1
|
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.
Collapse
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
| |
Collapse
|
2
|
de Kantzow M, Hick PM, Whittington RJ. Immune Priming of Pacific Oysters ( Crassostrea gigas) to Induce Resistance to Ostreid herpesvirus 1: Comparison of Infectious and Inactivated OsHV-1 with Poly I:C. Viruses 2023; 15:1943. [PMID: 37766349 PMCID: PMC10536431 DOI: 10.3390/v15091943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 09/08/2023] [Accepted: 09/13/2023] [Indexed: 09/29/2023] Open
Abstract
Pacific oyster mortality syndrome (POMS), which is caused by Ostreid herpesvirus 1 (OsHV-1), causes economic losses in Pacific oyster (Crassostrea gigas) aquaculture in many countries. Reducing the mortality in disease outbreaks requires changing the host, pathogen and environment interactions to favor the host. Survivors of natural exposure to OsHV-1 are able to survive subsequent outbreaks. This has been replicated under laboratory conditions, suggesting the existence of an immune response. The aim of the present study is to compare the effects of prior exposure to infectious OsHV-1, heat-inactivated OsHV-1 and the chemical anti-viral immune stimulant poly I:C on mortality following exposure to virulent OsHV-1. All treatments were administered by intramuscular injection. Oysters were maintained at 18 °C for 14 days; then, the temperature was increased to 22 °C and the oysters were challenged with virulent OsHV-1. Heat-inactivated OsHV-1, infectious OsHV-1 and poly I:C all induced significant protection against mortality, with the hazard of death being 0.41, 0.18 and 0.02, respectively, compared to the controls, which had no immune priming. The replication of OsHV-1 on first exposure was not required to induce a protective response. While the underlying mechanisms for protection remain to be elucidated, conditioning for resistance to POMS by prior exposure to inactivated or infectious OsHV-1 may have practical applications in oyster farming but requires further development to optimize the dose and delivery mechanism and evaluate the duration of protection.
Collapse
Affiliation(s)
| | | | - Richard J. Whittington
- School of Veterinary Science, Faculty of Science, The University of Sydney, 425 Werombi Road, Camden, NSW 2570, Australia
| |
Collapse
|
3
|
Liu OM, Hick PM, Whittington RJ. The Resistance to Lethal Challenge with Ostreid herpesvirus-1 of Pacific Oysters ( Crassostrea gigas) Previously Exposed to This Virus. Viruses 2023; 15:1706. [PMID: 37632048 PMCID: PMC10458589 DOI: 10.3390/v15081706] [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: 07/25/2023] [Revised: 08/06/2023] [Accepted: 08/07/2023] [Indexed: 08/27/2023] Open
Abstract
Pacific oyster (Crassostrea gigas) aquaculture has been economically impacted in many countries by Pacific oyster mortality syndrome (POMS), a disease initiated by Ostreid herpesvirus 1. The objectives of this study were to determine whether naturally exposed, adult C. gigas could act as reservoirs for OsHV-1 and explain the recurrent seasonal outbreaks of POMS and to test whether or not they were resistant to OsHV-1. In a laboratory infection experiment using thermal shock, OsHV-1 replication was not reactivated within the tissues of such oysters and the virus was not transmitted to naïve cohabitating spat. The adult oysters were resistant to intramuscular injection with a lethal dose of OsHV-1 and had 118 times lower risk of mortality than naïve oysters. Considered together with the results of other studies in C. gigas, natural exposure or laboratory exposure to OsHV-1 may result in immunity during subsequent exposure events, either in the natural environment or the laboratory. While adult C. gigas can carry OsHV-1 infection for lengthy periods, reactivation of viral replication leading to mortality and transmission of the virus to naïve oysters may require specific conditions that were not present in the current experiment. Further investigation is required to evaluate the mechanisms responsible for resistance to disease in oysters previously exposed to OsHV-1, whether immunity can be exploited commercially to prevent POMS outbreaks and to determine the source of the virus for recurrent seasonal outbreaks.
Collapse
Affiliation(s)
- Olivia M. Liu
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, 425 Werombi Road, Camden, NSW 2570, Australia; (O.M.L.); (P.M.H.)
- Biosecurity Animal Division, Australian Government Department of Agriculture, Fisheries and Forestry, Canberra, ACT 2601, Australia
| | - Paul M. Hick
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, 425 Werombi Road, Camden, NSW 2570, Australia; (O.M.L.); (P.M.H.)
- Elizabeth Macarthur Agricultural Institute, Woodbridge Road, Menangle, NSW 2568, Australia
| | - Richard J. Whittington
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, 425 Werombi Road, Camden, NSW 2570, Australia; (O.M.L.); (P.M.H.)
| |
Collapse
|
4
|
Combe M, Reverter M, Caruso D, Pepey E, Gozlan RE. Impact of Global Warming on the Severity of Viral Diseases: A Potentially Alarming Threat to Sustainable Aquaculture Worldwide. Microorganisms 2023; 11:microorganisms11041049. [PMID: 37110472 PMCID: PMC10146364 DOI: 10.3390/microorganisms11041049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 04/12/2023] [Accepted: 04/13/2023] [Indexed: 04/29/2023] Open
Abstract
With an ever-increasing human population, food security remains a central issue for the coming years. The magnitude of the environmental impacts of food production has motivated the assessment of the environmental and health benefits of shifting diets, from meat to fish and seafood. One of the main concerns for the sustainable development of aquaculture is the emergence and spread of infectious animal diseases in a warming climate. We conducted a meta-analysis to investigate the influence of global warming on mortality due to viral infections in farmed aquatic animals. We found a positive trend between increasing temperature and increasing viral virulence, with an increase in water temperature of 1 °C resulting in an increase in mortality of 1.47-8.33% in OsHV-1 infected oysters, 2.55-6.98% in carps infected with CyHV-3 and 2.18-5.37% in fishes infected with NVVs. We suggest that global warming is going to pose a risk of viral disease outbreaks in aquaculture and could compromise global food security.
