, Delort A, Vergnes A, Chiarello M, Faury N, Rubio T, Leroy MA, Pérignon A, Régler D, Morga B, Alunno-Bruscia M, Boudry P, Le Roux F, Destoumieux-Garzόn D, Gueguen Y, Mitta G. Immune-suppression by OsHV-1 viral infection causes fatal bacteraemia in Pacific oysters. Nat Commun 2018; 9:4215. [PMID: 30310074 PMCID: PMC6182001 DOI: 10.1038/s41467-018-06659-3] [Citation(s) in RCA: 132] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 09/18/2018] [Indexed: 11/09/2022] Open
Abstract
Infectious diseases are mostly explored using reductionist approaches despite repeated evidence showing them to be strongly influenced by numerous interacting host and environmental factors. Many diseases with a complex aetiology therefore remain misunderstood. By developing a holistic approach to tackle the complexity of interactions, we decipher the complex intra-host interactions underlying Pacific oyster mortality syndrome affecting juveniles of Crassostrea gigas, the main oyster species exploited worldwide. Using experimental infections reproducing the natural route of infection and combining thorough molecular analyses of oyster families with contrasted susceptibilities, we demonstrate that the disease is caused by multiple infection with an initial and necessary step of infection of oyster haemocytes by the Ostreid herpesvirus OsHV-1 µVar. Viral replication leads to the host entering an immune-compromised state, evolving towards subsequent bacteraemia by opportunistic bacteria. We propose the application of our integrative approach to decipher other multifactorial diseases that affect non-model species worldwide. Pacific oyster mortality syndrome is a poorly understood cause of mortality in commercially important oyster species. Here, the authors use multiple infection experiments to show that the syndrome is caused by sequential infection by herpesvirus and opportunistic bacteria.
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Affiliation(s)
- Julien de Lorgeril
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, 34095, Montpellier, France
| | - Aude Lucasson
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, 34095, Montpellier, France
| | - Bruno Petton
- LEMAR UMR 6539, UBO/CNRS/IRD/Ifremer, 11 presqu'île du vivier, 29840, Argenton-en-Landunvez, France
| | - Eve Toulza
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, 34095, Montpellier, France
| | - Caroline Montagnani
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, 34095, Montpellier, France
| | - Camille Clerissi
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, 34095, Montpellier, France
| | - Jeremie Vidal-Dupiol
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, 34095, Montpellier, France
| | - Cristian Chaparro
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, 34095, Montpellier, France
| | - Richard Galinier
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, 34095, Montpellier, France
| | - Jean-Michel Escoubas
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, 34095, Montpellier, France
| | - Philippe Haffner
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, 34095, Montpellier, France
| | - Lionel Dégremont
- Laboratoire de Génétique et Pathologie des Mollusques Marins, Ifremer, Avenue du Mus de Loup, 17930, La Tremblade, France
| | - Guillaume M Charrière
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, 34095, Montpellier, France
| | - Maxime Lafont
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, 34095, Montpellier, France
| | - Abigaïl Delort
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, 34095, Montpellier, France
| | - Agnès Vergnes
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, 34095, Montpellier, France
| | - Marlène Chiarello
- Marine Biodiversity, Exploitation and Conservation (MARBEC), Université de Montpellier, CNRS, IRD, Ifremer, Place E. Bataillon, 34095, Montpellier, France
| | - Nicole Faury
- Laboratoire de Génétique et Pathologie des Mollusques Marins, Ifremer, Avenue du Mus de Loup, 17930, La Tremblade, France
| | - Tristan Rubio
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, 34095, Montpellier, France
| | - Marc A Leroy
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, 34095, Montpellier, France
| | - Adeline Pérignon
- CRCM, Comité de la Conchyliculture de Méditerranée, Quai Baptiste Guitard, 34140, Mèze, France
| | - Denis Régler
- CRCM, Comité de la Conchyliculture de Méditerranée, Quai Baptiste Guitard, 34140, Mèze, France
| | - Benjamin Morga
- Laboratoire de Génétique et Pathologie des Mollusques Marins, Ifremer, Avenue du Mus de Loup, 17930, La Tremblade, France
| | - Marianne Alunno-Bruscia
- LEMAR UMR 6539, UBO/CNRS/IRD/Ifremer, 11 presqu'île du vivier, 29840, Argenton-en-Landunvez, France
| | - Pierre Boudry
- LEMAR UMR6539, CNRS/UBO/IRD/Ifremer, ZI pointe du diable, CS 10070, F-29280, Plouzané, France
| | - Frédérique Le Roux
- Sorbonne Universités, UPMC Paris 06, CNRS, UMR 8227, LBI2M, Ifremer, Station Biologique de Roscoff, CS 90074, F-29680, Roscoff, France
| | - Delphine Destoumieux-Garzόn
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, 34095, Montpellier, France
| | - Yannick Gueguen
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, 34095, Montpellier, France.
| | - Guillaume Mitta
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Place E. Bataillon, 34095, Montpellier, France.
