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Vega-Heredia S, Giffard-Mena I, Reverter M. Bacterial and viral co-infections in aquaculture under climate warming: co-evolutionary implications, diagnosis, and treatment. DISEASES OF AQUATIC ORGANISMS 2024; 158:1-20. [PMID: 38602294 DOI: 10.3354/dao03778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2024]
Abstract
Climate change and the associated environmental temperature fluctuations are contributing to increases in the frequency and severity of disease outbreaks in both wild and farmed aquatic species. This has a significant impact on biodiversity and also puts global food production systems, such as aquaculture, at risk. Most infections are the result of complex interactions between multiple pathogens, and understanding these interactions and their co-evolutionary mechanisms is crucial for developing effective diagnosis and control strategies. In this review, we discuss current knowledge on bacteria-bacteria, virus-virus, and bacterial and viral co-infections in aquaculture as well as their co-evolution in the context of global warming. We also propose a framework and different novel methods (e.g. advanced molecular tools such as digital PCR and next-generation sequencing) to (1) precisely identify overlooked co-infections, (2) gain an understanding of the co-infection dynamics and mechanisms by knowing species interactions, and (3) facilitate the development multi-pathogen preventive measures such as polyvalent vaccines. As aquaculture disease outbreaks are forecasted to increase both due to the intensification of practices to meet the protein demand of the increasing global population and as a result of global warming, understanding and treating co-infections in aquatic species has important implications for global food security and the economy.
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Affiliation(s)
- Sarahí Vega-Heredia
- Universidad Autónoma de Baja California, Facultad de Ciencias Marinas, Ensenada, México, Egresada del Programa de Ecología Molecular y Biotecnología, carretera transpeninsular Ensenada-Tijuana No. 3917, C.P. 22860, México
| | - Ivone Giffard-Mena
- Universidad Autónoma de Baja California, Facultad de Ciencias Marinas, Ensenada, México
| | - Miriam Reverter
- School of Biological and Marine Sciences, Plymouth University, Drake Circus, Devon PL4 8AA, UK
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Divilov K, Wang X, Swisher AE, Yeoman PC, Rintoul M, Fleener GB, Schoolfield B, Langdon C, Jin L. Ostreid herpesvirus 1 latent infection and reactivation in adult Pacific oysters, Crassostrea gigas. Virus Res 2024; 339:199245. [PMID: 37839558 PMCID: PMC10613911 DOI: 10.1016/j.virusres.2023.199245] [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: 08/30/2023] [Revised: 10/11/2023] [Accepted: 10/12/2023] [Indexed: 10/17/2023]
Abstract
Ostreid herpesvirus 1 (OsHV-1) is one of the most economically important pathogens of Pacific oysters. Understanding the pathogenesis of this virus is critical to developing tools to control outbreaks on shellfish farms. OsHV-1 is genetically related to vertebrate herpesviruses, which have a lytic and a latent stage, with the latent stage capable of being reactivated to the lytic stage. Here, OsHV-1 latency in Pacific oysters was investigated in experimentally and naturally infected oysters. Lytic infection in one-year-old oysters injected with the Tomales Bay strain of OsHV-1 was detectable between 1 and 4 days post-injection (dpi) but was not detectable after 5 dpi. The injected oysters shed 1 × 102 to 1 × 104 DNA copies/ml into the water during the 4-day acute phase. Lytic shedding was not detectable in two-year-old oysters injected similarly with the same strain of OsHV-1; however, the OsHV-1 genome was detectable by qPCR in the adductor muscle, gill, mantle, and hemocytes within the first 3 dpi, after which it became undetectable. No OsHV-1 was detectable in the adductor muscle, gill, or mantle from experimentally infected oysters on days 15 and 21 post-injection or from oysters sampled 9 months after surviving an OsHV-1 mortality event; however, OsHV-1 DNA could be detected in hemocytes of both experimentally infected oysters at 21 dpi and naturally infected oysters using nested PCR. In addition, lytic viral gene transcription was detectable in hemocytes of experimentally infected oysters between 1 and 21 dpi and in hemocytes of naturally infected oysters. Furthermore, OsHV-1 reactivation from latency was induced in experimentally infected oysters at 21 dpi and in naturally infected oysters 12 months after an OsHV-1 outbreak.
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Affiliation(s)
- Konstantin Divilov
- Department of Fisheries, Wildlife, and Conservation Sciences, Coastal Oregon Marine Experiment Station, Oregon State University, Hatfield Marine Science Center, Newport, OR 97365, USA
| | - Xisheng Wang
- Department of Biomedical Sciences, Carlson College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA
| | - Alexandra E Swisher
- Department of Biomedical Sciences, Carlson College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA
| | - Peyton C Yeoman
- Department of Biomedical Sciences, Carlson College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA
| | | | | | - Blaine Schoolfield
- Department of Fisheries, Wildlife, and Conservation Sciences, Coastal Oregon Marine Experiment Station, Oregon State University, Hatfield Marine Science Center, Newport, OR 97365, USA
| | - Chris Langdon
- Department of Fisheries, Wildlife, and Conservation Sciences, Coastal Oregon Marine Experiment Station, Oregon State University, Hatfield Marine Science Center, Newport, OR 97365, USA
| | - Ling Jin
- Department of Biomedical Sciences, Carlson College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA.