Collapse
Affiliation(s)
- Marine Combe
- ISEM, Université de Montpellier, CNRS, IRD, 34095 Montpellier, France
| | - Miriam Reverter
- ISEM, Université de Montpellier, CNRS, IRD, 34095 Montpellier, France
- Marine Biology and Ecology Research Centre, School of Biological and Marine Sciences, University of Plymouth, Plymouth PL4 8AA, UK
| | - Domenico Caruso
- ISEM, Université de Montpellier, CNRS, IRD, 34095 Montpellier, France
| | - Elodie Pepey
- ISEM, Université de Montpellier, CNRS, IRD, 34095 Montpellier, France
- CIRAD, UMR ISEM, 34398 Montpellier, France
| | | |
Collapse
|
5
|
Trancart S, Tweedie A, Liu O, Paul-Pont I, Hick P, Houssin M, Whittington RJ. Diversity and molecular epidemiology of Ostreid herpesvirus 1 in farmed Crassostrea gigas in Australia: Geographic clusters and implications for "microvariants" in global mortality events. Virus Res 2023; 323:198994. [PMID: 36332723 PMCID: PMC10194400 DOI: 10.1016/j.virusres.2022.198994] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Revised: 10/26/2022] [Accepted: 10/31/2022] [Indexed: 11/08/2022]
Abstract
Since 2010, mass mortality events known as Pacific oyster mortality syndrome (POMS) have occurred in Crassostrea gigas in Australia associated with Ostreid herpesvirus 1. The virus was thought to be an OsHV-1 µVar or "microvariant", i.e. one of the dominant variants associated with POMS in Europe, but there are few data to characterize the genotype in Australia. Consequently, the genetic identity and diversity of the virus was determined to understand the epidemiology of the disease in Australia. Samples were analysed from diseased C. gigas over five summer seasons between 2011 and 2016 in POMS-affected estuaries: Georges River in New South Wales (NSW), Hawkesbury River (NSW) and Pitt Water in Tasmania. Sequencing was attempted for six genomic regions. Numerous variants were identified among these regions (n = 100 isolates) while twelve variants were identified from concatenated nucleotide sequences (n = 61 isolates). Nucleotide diversity of the seven genotypes of C region among Australian isolates (Pi 0.99 × 10-3) was the lowest globally. All Australian isolates grouped in a cluster distinct from other OsHV-1 isolates worldwide. This is the first report that Australian outbreaks of POMS were associated with OsHV-1 distinct from OsHV-1 reference genotype, µVar and other microvariants from other countries. The findings illustrate that microvariants are not the only variants of OsHV-1 associated with mass mortality events in C. gigas. In addition, there was mutually exclusive spatial clustering of viral genomic and amino acid sequence variants between estuaries, and a possible association between genotype/amino acid sequence and the prevalence and severity of POMS, as this differed between these estuaries. The sequencing findings supported prior epidemiological evidence for environmental reservoirs of OsHV-1 for POMS outbreaks in Australia.
Collapse
Affiliation(s)
- Suzanne Trancart
- LABÉO Research Department, 1 Route de Rosel, Cedex 4, Caen 14053, France
| | - Alison Tweedie
- The University of Sydney, Sydney School of Veterinary Science, Faculty of Science, 425 Werombi Rd, Camden, NSW 2570, Australia; Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Menangle, NSW 2568, Australia
| | - Olivia Liu
- The University of Sydney, Sydney School of Veterinary Science, Faculty of Science, 425 Werombi Rd, Camden, NSW 2570, Australia; Department of Agriculture, Water and the Environment, Canberra, ACT 2601, Australia
| | - Ika Paul-Pont
- The University of Sydney, Sydney School of Veterinary Science, Faculty of Science, 425 Werombi Rd, Camden, NSW 2570, Australia; LEMAR, Rue Dumont d'Urville, Plouzané 29280, France
| | - Paul Hick
- The University of Sydney, Sydney School of Veterinary Science, Faculty of Science, 425 Werombi Rd, Camden, NSW 2570, Australia; Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Menangle, NSW 2568, Australia
| | - Maryline Houssin
- LABÉO Research Department, 1 Route de Rosel, Cedex 4, Caen 14053, France; UMR BOREA Université de Caen Normandie, MNHN, CNRS 8067, SU, IRD 207, UCN, UA, Esplanade de la Paix Caen Cedex 4 14032, France
| | - Richard J Whittington
- The University of Sydney, Sydney School of Veterinary Science, Faculty of Science, 425 Werombi Rd, Camden, NSW 2570, Australia.
| |
Collapse
|
6
|
Fuhrmann M, Georgiades E, Cattell G, Brosnahan C, Lane HS, Hick PM. Aquatic pathogens and biofouling: pilot study of ostreid herpesvirus 1 translocation by bivalves. BIOFOULING 2021; 37:949-963. [PMID: 34628999 DOI: 10.1080/08927014.2021.1985474] [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: 04/22/2021] [Revised: 09/16/2021] [Accepted: 09/21/2021] [Indexed: 06/13/2023]
Abstract
Ostreid herpesvirus 1 (OsHV-1) has caused mass mortalities in Pacific oysters (Crassostrea gigas) in Europe, Australia, and New Zealand. While aquaculture-associated movements of infected Pacific oysters are a well-known cause of OsHV-1 spread once established in a region, translocation via biofouling of aquaculture equipment or vessels needs further investigation to explain the more distant spread of OsHV-1. Laboratory experiments were designed to test for transmission of OsHV-1 between infected and naïve Pacific oysters via a simulated biofouling translocation scenario. Three common biofouling species [Sydney rock oysters (Saccostrea glomerata), Mediterranean mussels (Mytilus galloprovincialis) and Pacific oysters] were tested as intermediaries using a cohabitation challenge with Pacific oysters infected by injection. Transmission occurred, albeit for one of eight replicates when Pacific oysters were the intermediary species. This demonstrated a possible pathway for pathogen spread via biofouling containing Pacific oysters while highlighting the complexity of OsHV-1 transmission. Such complexities require further investigation to inform future risk assessments and management of fouled aquaculture equipment and vessels.
Collapse
Affiliation(s)
- M Fuhrmann
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, Camden, New South Wales, Australia
| | - E Georgiades
- Ministry for Primary Industries, Wellington, New Zealand
| | - G Cattell
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, Camden, New South Wales, Australia
| | - C Brosnahan
- Ministry for Primary Industries, Wellington, New Zealand
| | - H S Lane
- Ministry for Primary Industries, Wellington, New Zealand
| | - P M Hick
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, Camden, New South Wales, Australia
| |
Collapse
|
7
|
Reduction in Virulence over Time in Ostreid herpesvirus 1 (OsHV-1) Microvariants between 2011 and 2015 in Australia. Viruses 2021; 13:v13050946. [PMID: 34065570 PMCID: PMC8160646 DOI: 10.3390/v13050946] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/06/2021] [Accepted: 05/17/2021] [Indexed: 01/05/2023] Open
Abstract
Microvariant genotypes of Ostreid herpesvirus 1 (OsHV-1) are associated with mass mortality events of Pacific oysters in many countries. The OsHV-1 microvariant (µVar) emerged in France 2008 and caused significant economic losses as it became endemic and displaced the previously dominant OsHV-1 reference genotype. Recently, considerable genotypic variation has been described for OsHV-1 microvariants, however, less is known about variation in viral phenotype. This study used an in vivo laboratory infection model to assess differences in total cumulative mortality, peak viral load, transmissibility, and dose-response for three OsHV-1 isolates obtained between 2011 and 2015 from endemic waterways in Australia. This followed field observations of apparent reductions in the severity of mass mortalities over this time. Significantly higher hazard of death and cumulative mortality were observed for an isolate obtained in 2011 compared to isolates from 2014–2015. In keeping with other studies, the hazard of death was higher in oysters challenged by injection compared to challenge by cohabitation and the mortality was higher when the initial dose was 1 × 104 OsHV-1 DNA copies per oyster injection compared to 1 × 102 DNA copies. There was no difference in the quantity of OsHV-1 DNA at time of death that could be related to isolate or dose, suggesting similar pathogenetic processes in the individual oysters that succumbed to end-stage disease. While the isolates examined in this study were biased towards pathogenic types of OsHV-1, as they were collected during disease outbreaks, the variation in virulence that was observed, when combined with prior data on subclinical infections, suggests that surveillance for low virulence genotypes of OsHV-1 would be rewarding. This may lead to new approaches to disease management which utilize controlled exposure to attenuated strains of OsHV-1.