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Bookelaar BE, O'Reilly AJ, Lynch SA, Culloty SC. Role of the intertidal predatory shore crab Carcinus maenas in transmission dynamics of ostreid herpesvirus-1 microvariant. DISEASES OF AQUATIC ORGANISMS 2018; 130:221-233. [PMID: 30259874 DOI: 10.3354/dao03264] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Ostreid herpesvirus-1 microVar (OsHV-1 µVar) has been responsible for significant mortalities globally in the Pacific oyster Crassostrea gigas. While the impact of this virus on the Pacific oyster has been significant, this pathogen may have wider ecosystem consequences. It has not been definitively determined how the virus is sustaining itself in the marine environment and whether other species are susceptible. The shore crab Carcinus maenas is a mobile predator and scavenger of C. gigas, commonly found at Pacific oyster culture sites. The aim of this study was to investigate the role of the crab in viral maintenance and transmission to the Pacific oyster. A field trial took place over 1 summer at different shore heights at 2 Irish Pacific oyster culture sites that are endemic for OsHV-1 µVar. Infection of OsHV-1 µVar in tissues of C. maenas at both shore heights of both sites was detected by polymerase chain reaction (PCR), quantitative PCR (qPCR), in situ hybridization and direct Sanger sequencing. In addition, a laboratory trial demonstrated that transmission of the virus could occur to naïve C. gigas within 4 d, from C. maenas previously exposed to the virus in the wild. These findings provide some insight into the possibility that the virus can be transmitted through marine food webs. The results also suggest viral plasticity in the hosts required by the virus and potential impacts on a range of crustacean species with wider ecosystem impacts if transmission to other species occurs.
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Affiliation(s)
- B E Bookelaar
- Aquaculture and Fisheries Development Centre, School of Biological, Earth and Environmental Sciences & Environmental Research Institute, University College Cork, Cork, Ireland
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20
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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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21
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The role of the mussel Mytilus spp. in the transmission of ostreid herpesvirus-1 microVar. Parasitology 2017; 145:1095-1104. [PMID: 29262879 DOI: 10.1017/s0031182017002244] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The Pacific oyster Crassostrea gigas contributes significantly to global aquaculture; however, C. gigas culture has been affected by ostreid herpesvirus-1 (OsHV-1) and variants. The dynamics of how the virus maintains itself at culture sites is unclear and the role of carriers, reservoirs or hosts is unknown. Both wild and cultured mussels Mytilus spp. (Mytilus edulis, Mytilus galloprovincialis and hybrids) are commonly found at C. gigas culture sites. The objective of this study was to investigate if Mytilus spp. can harbour the virus and if viral transmission can occur between mussels and oysters. Mytilus spp. living at oyster trestles, 400-500 m higher up the shore from the trestles and up to 26 km at non-culture sites were screened for OsHV-1 and variants by all the World Organization for Animal Health (OIE) recommended diagnostic methods including polymerase chain reaction (PCR), quantitative PCR (qPCR), histology, in situ hybridization and confirmation using direct sequencing. The particular primers that target OsHV-1 and variants, including OsHV-1 microVar (μVar), were used in the PCR and qPCR. OsHV-1 μVar was detected in wild Mytilus spp. at C. gigas culture sites and more significantly the virus was detected in mussels at non-culture sites. Cohabitation of exposed wild mussels and naïve C. gigas resulted in viral transmission after 14 days, under an elevated temperature regime. These results indicate that mussels can harbour OsHV-1 μVar; however, the impact of OsHV-1 μVar on Mytilus spp. requires further investigation.
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Complete genome sequence of Ostreid herpesvirus type 1 µVar isolated during mortality events in the Pacific oyster Crassostrea gigas in France and Ireland. Virology 2017; 509:239-251. [PMID: 28672223 DOI: 10.1016/j.virol.2017.06.027] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 06/14/2017] [Accepted: 06/23/2017] [Indexed: 12/13/2022]
Abstract
Infections with Ostreid herpesvirus 1 (OsHV-1) microvariants in young Pacific oysters are associated with massive mortality events and significant economic losses. Previous studies, focusing on few regions of the genome, have revealed the genomic diversity of these genotypes with respect to the reference type. We used a NGS process to sequence the whole genome of the OsHV-1 µVar in infected individuals, collected during mortality events in France and Ireland. The final genome length of OsHV-1 µVar was approximately 205kbp, shorter than the reference genotype and the overall genome organisation resembled herpes simplex viruses. 94.4% similarity was observed with the OsHV-1 reference genotype. Large indels, including five deletions and three insertions were found to induce the loss and the addition of several ORFs, summed with codon substitutions in 64% of genes shared with the reference type. This diversity raises the question of the exact origin and evolution of OsHV-1 µVar.
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Zannella C, Mosca F, Mariani F, Franci G, Folliero V, Galdiero M, Tiscar PG, Galdiero M. Microbial Diseases of Bivalve Mollusks: Infections, Immunology and Antimicrobial Defense. Mar Drugs 2017. [PMID: 28629124 PMCID: PMC5484132 DOI: 10.3390/md15060182] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
A variety of bivalve mollusks (phylum Mollusca, class Bivalvia) constitute a prominent commodity in fisheries and aquacultures, but are also crucial in order to preserve our ecosystem’s complexity and function. Bivalve mollusks, such as clams, mussels, oysters and scallops, are relevant bred species, and their global farming maintains a high incremental annual growth rate, representing a considerable proportion of the overall fishery activities. Bivalve mollusks are filter feeders; therefore by filtering a great quantity of water, they may bioaccumulate in their tissues a high number of microorganisms that can be considered infectious for humans and higher vertebrates. Moreover, since some pathogens are also able to infect bivalve mollusks, they are a threat for the entire mollusk farming industry. In consideration of the leading role in aquaculture and the growing financial importance of bivalve farming, much interest has been recently devoted to investigate the pathogenesis of infectious diseases of these mollusks in order to be prepared for public health emergencies and to avoid dreadful income losses. Several bacterial and viral pathogens will be described herein. Despite the minor complexity of the organization of the immune system of bivalves, compared to mammalian immune systems, a precise description of the different mechanisms that induce its activation and functioning is still missing. In the present review, a substantial consideration will be devoted in outlining the immune responses of bivalves and their repertoire of immune cells. Finally, we will focus on the description of antimicrobial peptides that have been identified and characterized in bivalve mollusks. Their structural and antimicrobial features are also of great interest for the biotechnology sector as antimicrobial templates to combat the increasing antibiotic-resistance of different pathogenic bacteria that plague the human population all over the world.