Collapse
|
8
|
Pernet F, Lugué K, Petton B. Competition for food reduces disease susceptibility in a marine invertebrate. Ecosphere 2021. [DOI: 10.1002/ecs2.3435] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Affiliation(s)
- Fabrice Pernet
- Ifremer CNRS IRD LEMAR University of Brest PlouzaneF‐29280France
| | - Klervi Lugué
- Ifremer CNRS IRD LEMAR University of Brest PlouzaneF‐29280France
| | - Bruno Petton
- Ifremer CNRS IRD LEMAR University of Brest PlouzaneF‐29280France
| |
Collapse
|
9
|
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.
Collapse
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.
| |
Collapse
|
10
|
Agnew MV, Friedman CS, Langdon C, Divilov K, Schoolfield B, Morga B, Degremont L, Dhar AK, Kirkland P, Dumbauld B, Burge CA. Differential Mortality and High Viral Load in Naive Pacific Oyster Families Exposed to OsHV-1 Suggests Tolerance Rather than Resistance to Infection. Pathogens 2020; 9:E1057. [PMID: 33348814 PMCID: PMC7766980 DOI: 10.3390/pathogens9121057] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 12/15/2020] [Accepted: 12/15/2020] [Indexed: 11/25/2022] Open
Abstract
Pacific oysters, Crassostrea gigas, are one of the most productive aquaculture species in the world. However, they are threatened by the spread of Ostreid herpesvirus-1 (OsHV-1) and its microvariants (collectively "µvars"), which cause mass mortalities in all life stages of Pacific oysters globally. Breeding programs have been successful in reducing mortality due to OsHV-1 variants following viral outbreaks; however, an OsHV-1-resistant oyster line does not yet exist in the United States (US), and it is unknown how OsHV-1 µvars will affect US oyster populations compared to the current variant, which is similar to the OsHV-1 reference, found in Tomales Bay, CA. The goals of this study were to investigate the resistance of C. gigas juveniles produced by the Molluscan Broodstock Program (MBP) to three variants of OsHV-1: a California reference OsHV-1, an Australian µvar, and a French µvar. This is the first study to directly compare OsHV-1 µvars to a non-µvar. The survival probability of oysters exposed to the French (FRA) or Australian (AUS) µvar was significantly lower (43% and 71%, respectively) than to the reference variant and controls (96%). No oyster family demonstrated resistance to all three OsHV-1 variants, and many surviving oysters contained high copy numbers of viral DNA (mean ~3.53 × 108). These results indicate that the introduction of OsHV-1 µvars could have substantial effects on US Pacific oyster aquaculture if truly resistant lines are not achieved, and highlight the need to consider resistance to infection in addition to survival as traits in breeding programs to reduce the risk of the spread of OsHV-1 variants.
Collapse
Affiliation(s)
- M. Victoria Agnew
- Institute of Marine and Environmental Technology, University of Maryland Baltimore County, Baltimore, MD 21202, USA;
| | - Carolyn S. Friedman
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA 98195, USA;
| | - Christopher Langdon
- Department of Fisheries and Wildlife, Coastal Oregon Marine Experiment Station, Hatfield Marine Science Center, Newport, OR 97365, USA; (C.L.); (K.D.); (B.S.)
| | - Konstantin Divilov
- Department of Fisheries and Wildlife, Coastal Oregon Marine Experiment Station, Hatfield Marine Science Center, Newport, OR 97365, USA; (C.L.); (K.D.); (B.S.)
| | - Blaine Schoolfield
- Department of Fisheries and Wildlife, Coastal Oregon Marine Experiment Station, Hatfield Marine Science Center, Newport, OR 97365, USA; (C.L.); (K.D.); (B.S.)
| | - Benjamin Morga
- Ifremer, SG2M, LGPMM, 17390 La Tremblade, France; (B.M.); (L.D.)
| | - Lionel Degremont
- Ifremer, SG2M, LGPMM, 17390 La Tremblade, France; (B.M.); (L.D.)
| | - Arun K. Dhar
- Aquaculture Pathology Laboratory, School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ 85721, USA;
| | - Peter Kirkland
- NSW Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Menangle, NSW 2568, Australia;
| | - Brett Dumbauld
- Hatfield Marine Science Center, USDA-ARS, Newport, OR 97365, USA;
| | - Colleen A. Burge
- Institute of Marine and Environmental Technology, University of Maryland Baltimore County, Baltimore, MD 21202, USA;
| |
Collapse
|
11
|
Friedman CS, Reece KS, Wippel BJT, Agnew MV, Dégremont L, Dhar AK, Kirkland P, MacIntyre A, Morga B, Robison C, Burge CA. Unraveling concordant and varying responses of oyster species to Ostreid Herpesvirus 1 variants. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 739:139752. [PMID: 32846506 DOI: 10.1016/j.scitotenv.2020.139752] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 05/12/2020] [Accepted: 05/25/2020] [Indexed: 06/11/2023]
Abstract
The Ostreid herpesvirus 1 (OsHV-1) and variants, particularly the microvariants (μVars), are virulent and economically devastating viruses impacting oysters. Since 2008 OsHV-1 μVars have emerged rapidly having particularly damaging effects on aquaculture industries in Europe, Australia and New Zealand. We conducted field trials in Tomales Bay (TB), California where a non-μVar strain of OsHV-1 is established and demonstrated differential mortality of naturally exposed seed of three stocks of Pacific oyster, Crassostrea gigas, and one stock of Kumamoto oyster, C. sikamea. Oysters exposed in the field experienced differential mortality that ranged from 64 to 99% in Pacific oysters (Tasmania>Midori = Willapa stocks), which was much higher than that of Kumamoto oysters (25%). Injection trials were done using French (FRA) and Australian (AUS) μVars with the same oyster stocks as planted in the field and, in addition, two stocks of the Eastern oyster, C. virginica. No mortality was observed in control oysters. One C. virginica stock suffered ~10% mortality when challenged with both μVars tested. Two Pacific oyster stocks suffered 75 to 90% mortality, while one C. gigas stock had relatively low mortality when challenged with the AUS μVar (~22%) and higher mortality when challenged with the French μVar (~72%). Conversely, C. sikamea suffered lower mortality when challenged with the French μVar (~22%) and higher mortality with the AUS μVar (~44%). All dead oysters had higher viral loads (~1000×) as measured by quantitative PCR relative to those that survived. However, some survivors had high levels of virus, including those from species with lower mortality. Field mortality in TB correlated with laboratory mortality of the FRA μVar (69% correlation) but not with that of the AUS μVar, which also lacked correlation with the FRA μVar. The variation in response to OsHV-1 variant challenges by oyster species and stocks demonstrates the need for empirical assessment of multiple OsHV-1 variants.
Collapse
Affiliation(s)
- Carolyn S Friedman
- School of Aquatic & Fishery Sciences, University of Washington, Box 355020, Seattle, WA 98105, USA
| | - Kimberly S Reece
- Virginia Institute of Marine Sciences, William & Mary, P.O. Box 1346, Gloucester Point, Virginia 23062, USA
| | - Bryanda J T Wippel
- School of Aquatic & Fishery Sciences, University of Washington, Box 355020, Seattle, WA 98105, USA
| | - M Victoria Agnew
- Institute of Marine and Environmental Technology, University of Maryland Baltimore County, 701 E Pratt Street, Baltimore, MD 21202, USA
| | - Lionel Dégremont
- Ifremer, SG2M-LGPMM, Station La Tremblade, 17390 La Tremblade, France
| | - Arun K Dhar
- Aquaculture Pathology Laboratory, Animal and Comparative Biomedical Sciences, The University of Arizona, 1117 E Lowell Road, Tucson, AZ 85721, USA
| | - Peter Kirkland
- Elizabeth Macarthur Agricultural Institute, NSW Department of Primary Industries, Menangle, NSW 2568, Australia
| | - Alanna MacIntyre
- Virginia Institute of Marine Sciences, William & Mary, P.O. Box 1346, Gloucester Point, Virginia 23062, USA
| | - Benjamin Morga
- Ifremer, SG2M-LGPMM, Station La Tremblade, 17390 La Tremblade, France
| | - Clara Robison
- Virginia Institute of Marine Sciences, William & Mary, P.O. Box 1346, Gloucester Point, Virginia 23062, USA
| | - Colleen A Burge
- Institute of Marine and Environmental Technology, University of Maryland Baltimore County, 701 E Pratt Street, Baltimore, MD 21202, USA.
| |
Collapse
|
12
|
Fleury E, Barbier P, Petton B, Normand J, Thomas Y, Pouvreau S, Daigle G, Pernet F. Latitudinal drivers of oyster mortality: deciphering host, pathogen and environmental risk factors. Sci Rep 2020; 10:7264. [PMID: 32350335 PMCID: PMC7190702 DOI: 10.1038/s41598-020-64086-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 04/04/2020] [Indexed: 11/25/2022] Open
Abstract
Diseases pose an ongoing threat to aquaculture, fisheries and conservation of marine species, and determination of risk factors of disease is crucial for management. Our objective was to decipher the effects of host, pathogen and environmental factors on disease-induced mortality of Pacific oysters (Crassostrea gigas) across a latitudinal gradient. We deployed young and adult oysters at 13 sites in France and we monitored survival, pathogens and environmental parameters. The young oysters came from either the wild collection or the hatchery while the adults were from the wild only. We then used Cox regression models to investigate the effect of latitude, site, environmental factors and origin on mortality risk and to extrapolate this mortality risk to the distribution limits of the species in Europe. We found that seawater temperature, food level, sea level atmospheric pressure, rainfall and wind speed were associated with mortality risk. Their effect on hatchery oysters was generally higher than on wild animals, probably reflecting that hatchery oysters were free of Ostreid herpesvirus 1 (OsHV-1) whereas those from the wild were asymptomatic carriers. The risk factors involved in young and adult oyster mortalities were different, reflecting distinct diseases. Mortality risk increases from 0 to 90% with decreasing latitude for young hatchery oysters, but not for young wild oysters or adults. Mortality risk was higher in wild oysters than in hatchery ones at latitude > 47.6°N while this was the opposite at lower latitude. Therefore, latitudinal gradient alters disease-induced mortality risk but interacts with the initial health status of the host and the pathogen involved. Practically, we suggest that mortality can be mitigated by using hatchery oysters in north and wild collected oysters in the south.
Collapse
Affiliation(s)
- Elodie Fleury
- Univ Brest, Ifremer, CNRS, IRD, LEMAR, F-29280, Plouzane, France.
| | - Pierrick Barbier
- Univ Brest, Ifremer, CNRS, IRD, LEMAR, F-29280, Plouzane, France
| | - Bruno Petton
- Univ Brest, Ifremer, CNRS, IRD, LEMAR, F-29280, Plouzane, France
| | - Julien Normand
- Ifremer, Laboratoire Environnement Ressources de Normandie, 14520, Port en Bessin, France
| | - Yoann Thomas
- Univ Brest, Ifremer, CNRS, IRD, LEMAR, F-29280, Plouzane, France
| | | | - Gaétan Daigle
- Département de Mathématiques et Statistique, Université Laval, Sainte-Foy, Québec, G1K 7P4, Canada
| | - Fabrice Pernet
- Univ Brest, Ifremer, CNRS, IRD, LEMAR, F-29280, Plouzane, France
| |
Collapse
|
13
|
Liu O, Paul-Pont I, Rubio A, Dhand N, Whittington RJ. Detection of ostreid herpesvirus-1 in plankton and seawater samples at an estuary scale. DISEASES OF AQUATIC ORGANISMS 2020; 138:1-15. [PMID: 32132267 DOI: 10.3354/dao03445] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Ostreid herpesvirus-1 (OsHV-1) is known to associate with particles in seawater, leading to infection and disease in the Pacific oyster Crassostrea gigas. The estuarine environment is highly complex and changeable, and this needs to be considered when collecting environmental samples for pathogen detection. The aims of this study were to (1) compare different aspects of collecting natural seawater and plankton samples for detection of OsHV-1 DNA and (2) determine whether detection of OsHV-1 DNA in such environmental samples has merit for disease risk prediction. The results of one experiment suggest that sampling on the outgoing tide may improve the detection of OsHV-1 DNA in seawater and plankton tow samples (odds ratio 2.71). This statistical comparison was not possible in 2 other experiments. The method (plankton tow or beta bottle) and depth of collection (range: 250-1250 mm) had no effect on the likelihood of detection of OsHV-1. OsHV-1 DNA was found at low concentrations in plankton tow and seawater samples, and only when outbreaks of mortality associated with OsHV-1 were observed in nearby experimental or farmed populations of C. gigas. This suggests that single point in time environmental samples of seawater or plankton are not sufficient to rule out the presence of OsHV-1 in an estuary. The association of OsHV-1 with particles in seawater needs to be better understood in order to determine whether more selective and sensitive methods can be devised to detect it, before environmental samples can be reliably used in disease risk prediction.