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Affiliation(s)
- Carla Zannella
- Department of Experimental Medicine-University of Campania "Luigi Vanvitelli", Via Costantinopoli 16, 80138 Napoli, Italy.
| | - Francesco Mosca
- Faculty of Veterinary Medicine, University of Teramo, Piano d'Accio, 64100 Teramo, Italy.
| | - Francesca Mariani
- Faculty of Veterinary Medicine, University of Teramo, Piano d'Accio, 64100 Teramo, Italy.
| | - Gianluigi Franci
- Department of Experimental Medicine-University of Campania "Luigi Vanvitelli", Via Costantinopoli 16, 80138 Napoli, Italy.
| | - Veronica Folliero
- Department of Experimental Medicine-University of Campania "Luigi Vanvitelli", Via Costantinopoli 16, 80138 Napoli, Italy.
| | - Marilena Galdiero
- Department of Experimental Medicine-University of Campania "Luigi Vanvitelli", Via Costantinopoli 16, 80138 Napoli, Italy.
| | - Pietro Giorgio Tiscar
- Faculty of Veterinary Medicine, University of Teramo, Piano d'Accio, 64100 Teramo, Italy.
| | - Massimiliano Galdiero
- Department of Experimental Medicine-University of Campania "Luigi Vanvitelli", Via Costantinopoli 16, 80138 Napoli, Italy.
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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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25
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Vincent-Hubert F, Morga B, Renault T, Le Guyader F. Adsorption of norovirus and ostreid herpesvirus type 1 to polymer membranes for the development of passive samplers. J Appl Microbiol 2017; 122:1039-1047. [DOI: 10.1111/jam.13394] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 12/20/2016] [Accepted: 01/02/2017] [Indexed: 02/04/2023]
Affiliation(s)
- F. Vincent-Hubert
- Laboratoire de Microbiologie; LSEM/SG2M; Ifremer; Nantes Cedex 03 France
| | - B. Morga
- Laboratoire de Génétique et Pathologie des Mollusques; SG2M Station de La Tremblade; La Tremblade France
| | - T. Renault
- Département Ressources Biologiques et Environnement; Ifremer; Nantes France
| | - F.S. Le Guyader
- Laboratoire de Microbiologie; LSEM/SG2M; Ifremer; Nantes Cedex 03 France
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26
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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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27
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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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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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29
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López-Sanmartín M, López-Fernández JR, Cunha ME, De la Herrán R, Navas JI. Ostreid herpesvirus in wild oysters from the Huelva coast (SW Spain). DISEASES OF AQUATIC ORGANISMS 2016; 120:231-240. [PMID: 27503919 DOI: 10.3354/dao03031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This is the first report of ostreid herpesvirus 1 microvariant (OsHV-1 µVar) infecting natural oyster beds located in Huelva (SW Spain). The virus was detected in 3 oyster species present in the intertidal zone: Crassostrea gigas (Thunberg, 1793), C. angulata (Lamarck, 1819) and, for the first time, in Ostrea stentina Payraudeau, 1826. Oysters were identified by a specific polymerase chain reaction (PCR) and posterior restriction fragment length polymorphism (RFLP) analysis based on cytochrome oxidase I (COI) mitochondrial DNA. Results confirmed that C. angulata still remains the dominant oyster population in SW Spain despite the introduction of C. gigas for cultivation in the late 1970s, and its subsequent naturalization. C. angulata shows a higher haplotype diversity than C. gigas. OsHV-1 virus was detected by PCR with C2/C6 pair primers. Posterior RFLP analyses with the restriction enzyme MfeI were done in order to reveal the OsHV-1 µVar. Detections were confirmed by DNA sequencing, and infections were evidenced by in situ hybridization in C. gigas, C. angulata and O. stentina samples. The prevalence was similar among the 3 oyster species but varied between sampling locations, being higher in areas with greater harvesting activities. OsHV-1 µVar accounted for 93% of all OsHV-1 detected.