Collapse
Affiliation(s)
- Olivia Liu
- School of Veterinary Science, Faculty of Science, The University of Sydney, Camden, NSW 2570, Australia
| | | | | | | | | |
Collapse
|
14
|
Different in vivo growth of ostreid herpesvirus 1 at 18 °C and 22 °C alters mortality of Pacific oysters (Crassostrea gigas). Arch Virol 2019; 164:3035-3043. [PMID: 31602543 DOI: 10.1007/s00705-019-04427-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 09/09/2019] [Indexed: 01/29/2023]
Abstract
Seasonally recurrent outbreaks of mass mortality in Pacific oysters (Crassostrea gigas) caused by microvariant genotypes of ostreid herpesvirus 1 (OsHV-1) occur in Europe, New Zealand and Australia. The incubation period for OsHV-1 under experimental conditions is 48-72 hours and depends on water temperature, as does the mortality. An in vivo growth curve for OsHV-1 was determined by quantifying OsHV-1 DNA at 10 time points between 2 and 72 hours after exposure to OsHV-1. The peak replication rate was the same at 18 °C and 22 °C; however, there was a longer period of amplification leading to a higher peak concentration at 22 °C (2.34 × 107 copies/mg at 18 hours) compared to 18 °C (1.38 × 105 copies/mg at 12 hours). The peak viral concentration preceded mortality by 72 hours and 20 hours at 18 °C and 22 °C, respectively. Cumulative mortality to day 14 was 45.9% at 22 °C compared to 0.3% at 18 °C. The prevalence of OsHV-1 infection after 14 days at 18 °C was 33.3%. No mortality from OsHV-1 occurred when the water temperature in tanks of oysters challenged at 18 °C was increased to 22 °C for 14 days. The influence of water temperature prior to exposure to OsHV-1 and during the initial virus replication is an important determinant of the outcome of infection in C. gigas.
Collapse
|
15
|
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.
Collapse
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
| | | | | | | | | | | |
Collapse
|
16
|
Pathirana E, Fuhrmann M, Whittington R, Hick P. Influence of environment on the pathogenesis of Ostreid herpesvirus-1 (OsHV-1) infections in Pacific oysters ( Crassostrea gigas) through differential microbiome responses. Heliyon 2019; 5:e02101. [PMID: 31372553 PMCID: PMC6656993 DOI: 10.1016/j.heliyon.2019.e02101] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 04/26/2019] [Accepted: 07/15/2019] [Indexed: 01/07/2023] Open
Abstract
The oyster microbiome is thought to contribute to the pathogenesis of mass mortality disease in Pacific oysters, associated with OsHV-1. As filter-feeders, oysters host a microbiota that can be influenced by the estuarine environment. This may alter susceptibility to OsHV-1 infections, causing variable mortality. This study aimed at: (1) differences in the microbiome of Pacific oysters with a common origin but grown in geographically distinct estuaries; (2) evaluating changes occurring in the microbiota, especially in Vibrio, and (3) differential responses of the oyster microbiome, in response to an OsHV-1 infection. Pacific oysters sourced from a single hatchery but raised separately in Patonga Creek, Shoalhaven River and Clyde River of NSW, Australia, were used and challenged with OsHV-1. The initial microbiome composition was different in the three batches and changed further, post-injection (p < 0.05). The Patonga oysters with the highest mortality also had higher OsHV-1 and Vibrio quantities compared to the other two batches (p < 0.05). The higher initial bacterial diversity in Patonga oysters decreased in moribund oysters which was not observed in the other two batches (p < 0.05). The microbiome of survivors of OsHV-1 infection and negative control oysters of two batches, did not show any changes with the relevant pre-challenged microbiome. A strong correlation was observed between the OsHV-1 and Vibrio quantities in OsHV-1 infected oysters (r = 0.6; p < 0.001). In conclusion, the Pacific oyster microbiome differed in different batches despite a common hatchery origin. Different microbiomes responded differently with a differential outcome of OsHV-1 challenge. The higher Vibrio load in oysters with higher OsHV-1 content and higher mortality, suggests a role in Vibrio in the pathogenesis of this mortality disease. This study provided insights of the potential of different estuarine environments to shape the Pacific oyster microbiome and how different microbiomes are associated with different outcomes of OsHV-1 infection.
Collapse
|
17
|
Toldrà A, Andree KB, Bertomeu E, Roque A, Carrasco N, Gairín I, Furones MD, Campàs M. Rapid capture and detection of ostreid herpesvirus-1 from Pacific oyster Crassostrea gigas and seawater using magnetic beads. PLoS One 2018; 13:e0205207. [PMID: 30281676 PMCID: PMC6169968 DOI: 10.1371/journal.pone.0205207] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 09/20/2018] [Indexed: 12/20/2022] Open
Abstract
Ostreid herpesvirus-1 (OsHV-1) has been involved in mass mortality episodes of Pacific oysters Crassostrea gigas throughout the world, causing important economic losses to the aquaculture industry. In the present study, magnetic beads (MBs) coated with an anionic polymer were used to capture viable OsHV-1 from two types of naturally infected matrix: oyster homogenate and seawater. Adsorption of the virus on the MBs and characterisation of the MB-virus conjugates was demonstrated by real-time quantitative PCR (qPCR). To study the infective capacity of the captured virus, MB-virus conjugates were injected in the adductor muscle of naïve spat oysters, using oyster homogenate and seawater without MBs as positive controls, and bare MBs and sterile water as negative controls. Mortalities were induced after injection with MB-virus conjugates and in positive controls, whereas no mortalities were recorded in negative controls. Subsequent OsHV-1 DNA and RNA analysis of the oysters by qPCR and reverse transcription qPCR (RT-qPCR), respectively, confirmed that the virus was the responsible for the mortality event and the ability of the MBs to capture viable viral particles. The capture of viable OsHV-1 using MBs is a rapid and easy isolation method and a promising tool, combined with qPCR, to be applied to OsHV-1 detection in aquaculture facilities.
Collapse
Affiliation(s)
- Anna Toldrà
- IRTA, Ctra., Sant Carles de la Ràpita, Tarragona, Spain
| | | | | | - Ana Roque
- IRTA, Ctra., Sant Carles de la Ràpita, Tarragona, Spain
| | | | - Ignasi Gairín
- IRTA, Ctra., Sant Carles de la Ràpita, Tarragona, Spain
| | | | - Mònica Campàs
- IRTA, Ctra., Sant Carles de la Ràpita, Tarragona, Spain
- * E-mail:
| |
Collapse
|
18
|
Pernet F, Fuhrmann M, Petton B, Mazurié J, Bouget JF, Fleury E, Daigle G, Gernez P. Determination of risk factors for herpesvirus outbreak in oysters using a broad-scale spatial epidemiology framework. Sci Rep 2018; 8:10869. [PMID: 30022088 PMCID: PMC6052024 DOI: 10.1038/s41598-018-29238-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 07/06/2018] [Indexed: 11/09/2022] Open
Abstract
Marine diseases have major impacts on ecosystems and economic consequences for aquaculture and fisheries. Understanding origin, spread and risk factors of disease is crucial for management, but data in the ocean are limited compared to the terrestrial environment. Here we investigated how the marine environment drives the spread of viral disease outbreak affecting The Pacific oyster worldwide by using a spatial epidemiology framework. We collected environmental and oyster health data at 46 sites spread over an area of 300 km2 along an inshore-offshore gradient during an epizootic event and conducted risk analysis. We found that disease broke out in the intertidal farming area and spread seaward. Mortalities and virus detection were observed in oysters placed 2 km from the farming areas, but oysters of almost all sites were subclinically infected. Increasing food quantity and quality, growth rate and energy reserves of oyster were associated with a lower risk of mortality offshore whereas increasing turbidity, a proxy of the concentration of suspended particulate matter, and terrestrial inputs, inferred from fatty acid composition of oysters, were associated with a higher risk of mortality. Offshore farming and maintenance of good ecological status of coastal waters are options to limit disease risk in oysters.
Collapse
Affiliation(s)
- Fabrice Pernet
- Ifremer, Unité de Physiologie Fonctionnelle des Organisme Marins, LEMAR UMR 6539, Technopole de Brest-Iroise, Plouzané, France.
| | - Marine Fuhrmann
- Ifremer, Unité de Physiologie Fonctionnelle des Organisme Marins, LEMAR UMR 6539, Technopole de Brest-Iroise, Plouzané, France
| | - Bruno Petton
- Ifremer, Unité de Physiologie Fonctionnelle des Organisme Marins, LEMAR UMR 6539, Presqu'île du vivier, Argenton, France
| | - Joseph Mazurié
- Ifremer, Unité Littorale, Laboratoire Environnement Ressource du Morbihan Pays-de-la-Loire, 12 Rue des Résistants, La Trinité-sur-Mer, France
| | - Jean-François Bouget
- Ifremer, Unité Littorale, Laboratoire Environnement Ressource du Morbihan Pays-de-la-Loire, 12 Rue des Résistants, La Trinité-sur-Mer, France
| | - Elodie Fleury
- Ifremer, Unité de Physiologie Fonctionnelle des Organisme Marins, LEMAR UMR 6539, Technopole de Brest-Iroise, Plouzané, France
| | - Gaétan Daigle
- Université Laval, Département de mathématiques et de statistique, Pavillon Alexandre-Vachon, Québec, QC, Canada
| | - Pierre Gernez
- Mer Molécules Santé (EA 2160), Université de Nantes, Nantes, France
| |
Collapse
|
19
|
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.
Collapse
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
| |
Collapse
|
20
|
Whittington RJ, Paul-Pont I, Evans O, Hick P, Dhand NK. Counting the dead to determine the source and transmission of the marine herpesvirus OsHV-1 in Crassostrea gigas. Vet Res 2018; 49:34. [PMID: 29636093 PMCID: PMC5891919 DOI: 10.1186/s13567-018-0529-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 03/21/2018] [Indexed: 02/08/2023] Open
Abstract
Marine herpesviruses are responsible for epizootics in economically, ecologically and culturally significant taxa. The recent emergence of microvariants of Ostreid herpesvirus 1 (OsHV-1) in Pacific oysters Crassostrea gigas has resulted in socioeconomic losses in Europe, New Zealand and Australia however, there is no information on their origin or mode of transmission. These factors need to be understood because they influence the way the disease may be prevented and controlled. Mortality data obtained from experimental populations of C. gigas during natural epizootics of OsHV-1 disease in Australia were analysed qualitatively. In addition we compared actual mortality data with those from a Reed–Frost model of direct transmission and analysed incubation periods using Sartwell’s method to test for the type of epizootic, point source or propagating. We concluded that outbreaks were initiated from an unknown environmental source which is unlikely to be farmed oysters in the same estuary. While direct oyster-to-oyster transmission may occur in larger oysters if they are in close proximity (< 40 cm), it did not explain the observed epizootics, point source exposure and indirect transmission being more common and important. A conceptual model is proposed for OsHV-1 index case source and transmission, leading to endemicity with recurrent seasonal outbreaks. The findings suggest that prevention and control of OsHV-1 in C. gigas will require multiple interventions. OsHV-1 in C. gigas, which is a sedentary animal once beyond the larval stage, is an informative model when considering marine host-herpesvirus relationships.
Collapse
Affiliation(s)
| | - Ika Paul-Pont
- School of Veterinary Science, University of Sydney, Camden, NSW, 2570, Australia.,Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539 CNRS/UBO/IRD/IFREMER, Institut Universitaire Européen de la Mer, Technopôle Brest-Iroise, 29280, Plouzané, France
| | - Olivia Evans
- School of Veterinary Science, University of Sydney, Camden, NSW, 2570, Australia.,Department of Agriculture and Water Resources, Canberra, ACT, 2601, Australia
| | - Paul Hick
- School of Veterinary Science, University of Sydney, Camden, NSW, 2570, Australia
| | - Navneet K Dhand
- School of Veterinary Science, University of Sydney, Camden, NSW, 2570, Australia
| |
Collapse
|
21
|
Abbadi M, Zamperin G, Gastaldelli M, Pascoli F, Rosani U, Milani A, Schivo A, Rossetti E, Turolla E, Gennari L, Toffan A, Arcangeli G, Venier P. Identification of a newly described OsHV-1 µvar from the North Adriatic Sea (Italy). J Gen Virol 2018; 99:693-703. [PMID: 29580370 PMCID: PMC5994699 DOI: 10.1099/jgv.0.001042] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The surveillance activities for abnormal bivalve mortality events in Italy include the diagnosis of ostreid herpesvirus type 1 (OsHV-1) in symptomatic oysters. OsHV-1-positive oysters (Crassostrea gigas) were used as a source for in vivo virus propagation and a virus-rich sample was selected to perform shotgun sequencing based on Illumina technology. Starting from this unpurified supernatant sample from gills and mantle, we generated 3.5 million reads (2×300 bp) and de novo assembled the whole genome of an Italian OsHV-1 microvariant (OsHV-1-PT). The OsHV-1-PT genome encodes 125 putative ORFs, 7 of which had not previously been predicted in other sequenced Malacoherpesviridae. Overall, OsHV-1-PT displays typical microvariant OsHV-1 genome features, while few polymorphisms (0.08 %) determine its uniqueness. As little is known about the genetic determinants of OsHV-1 virulence, comparing complete OsHV-1 genomes supports a better understanding of the virus pathogenicity and provides new insights into virus-host interactions.