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Affiliation(s)
- M López-Sanmartín
- IFAPA Centro Agua del Pino, Consejería de Agricultura, Pesca y Desarrollo Rural, Junta de Andalucía, Ctra. El Rompido-Punta Umbría Km 3.8, 21459 Cartaya, Huelva, Spain
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Burioli EAV, Prearo M, Riina MV, Bona MC, Fioravanti ML, Arcangeli G, Houssin M. Ostreid herpesvirus type 1 genomic diversity in wild populations of Pacific oyster Crassostrea gigas from Italian coasts. J Invertebr Pathol 2016; 137:71-83. [PMID: 27234424 DOI: 10.1016/j.jip.2016.05.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 05/19/2016] [Accepted: 05/21/2016] [Indexed: 11/26/2022]
Abstract
Ostreid herpesvirus 1 (OsHV-1) is a significant pathogen affecting the young Pacific oyster Crassostrea gigas, worldwide. A new variant, OsHV-1 μVar, has been associated with recurrent mortality events in Europe since 2008. Epidemiological data collection is key for global risk assessment; however little is known about health status and genotypes present in European wild oyster beds. Most studies to date have involved only cultivated individuals during mortality events, and reported low genotype diversity. With this study, conducted along the Italian coasts, we investigated for the first time the presence of OsHV-1 in European natural oyster beds. Analysis of three genomic regions revealed the presence of at least nine different genotypes, including two variants close to the OsHV-1 reference, known since the early 1990s but with no European record reported since 2010, and highlights relevant genotype diversity in natural environment. Phylogenetic analysis distinguished two distinct clusters and geographical distribution of genotypes, with the exception of a variant very closely related to the μVar, which appeared the single genotype present in all the Adriatic sites. Interestingly, these wild symptom free populations could represent, in Europe, an accessible alternative to the import of OsHV-1-resistant oyster strains from the East Pacific, the native area of C. gigas, avoiding the high-risk of non-native marine species and new pathogen introductions.
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Affiliation(s)
- E A V Burioli
- Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Torino, Italy; Department of Veterinary Medical Sciences, Alma Mater Studiorum, Università di Bologna, Ozzano dell'Emilia, BO, Italy.
| | - M Prearo
- Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Torino, Italy
| | - M V Riina
- Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Torino, Italy
| | - M C Bona
- Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Torino, Italy
| | - M L Fioravanti
- Department of Veterinary Medical Sciences, Alma Mater Studiorum, Università di Bologna, Ozzano dell'Emilia, BO, Italy
| | - G Arcangeli
- Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, PD, Italy
| | - M Houssin
- Laboratoire Frank Duncombe LABEO, Caen, France
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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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Chen IW, Chang PH, Chen MS, Renault T, Chen MM, Kuo ST, Cheng CH. EXPLORING THE CHRONIC MORTALITY AFFECTING ABALONES IN TAIWAN: DIFFERENTIATION OF ABALONE HERPESVIRUS-ASSOCIATED ACUTE INFECTION FROM CHRONIC MORTALITY BY PCR AND IN SITU HYBRIDIZATION AND HISTOPATHOLOGY. ACTA ACUST UNITED AC 2016. [DOI: 10.1142/s1682648515500237] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Abalone herpesvirus (AbHV) infection of cultured abalones Haliotis diversicolor supertexta induced acute high mortality in 2003. Years later, sporadic mortality was noted for an extended period of months, resulting in high cumulative mortality. Moribund abalones were analyzed using PCR, in situ hybridization, and histopathology, because thus far no viral particles have been observed by transmission electron microscopy. PCR using 20 primer sets, specifically designed from sequences of acute AbHV infection, failed to amplify any products from abalones suffering from chronic mortality. Subsequently, a 1406-bp sequence was amplified from chronic moribund abalones, and this sequence showed a 92% (553 bp/602 bp) homology with the gene of an AbHV Taiwan isolate (NCBI serial no. KF537536.1), suggestive of an AbHV pathotype. Histopathology of AbHV pathotype infection showed hemocyte infiltration in the lamina propia of the digestive tract, and hemocytes of various stages were evident, as well as the loss of seminal tubules in the gonad. In situ hybridization revealed that in AbHV infection, positive signals were restricted to the neural ganglia, while in AbHV pathotype infection, positive signals were observed only in the hemocytes. It appeared that the tropism of AbHV shifted from mainly neurotropic in AbHV infection to mainly hemocytotropic in abalone suffering from chronic mortality. Abalone shriveling syndrome-associated virus co-infection was detected in some of AbHV pathotype infection events. Further studies are needed to better understand the pathogenesis of AbHV pathotype affecting H. diversicolor in Taiwan.
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Affiliation(s)
- I-Wen Chen
- Institute of Comparative and Molecular Pathobiology, School of Veterinary Medicine, National Taiwan University, Taipei, Taiwan
| | - Pen-Heng Chang
- Institute of Comparative and Molecular Pathobiology, School of Veterinary Medicine, National Taiwan University, Taipei, Taiwan
| | - Min-Shou Chen
- Institute of Comparative and Molecular Pathobiology, School of Veterinary Medicine, National Taiwan University, Taipei, Taiwan
- Tzu Chi College of Technology, Hualien, Taiwan
| | - Tristan Renault
- Ifremer, Unité Santé Génétique et Microbiologie des Mollusques (SG2M), Laboratoire de Génétique et Pathologie des Mollusques Marins (LGPMM), 17390 La Tremblade, France
| | - Meei-Mei Chen
- Department of Veterinary Medicine, School of Veterinary Medicine, National Taiwan University, Taipei, Taiwan
| | - Shu-Ting Kuo
- Animal Health Research Institute, Tansui, Taiwan
| | - Chiung-Hsiang Cheng
- Institute of Comparative and Molecular Pathobiology, School of Veterinary Medicine, National Taiwan University, Taipei, Taiwan
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López Sanmartín M, Power DM, de la Herrán R, Navas JI, Batista FM. Experimental infection of European flat oyster Ostrea edulis with ostreid herpesvirus 1 microvar (OsHV-1μvar): Mortality, viral load and detection of viral transcripts by in situ hybridization. Virus Res 2016; 217:55-62. [PMID: 26945849 DOI: 10.1016/j.virusres.2016.01.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 01/29/2016] [Indexed: 11/29/2022]
Abstract
Ostreid herpesvirus 1 (OsHV-1) infections have been reported in several bivalve species. Mortality of Pacific oyster Crassostrea gigas spat has increased considerably in Europe since 2008 linked to the spread of a variant of OsHV-1 called μvar. In the present study we demonstrated that O. edulis juveniles can be infected by OsHV-1μvar when administered as an intramuscular injection. Mortality in the oysters injected with OsHV-1μvar was first detected 4 days after injection and reached 25% mortality at day 10. Moreover, the high viral load observed and the detection of viral transcripts by in situ hybridization in several tissues of dying oysters suggested that OsHV-1μvar was the cause of mortality in the O. edulis juveniles. This is therefore the first study to provide evidence about the pathogenicity of OsHV-1μvar in a species that does not belong to the Crassostrea genus. Additionally, we present a novel method to detect OsHV-1 transcripts in infected individuals' using in situ hybridization.
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Affiliation(s)
- Monserrat López Sanmartín
- Instituto de Investigación y Formación Agraria y Pesquera (IFAPA), Centro Agua del Pino, Junta de Andalucía, Ctra. El Rompido-Punta Umbría, km 4, 21459 Cartaya, Spain.
| | - Deborah M Power
- Centro de Ciências do Mar (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
| | | | - José I Navas
- Instituto de Investigación y Formación Agraria y Pesquera (IFAPA), Centro Agua del Pino, Junta de Andalucía, Ctra. El Rompido-Punta Umbría, km 4, 21459 Cartaya, Spain
| | - Frederico M Batista
- Centro de Ciências do Mar (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; Instituto Português do Mar e da Atmosfera, Divisão de Aquicultura e Valorização, Estação Experimental de Moluscicultura de Tavira, Av. 5 de Outubro, 8700-305 Olhão, Portugal
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Bai C, Gao W, Wang C, Yu T, Zhang T, Qiu Z, Wang Q, Huang J. Identification and characterization of ostreid herpesvirus 1 associated with massive mortalities of Scapharca broughtonii broodstocks in China. DISEASES OF AQUATIC ORGANISMS 2016; 118:65-75. [PMID: 26865236 DOI: 10.3354/dao02958] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In the early summer of 2012 and 2013, mass mortalities of blood ark shell (Scapharca [Anadara] broughtonii), broodstocks were reported in several hatcheries on the coast of northern China. Clinical signs including slow response, gaping valves and pale visceral mass were observed in diseased individuals. In response to these reported mortalities, 238 samples were collected from hatcheries at 6 sites. Microscopic changes including lysed connective tissue, dilation of the digestive tubules, eosinophilic inclusion bodies, nuclear chromatin margination and pyknosis were found in affected animals. Transmission electron microscopy (TEM) revealed herpes-like viral particles within the connective tissue of the mantle. Quantative PCR (qPCR) and nested PCR (nPCR) analysis using primers specific for ostreid herpesvirus 1 (OsHV-1) indicated significant higher prevalence of OsHV-1 DNA in cases associated with mass mortalities than those without mass mortalities (p = 0.0012 for qPCR, p < 0.0001 for nPCR). qPCR also indicated that samples associated with mass mortalities carried high viral DNA loads, while the loads in apparently healthy samples were significantly lower (t = 3.15, df = 92, p = 0.002). Sequence analysis of the C2/C6 region of nPCR products revealed 5 newly described variants, which were closely related to each other. Phylogenetic analysis of the 5 virus variants and 48 virus variants reported in previous studies identified 2 main phylogenetic groups, and the 5 virus variants identified here were allocated to a separate subclade. To our knowledge, this is the first report of mass mortalities of bivalve broodstocks associated with OsHV-1 infection.
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Affiliation(s)
- Changming Bai
- Division of Maricultural Organism Disease Control and Molecular Pathology, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, 106 Nanjing Road, Qingdao 266071, PR China
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Detection of undescribed ostreid herpesvirus 1 (OsHV-1) specimens from Pacific oyster, Crassostrea gigas. J Invertebr Pathol 2015; 132:182-189. [PMID: 26527255 DOI: 10.1016/j.jip.2015.10.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 10/16/2015] [Accepted: 10/20/2015] [Indexed: 11/21/2022]
Abstract
The ostreid herpesvirus 1 (OsHV-1) and variants were implicated in mass mortality affecting the young Pacific cupped oysters, Crassostrea gigas, in European countries and those around the world. From 2008 onwards, oyster mortality had greatly increased on the French coast and was associated with the detection of a new OsHV-1 variant, entitled OsHV-1 μVar. The OsHV-1 μVar is predominant in oysters; however, other OsHV-1 variants have been detected in samples collected during mortality periods or collected out of mortality periods in France, Ireland, Spain, Portugal, Italy, Mexico, United States, South Korea, Australia, and New Zealand. A retrospective study conducted on 1047 OsHV-1 specimens sampled mainly in France between 2009 and 2012, revealed 17 undescribed OsHV-1 variants found in 65 oyster samples. These specimens presented point mutations situated downstream and upstream from the microsatellite area in the C region (ORF 4/5) which were different from the OsHV-1 reference and the OsHV-1 μVar. In the present work, investigation was performed to further characterize these OsHV-1 specimens by sequencing two habitually targeted regions to study genetic polymorphism of the virus: ORF 41/42 and ORF 35-38. An OsHV-1 variant detected in six oyster samples, contained a nucleotide substitution in the C region which impacted the amino acid sequence and might modify the function of the unknown protein encoding by ORF 4. For the ORF 41/42 region, only two specimens presented a synonymous mutation in comparison with the OsHV-1 μVar. All specimens contained the same deletion with the OsHV-1 μVar in ORF 35-38. Then, a phylogenetic analysis based on the C region was performed to investigate the distribution of undescribed specimens among 21 OsHV-1 DNA sequences notified in GenBank and collected from different countries (France, Japan, New Zealand, China, Ireland, and United States) between 1995 and 2012. All analyzed samples and the OsHV-1 μVar were placed in the same group, excepted for a Japan specimen. Our results contribute to improve the description of the genetic diversity of the OsHV-1 and the C region (ORF 4/5) appears to be a better target than ORF 42/42 and 35-38 to distinguish variants between themselves.