Collapse
Affiliation(s)
- Miriam Abbadi
- Istituto Zooprofilattico Sperimentale Delle Venezie, Legnaro (PD), Italy.,Department of Biology, University of Padova, Padova (PD), Italy
| | - Gianpiero Zamperin
- Istituto Zooprofilattico Sperimentale Delle Venezie, Legnaro (PD), Italy
| | | | - Francesco Pascoli
- Istituto Zooprofilattico Sperimentale Delle Venezie, Legnaro (PD), Italy
| | - Umberto Rosani
- Department of Biology, University of Padova, Padova (PD), Italy
| | - Adelaide Milani
- Istituto Zooprofilattico Sperimentale Delle Venezie, Legnaro (PD), Italy
| | - Alessia Schivo
- Istituto Zooprofilattico Sperimentale Delle Venezie, Legnaro (PD), Italy
| | - Emanuele Rossetti
- Consorzio Cooperative Pescatori del Polesine, Scardovari (RO), Italy
| | | | | | - Anna Toffan
- Istituto Zooprofilattico Sperimentale Delle Venezie, Legnaro (PD), Italy
| | - Giuseppe Arcangeli
- Istituto Zooprofilattico Sperimentale Delle Venezie, Legnaro (PD), Italy
| | - Paola Venier
- Department of Biology, University of Padova, Padova (PD), Italy
| |
Collapse
|
22
|
Green TJ, Speck P. Antiviral Defense and Innate Immune Memory in the Oyster. Viruses 2018; 10:v10030133. [PMID: 29547519 PMCID: PMC5869526 DOI: 10.3390/v10030133] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 03/06/2018] [Accepted: 03/14/2018] [Indexed: 12/17/2022] Open
Abstract
The Pacific oyster, Crassostrea gigas, is becoming a valuable model for investigating antiviral defense in the Lophotrochozoa superphylum. In the past five years, improvements to laboratory-based experimental infection protocols using Ostreid herpesvirus I (OsHV-1) from naturally infected C. gigas combined with next-generation sequencing techniques has revealed that oysters have a complex antiviral response involving the activation of all major innate immune pathways. Experimental evidence indicates C. gigas utilizes an interferon-like response to limit OsHV-1 replication and spread. Oysters injected with a viral mimic (polyI:C) develop resistance to OsHV-1. Improved survival following polyI:C injection was found later in life (within-generational immune priming) and in the next generation (multi-generational immune priming). These studies indicate that the oyster's antiviral defense system exhibits a form of innate immune-memory. An important priority is to identify the molecular mechanisms responsible for this phenomenon. This knowledge will motivate the development of practical and cost-effective treatments for improving oyster health in aquaculture.
Collapse
Affiliation(s)
- Timothy J Green
- Centre for Shellfish Research & Department of Fisheries and Aquaculture, Vancouver Island University, Nanaimo, BC V9R 5S5, Canada.
- Department of Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia.
| | - Peter Speck
- College of Science and Engineering, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia.
| |
Collapse
|
23
|
Detection of Ostreid herpesvirus -1 microvariants in healthy Crassostrea gigas following disease events and their possible role as reservoirs of infection. J Invertebr Pathol 2017; 148:20-33. [DOI: 10.1016/j.jip.2017.05.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 04/30/2017] [Accepted: 05/08/2017] [Indexed: 02/07/2023]
|
24
|
Young T, Kesarcodi-Watson A, Alfaro AC, Merien F, Nguyen TV, Mae H, Le DV, Villas-Bôas S. Differential expression of novel metabolic and immunological biomarkers in oysters challenged with a virulent strain of OsHV-1. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2017; 73:229-245. [PMID: 28373065 DOI: 10.1016/j.dci.2017.03.025] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2016] [Revised: 03/30/2017] [Accepted: 03/30/2017] [Indexed: 06/07/2023]
Abstract
Early lifestages of the Pacific oyster (Crassostrea gigas) are highly susceptible to infection by OsHV-1 μVar, but little information exists regarding metabolic or pathophysiological responses of larval hosts. Using a metabolomics approach, we identified a range of metabolic and immunological responses in oyster larvae exposed to OsHV-1 μVar; some of which have not previously been reported in molluscs. Multivariate analyses of entire metabolite profiles were able to separate infected from non-infected larvae. Correlation analysis revealed the presence of major perturbations in the underlying biochemical networks and secondary pathway analysis of functionally-related metabolites identified a number of prospective pathways differentially regulated in virus-exposed larvae. These results provide new insights into the pathogenic mechanisms of OsHV-1 infection in oyster larvae, which may be applied to develop disease mitigation strategies and/or as new phenotypic information for selective breeding programmes aiming to enhance viral resistance.
Collapse
Affiliation(s)
- Tim Young
- Institute for Applied Ecology New Zealand, School of Science, Faculty of Health and Environmental Sciences, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand; Metabolomics Laboratory, School of Biological Sciences, The University of Auckland, Private Bag 92019, Auckland Mail Centre, Auckland 1142, New Zealand
| | | | - Andrea C Alfaro
- Institute for Applied Ecology New Zealand, School of Science, Faculty of Health and Environmental Sciences, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand.