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38
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Xia J, Bai C, Wang C, Song X, Huang J. Complete genome sequence of Ostreid herpesvirus-1 associated with mortalities of Scapharca broughtonii broodstocks. Virol J 2015. [PMID: 26209441 PMCID: PMC4514999 DOI: 10.1186/s12985-015-0334-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Background Ostreid herpesvirus-1 (OsHV-1) is the major bivalve pathogen associated with severe mortality events in a wide host range. In the early summer of 2012 and 2013, mass mortalities of blood clam (Scapharca broughtonii) broodstocks associated with a newly described variant of OsHV-1 (OsHV-1-SB) were reported. Methods In this study, the complete genome sequence of the newly described variant was determined through the primer walking approach, and compared with those of the other two OsHV-1 variants. Results OsHV-1-SB genome was found to contain 199, 354 bp nucleotides with 38.5 % G/C content, which is highly similar to those of acute viral necrosis virus (AVNV) and OsHV-1 reference type. A total of 123 open reading frames (ORFs) putatively encoding functional proteins were identified; eight of which were duplicated in the major repeat elements of the genome. The genomic organization of OsHV-1-SB could be represented as TRL-UL-IRL-IRS-US-TRS, which is different from that of OsHV-1 reference type and AVNV due to the deletion of a unique region (X, 1.5Kb) between IRL and IRS. The DNA sequence of OsHV-1-SB is 95.2 % and 97.3 % identical to that of OsHV-1 reference type and AVNV respectively. On the basis of nucleotide sequences of 32 ORFs in OsHV-1-SB and the other nine OsHV-1 variants, results from phylogenetic analysis also demonstrated that OsHV-1-SB is most closely related to AVNV. Conclusions The determination of the genome of OsHV-1 with distinguished epidemiological features will aid in our better understanding of OsHV-1 diversity, and facilitate further research on the origin, evolution, and epidemiology of the virus. Electronic supplementary material The online version of this article (doi:10.1186/s12985-015-0334-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Junyang Xia
- College of Marine Life Sciences, Ocean University of China, Qingdao, China. .,Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China.
| | - Changming Bai
- Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China. .,Function Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Oceanography Laboratory, Qingdao, China.
| | - Chongming Wang
- Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China. .,Function Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Oceanography Laboratory, Qingdao, China.
| | - Xiaoling Song
- Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China. .,Function Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Oceanography Laboratory, Qingdao, China.
| | - Jie Huang
- Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China. .,Function Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Oceanography Laboratory, Qingdao, China.
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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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Dégremont L, Lamy JB, Pépin JF, Travers MA, Renault T. New Insight for the Genetic Evaluation of Resistance to Ostreid Herpesvirus Infection, a Worldwide Disease, in Crassostrea gigas. PLoS One 2015; 10:e0127917. [PMID: 26039375 PMCID: PMC4454582 DOI: 10.1371/journal.pone.0127917] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 04/20/2015] [Indexed: 11/19/2022] Open
Abstract
The Pacific oyster, Crassostrea gigas, is the most important commercial oyster species cultivated in the world. Meanwhile, the ostreid herpesvirus 1 (OsHV-1) is one of the major pathogens affecting the Pacific oyster, and numerous mortality outbreaks related to this pathogen are now reported worldwide. To assess the genetic basis of resistance to OsHV-1 infection in spat C. gigas and to facilitate breeding programs for such a trait, if any exist, we compared the mortality of half- and full-sib families using three field methods and a controlled challenge by OsHV-1 in the laboratory. In the field, three methods were tested: (A) one family per bag; (B) one family per small soft mesh bag and all families inside one bag; (C) same as the previous methods but the oysters were individually labelled and then mixed. The mean mortality ranged from 80 to 82% and was related to OsHV-1 based on viral DNA detection. The narrow-sense heritability for mortality, and thus OsHV-1 resistance, ranged from 0.49 to 0.60. The high positive genetic correlations across the field methods suggested no genotype by environment interaction. Ideally, selective breeding could use method B, which is less time- and space-consuming. The narrow sense heritability for mortality under OsHV-1 challenge was 0.61, and genetic correlation between the field and the laboratory was ranged from 0.68 to 0.75, suggesting a weak genotype by environment interaction. Thus, most of families showing the highest survival performed well in field and laboratory conditions, and a similar trend was also observed for families with the lowest survival. In conclusion, this is the first study demonstrating a large additive genetic variation for resistance to OsHV-1 infection in C. gigas, regardless of the methods used, which should help in selective breeding to improve resistance to viral infection in C. gigas.