| | - Fabrice Merien
- AUT-Roche Diagnostics Laboratory, School of Science, Faculty of Health and Environmental Sciences, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand
| | - Thao V Nguyen
- Institute for Applied Ecology New Zealand, School of Science, Faculty of Health and Environmental Sciences, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand
| | - Hannah Mae
- Cawthron Institute, 98 Halifax Street East, Private Bag 2, Nelson 7042, New Zealand
| | - Dung V Le
- Institute for Applied Ecology New Zealand, School of Science, Faculty of Health and Environmental Sciences, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand
| | - Silas Villas-Bôas
- Metabolomics Laboratory, School of Biological Sciences, The University of Auckland, Private Bag 92019, Auckland Mail Centre, Auckland 1142, New Zealand
| |
Collapse
|
25
|
Azéma P, Lamy JB, Boudry P, Renault T, Travers MA, Dégremont L. Genetic parameters of resistance to Vibrio aestuarianus, and OsHV-1 infections in the Pacific oyster, Crassostrea gigas, at three different life stages. Genet Sel Evol 2017; 49:23. [PMID: 28201985 PMCID: PMC5311879 DOI: 10.1186/s12711-017-0297-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Accepted: 02/08/2017] [Indexed: 12/11/2022] Open
Abstract
Background In France, two main diseases threaten Pacific oyster production. Since 2008, Crassostrea gigas spat have suffered massive losses due to the ostreid herpesvirus OsHV-1, and since 2012, significant mortalities in commercial-size adults have been related to infection by the bacterium Vibrio aestuarianus. The genetic basis for resistance to V. aestuarianus and OsHV-1 and the nature of the genetic correlation between these two traits were investigated by using 20 half-sib sire families, each containing two full-sib families. For each disease, controlled infectious challenges were conducted using naïve oysters that were 3 to 26 months old. In addition, siblings were tested under field, pond and raceway conditions to determine whether laboratory trials reflected mortality events that occur in the oyster industry. Results First, we estimated the genetic basis of resistance to V. aestuarianus in C. gigas. Susceptibility to the infection was low for oysters in spat stage but increased with later life stages. Second, we confirmed a strong genetic basis of resistance to OsHV-1 infection at early stages and demonstrated that it was also strong at later stages. Most families had increased resistance to OsHV-1 infection from the spat to adult stages, while others consistently showed low or high mortality rates related to OsHV-1 infection, regardless of the life stage. Our third main finding was the absence of genetic correlations between resistance to OsHV-1 infection and resistance to V. aestuarianus infection. Conclusions Selective breeding to enhance resistance to OsHV-1 infection could be achieved through selective breeding at early stages and would not affect resistance to V. aestuarianus infection. However, our results suggest that the potential to select for improved resistance to V. aestuarianus is lower. Selection for dual resistance to OsHV-1 and V. aestuarianus infection in C. gigas might reduce the impact of these two major diseases by selecting families that have the highest breeding values for resistance to both diseases. Electronic supplementary material The online version of this article (doi:10.1186/s12711-017-0297-2) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Patrick Azéma
- Laboratoire de Génétique et Pathologie des Mollusques Marins, Ifremer, avenue Mus de Loup, 17390, La Tremblade, France
| | - Jean-Baptiste Lamy
- Laboratoire de Génétique et Pathologie des Mollusques Marins, Ifremer, avenue Mus de Loup, 17390, La Tremblade, France
| | - Pierre Boudry
- Laboratoire des Sciences de l'Environnement Marin, UMR 6539 LEMAR (UBO/CNRS/IRD/Ifremer), Centre de Bretagne, Ifremer, CS 10070, 29280, Plouzané, France
| | - Tristan Renault
- Département Ressources Biologique et Environnement, Ifremer, Rue de l'Ile d'Yeu, 44300, Nantes, France
| | - Marie-Agnès Travers
- Laboratoire de Génétique et Pathologie des Mollusques Marins, Ifremer, avenue Mus de Loup, 17390, La Tremblade, France
| | - Lionel Dégremont
- Laboratoire de Génétique et Pathologie des Mollusques Marins, Ifremer, avenue Mus de Loup, 17390, La Tremblade, France.
| |
Collapse
|
26
|
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.
Collapse
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.
| |
Collapse
|
27
|
Evans O, Paul-Pont I, Whittington RJ. Detection of ostreid herpesvirus 1 microvariant DNA in aquatic invertebrate species, sediment and other samples collected from the Georges River estuary, New South Wales, Australia. DISEASES OF AQUATIC ORGANISMS 2017; 122:247-255. [PMID: 28117303 DOI: 10.3354/dao03078] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Ostreid herpesvirus 1 microvariants (OsHV-1) present a serious threat to the Australian Crassostrea gigas industry. Of great concern is the propensity for mortality due to the virus recurring each season in farmed oysters. However, the source of the virus in recurrent outbreaks remains unclear. Reference strain ostreid herpesvirus 1 (OsHV-1 ref) and other related variants have been detected in several aquatic invertebrate species other than C. gigas in Europe, Asia and the USA. The aim of this study was to confirm the presence or absence of OsHV-1 in a range of opportunistically sampled aquatic invertebrate species inhabiting specific locations within the Georges River estuary in New South Wales, Australia. OsHV-1 DNA was detected in samples of wild C. gigas, Saccostrea glomerata, Anadara trapezia, mussels (Mytilus spp., Trichomya hirsuta), whelks (Batillaria australis or Pyrazus ebeninus) and barnacles Balanus spp. collected from several sites between October 2012 and April 2013. Viral loads in non-ostreid species were consistently low, as was the prevalence of OsHV-1 DNA detection. Viral concentrations were highest in wild C. gigas and S. glomerata; the prevalence of detectable OsHV-1 DNA in these oysters reached approximately 68 and 43%, respectively, at least once during the study. These species may be important to the transmission and/or persistence of OsHV-1 in endemically infected Australian estuaries.
Collapse
Affiliation(s)
- Olivia Evans
- Faculty of Veterinary Science, School of Life and Environmental Sciences, The University of Sydney, Camden, NSW 2570, Australia
| | | | | |
Collapse
|
28
|
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.
Collapse
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
| |
Collapse
|
29
|
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.
Collapse
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
| |
Collapse
|
30
|
Detection and distribution of ostreid herpesvirus 1 in experimentally infected Pacific oyster spat. J Invertebr Pathol 2016; 133:59-65. [DOI: 10.1016/j.jip.2015.11.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 11/27/2015] [Accepted: 11/30/2015] [Indexed: 11/22/2022]
|
31
|
Whittington R, Hick P, Evans O, Rubio A, Dhand N, Paul-Pont I. Pacific oyster mortality syndrome: a marine herpesvirus active in Australia. MICROBIOLOGY AUSTRALIA 2016. [DOI: 10.1071/ma16043] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Genotypes of Ostreid herpesvirus 1 (OsHV-1) known as microvariants cause the disease Pacific oyster mortality syndrome (POMS). Since its appearance in NSW in 2010, OsHV-1 microvariant has prevented the farming of Pacific oysters (Crassostrea gigas) in the affected estuaries near Sydney, following the initial massive outbreaks1,2. The arrival of the disease in southeast Tasmania in January 2016 has put the entire $53M industry in Australia in jeopardy3. The virus is a member of the Family Malacoherpesviridae4, which includes several invertebrate herpesviruses. The OsHV-1 genome consists of 207 439 base pairs, with organisation similar to that of mammalian herpesviruses. However, OsHV-1 contains two invertible unique regions (UL, 167.8 kbp; US, 3.4 kbp) each flanked by inverted repeats (TRL/IRL, 7.6 kbp; TRS/IRS, 9.8 kbp), with an additional unique sequence (X, 1.5 kbp) between IRL and IRS4. Unlike many herpesviruses which are host specific, OsHV-1 strains have been transmitted between marine bivalve species5 and the virus is transmitted indirectly. The virus may have relatively prolonged survival in the environment, has extremely high infection and case fatality rates, and latency is unproven. Along with pilchard herpesvirus6–8 and abalone ganglioneuritis virus9,10, it is part of a dawning reality that marine herpesviruses are among the most virulent of pathogens. Finding solutions for industry requires more than laboratory-based research.
Collapse
|
32
|
|