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Affiliation(s)
- Lionel Dégremont
- Institut Français de Recherche pour l’Exploitation de la Mer, Laboratoire de Génétique et de Pathologie des Mollusques Marins, Avenue Mus de Loup, La Tremblade, France
| | - Jean-Baptiste Lamy
- Institut Français de Recherche pour l’Exploitation de la Mer, Laboratoire de Génétique et de Pathologie des Mollusques Marins, Avenue Mus de Loup, La Tremblade, France
| | - Jean-François Pépin
- Institut Français de Recherche pour l’Exploitation de la Mer, Laboratoire Environnement Ressources des Pertuis Charentais, Avenue Mus de Loup, La Tremblade, France
| | - Marie-Agnès Travers
- Institut Français de Recherche pour l’Exploitation de la Mer, Laboratoire de Génétique et de Pathologie des Mollusques Marins, Avenue Mus de Loup, La Tremblade, France
| | - Tristan Renault
- Institut Français de Recherche pour l’Exploitation de la Mer, Laboratoire de Génétique et de Pathologie des Mollusques Marins, Avenue Mus de Loup, La Tremblade, France
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42
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Dégremont L, Garcia C, Allen SK. Genetic improvement for disease resistance in oysters: A review. J Invertebr Pathol 2015; 131:226-41. [PMID: 26037230 DOI: 10.1016/j.jip.2015.05.010] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 05/12/2015] [Accepted: 05/13/2015] [Indexed: 10/23/2022]
Abstract
Oyster species suffer from numerous disease outbreaks, often causing high mortality. Because the environment cannot be controlled, genetic improvement for disease resistance to pathogens is an attractive option to reduce their impact on oyster production. We review the literature on selective breeding programs for disease resistance in oyster species, and the impact of triploidy on such resistance. Significant response to selection to improve disease resistance was observed in all studies after two to four generations of selection for Haplosporidium nelsoni and Roseovarius crassostrea in Crassostrea virginica, OsHV-1 in Crassostrea gigas, and Martelia sydneyi in Saccostrea glomerata. Clearly, resistance in these cases was heritable, but most of the studies failed to provide estimates for heritability or genetic correlations with other traits, e.g., between resistance to one disease and another. Generally, it seems breeding for higher resistance to one disease does not confer higher resistance or susceptibility to another disease. For disease resistance in triploid oysters, several studies showed that triploidy confers neither advantage nor disadvantage in survival, e.g., OsHV-1 resistance in C. gigas. Other studies showed higher disease resistance of triploids over diploid as observed in C. virginica and S. glomerata. One indirect mechanism for triploids to avoid disease was to grow faster, thus limiting the span of time when oysters might be exposed to disease.
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Affiliation(s)
- Lionel Dégremont
- SG2M, LGPMM, Ifremer, Avenue Mus de Loup, 17390 La Tremblade, France.
| | - Céline Garcia
- SG2M, LGPMM, Ifremer, Avenue Mus de Loup, 17390 La Tremblade, France.
| | - Standish K Allen
- Aquaculture Genetics and Breeding Technology Center, Virginia Institute of Marine Science, College of William and Mary, 1208 Greate Road, Gloucester Point, VA 23062-1346, USA.
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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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44
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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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45
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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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46
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Keeling SE, Brosnahan CL, Williams R, Gias E, Hannah M, Bueno R, McDonald WL, Johnston C. New Zealand juvenile oyster mortality associated with ostreid herpesvirus 1-an opportunistic longitudinal study. DISEASES OF AQUATIC ORGANISMS 2014; 109:231-239. [PMID: 24991849 DOI: 10.3354/dao02735] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
During the 2010-11 summer outbreak of ostreid herpesvirus 1 (OsHV-1) in New Zealand, an opportunistic longitudinal field study was conducted. OsHV-1 PCR-negative oyster spat (Crassostrea gigas) were relocated to an OsHV-1 PCR-positive area of the North Island of New Zealand that was experiencing juvenile oyster mortalities. Over a period of 13 d, spat were monitored for mortality, sampled for histopathology, and tested for the presence of OsHV-1 using real time PCR and Vibrio culture. Histopathology showed some evidence of tissue pathology; however, no consistent progressive pathology was apparent. Field mortalities were evident from Day 6 on. After 5 and 7 d of exposure, 83 and 100% of spat, respectively, tested positive for the virus by real time PCR. Vibrio species recovered during the longitudinal study included V. splendidus and V. aestuarianus. This study offers insight into the rapidity of onset and virulence of the virus in naïve oyster spat in New Zealand waters.
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Affiliation(s)
- S E Keeling
- Animal Health Laboratory, Investigation and Diagnostic Centre-Wallaceville, Ministry for Primary Industries, 66 Ward St, PO Box 40742, Upper Hutt 5018, New Zealand
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47
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Ostreid herpesvirus 1 infection among Pacific oyster (Crassostrea gigas) Spat: relevance of water temperature to virus replication and circulation prior to the onset of mortality. Appl Environ Microbiol 2014; 80:5419-26. [PMID: 24973071 DOI: 10.1128/aem.00484-14] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A number of bivalve species worldwide, including the Pacific oyster, Crassostrea gigas, have been affected by mass mortality events associated with herpesviruses, resulting in significant losses. A particular herpesvirus was purified from naturally infected larval Pacific oysters, and its genome was completely sequenced. This virus has been classified as Ostreid herpesvirus 1 (OsHV-1) within the family Malacoherpesviridae. Since 2008, mass mortality outbreaks among C. gigas in Europe have been related to the detection of a variant of OsHV-1 called μVar. Additional data are necessary to better describe mortality events in relation to environmental-parameter fluctuations and OsHV-1 detection. For this purpose, a single batch of Pacific oyster spat was deployed in 4 different locations in the Marennes-Oleron area (France): an oyster pond ("claire"), a shellfish nursery, and two locations in the field. Mortality rates were recorded based on regular observation, and samples were collected to search for and quantify OsHV-1 DNA by real-time PCR. Although similar massive mortality rates were reported at the 4 sites, mortality was detected earlier in the pond and in the nursery than at both field sites. This difference may be related to earlier increases in water temperature. Mass mortality was observed among oysters a few days after increases in the number of PCR-positive oysters and viral-DNA amounts were recorded. An initial increment in the number of PCR-positive oysters was reported at both field sites during the survey in the absence of significant mortality. During this period, the water temperature was below 16°C.
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48
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Renault T, Tchaleu G, Faury N, Moreau P, Segarra A, Barbosa-Solomieu V, Lapègue S. Genotyping of a microsatellite locus to differentiate clinical Ostreid herpesvirus 1 specimens. Vet Res 2014; 45:3. [PMID: 24410800 PMCID: PMC3897894 DOI: 10.1186/1297-9716-45-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2013] [Accepted: 12/19/2013] [Indexed: 11/13/2022] Open
Abstract
Ostreid herpesvirus 1 (OsHV-1) is a DNA virus belonging to the Malacoherpesviridae family from the Herpesvirales order. OsHV-1 has been associated with mortality outbreaks in different bivalve species including the Pacific cupped oyster, Crassostrea gigas. Since 2008, massive mortality events have been reported among C. gigas in Europe in relation to the detection of a variant of OsHV-1, called μVar. Since 2009, this variant has been mainly detected in France. These results raise questions about the emergence and the virulence of this variant. The search for association between specific virus genetic markers and clinical symptoms is of great interest and the characterization of the genetic variability of OsHV-1 specimens is an area of growing interest. Determination of nucleotide sequences of PCR-amplified virus DNA fragments has already been used to characterize OsHV-1 specimens and virus variants have thus been described. However, the virus DNA sequencing approach is time-consuming in the high-scale format. Identification and genotyping of highly polymorphic microsatellite loci appear as a suitable approach. The main objective of the present study was the development of a genotyping method in order to characterise clinical OsHV-1 specimens by targeting a particular microsatellite locus located in the ORF4 area. Genotyping results were compared to sequences already available. An excellent correlation was found between the detected genotypes and the corresponding sequences showing that the genotyping approach allowed an accuraté discrimination between virus specimens.
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Affiliation(s)
- Tristan Renault
- Ifremer, Unite Santé, Génétique et Microbiologie des Mollusques, Laboratoire de Génétique et Pathologie des Mollusques Marins, 17390 La Tremblade, France.
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49
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Jenkins C, Hick P, Gabor M, Spiers Z, Fell SA, Gu X, Read A, Go J, Dove M, O'Connor W, Kirkland PD, Frances J. Identification and characterisation of an ostreid herpesvirus-1 microvariant (OsHV-1 µ-var) in Crassostrea gigas (Pacific oysters) in Australia. DISEASES OF AQUATIC ORGANISMS 2013; 105:109-126. [PMID: 23872855 DOI: 10.3354/dao02623] [Citation(s) in RCA: 114] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Between November 2010 and January 2011, triploid Crassostrea gigas (Pacific oysters) cultivated in the Georges River, New South Wales, experienced >95% mortality. Mortalities also occurred in wild diploid C. gigas in the Georges River and shortly thereafter in the adjacent Parramatta River estuary upstream from Sydney Harbour. Neighbouring Saccostrea glomerata (Sydney rock oysters) did not experience mortalities in either estuary. Surviving oysters were collected to investigate the cause of mortalities. Histologically all oysters displayed significant pathology, and molecular testing revealed a high prevalence of ostreid herpesvirus-1 (OsHV-1). Quantitative PCR indicated that many C. gigas were carrying a high viral load at the time of sampling, while the load in S. glomerata was significantly lower (p < 0.001). Subsequent in situ hybridisation experiments confirmed the presence of a herpesvirus in C. gigas but not S. glomerata tissues, suggesting that S. glomerata is not susceptible to infection with OsHV-1. Naïve sentinel triploid C. gigas placed in the Georges River estuary in January 2011 quickly became infected and experienced nearly 100% mortality within 2 wk of exposure, indicating the persistence of the virus in the environment. Phylogenetic analysis of sequences derived from the C2/C6 region of the virus revealed that the Australian strain of OsHV-1 belongs to the microvariant (µ-var) cluster, which has been associated with severe mortalities in C. gigas in other countries since 2008. Environmental data revealed that the Woolooware Bay outbreaks occurred during a time of considerable environmental disturbance, with increased water temperatures, heavy rainfall, a toxic phytoplankton bloom and the presence of a pathogenic Vibrio sp. all potentially contributing to oyster stress. This is the first confirmed report of OsHV-1 µ-var related C. gigas mortalities in Australia.
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Affiliation(s)
- Cheryl Jenkins
- NSW Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Menangle, Australia.
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