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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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Dégremont L, Morga B, Maurouard E, Travers MA. Susceptibility variation to the main pathogens of Crassostrea gigas at the larval, spat and juvenile stages using unselected and selected oysters to OsHV-1 and/or V. aestuarianus. J Invertebr Pathol 2021; 183:107601. [PMID: 33964304 DOI: 10.1016/j.jip.2021.107601] [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: 04/21/2020] [Revised: 04/15/2021] [Accepted: 04/25/2021] [Indexed: 10/21/2022]
Abstract
French commercial hatcheries are massively producing Crassostrea gigas selected for their higher resistance to OsHV-1, and soon should also implement selection for increasing resistance to Vibrio aestuarianus. The first objective of this study was to optimize the breeding programs for dual resistance to OsHV-1 and V. aestuarianus to determine the earliest life stage for which oysters are able to develop disease resistance. Wild stocks and selected families were tested using experimental infections by both pathogens at the larval, spat and juvenile stages. Oyster families could be evaluated for OsHV-1 as soon as the larval stage by a bath method, but this only highlighted the most resistant families; those that showed the highest resistance to V. aestuarianus could be determined using the cohabitation method at the juvenile stage. The second objective of this study was to determine if selection to increase/decrease the resistance to OsHV-1 and V. aestuarianus could have an impact on other major pathogens currently detected in hatchery at the larval stage, and in nursery and field at the spat/juveniles stages (V. coralliilyticus, V. crassostreae, V. tasmaniensis, V. neptunius, V. europaeus, V. harveyi, V. chagasi). No relationship was found between mortality caused by V. aestuarianus/OsHV-1 and the mortality caused by the other virulent bacterial strains tested regardless the stages, except between OsHV-1 and V. tasmaniensis at the juvenile stage. Finally, miscellaneous findings were evidenced such as (1) bath for bacterial challenges was not adapted for spat, (2) the main pathogens at the larval stage were OsHV-1 and V. coralliilyticus using bath, while it was V. coralliilyticus, V. europaeus, and V. neptunius at the juvenile stage by injection, and (4) variation in mortality was observed among families/wild controls for all pathogens at larval and juvenile stages, except for V. harveyi for larvae.
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Affiliation(s)
| | | | | | - Marie-Agnès Travers
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, F-34090 Montpellier, France
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Immunomodulatory and Antiviral Effects of Macroalgae Sulphated Polysaccharides: Case Studies Extend Knowledge on Their Importance in Enhancing Shellfish Health, and the Control of a Global Viral Pathogen Ostreid Herpesvirus-1 microVar. POLYSACCHARIDES 2021. [DOI: 10.3390/polysaccharides2020014] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Macroalgae are the primary source of non-animal sulphated polysaccharides (SPs) in the marine environment with fucoidans derived from brown algae (Phaeophyta) and carrageenans from red algae (Rhodophyta). Much research has been carried out on SP effects on Asian shrimp species (genera Penaeus and Metapenaeus) but their effect on commercially important bivalve mollusc species is limited and in Pacific oyster Crassostrea gigas is unknown. Knowledge of their impact on bivalve pathogens and Palaemon shrimp is unknown. The objectives of this study were to assess the effects of Fucus vesiculosus (Phaeophyta), Mastocarpus stellatus (Rhodophyta) and algal derivatives (fucoidan and κ-carrageenan) on C. gigas performance, and on ostreid herpesvirus-1 microvar (OsHV-1 μVar) and bacteria Vibrio spp. development. Both pathogens have been associated with significant oyster mortalities and economic losses globally. The effects of sulphated galactan from Gracilaria fisheri (Rhodophyta) on European common prawn Palaemon serratus, an important fishery species, was also assessed. Findings indicate a rapid and prolonged increase in total blood cell count, lysozyme (enzyme that destroys pathogens), and a difference in the ratio of blood cell types in treated individuals compared to their control counterparts. A significantly lower OsHV-1 μVar prevalence was observed in treated oysters and κ-carrageenan was found to suppress viral replication (loads), while OsHV-1 μVar was not detected in the fucoidan treated oysters from Day 8 of the 26-day trial. No antibacterial effect was observed however, the oysters did not succumb to vibriosis. These findings contribute further knowledge to macroalgae sulphated polysaccharide biotherapeutic properties, their twofold effect on animal health and viral suppression.
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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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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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Delmotte J, Chaparro C, Galinier R, de Lorgeril J, Petton B, Stenger PL, Vidal-Dupiol J, Destoumieux-Garzon D, Gueguen Y, Montagnani C, Escoubas JM, Mitta G. Contribution of Viral Genomic Diversity to Oyster Susceptibility in the Pacific Oyster Mortality Syndrome. Front Microbiol 2020; 11:1579. [PMID: 32754139 PMCID: PMC7381293 DOI: 10.3389/fmicb.2020.01579] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 06/17/2020] [Indexed: 12/13/2022] Open
Abstract
Juvenile Pacific oysters (Crassostrea gigas) are subjected to recurrent episodes of mass mortalities that constitute a threat for the oyster industry. This mortality syndrome named “Pacific Oyster Mortality Syndrome” (POMS) is a polymicrobial disease whose pathogenesis is initiated by a primary infection by a variant of an Ostreid herpes virus named OsHV-1 μVar. The characterization of the OsHV-1 genome during different disease outbreaks occurring in different geographic areas has revealed the existence of a genomic diversity for OsHV-1 μVar. However, the biological significance of this diversity is still poorly understood. To go further in understanding the consequences of OsHV-1 diversity on POMS, we challenged five biparental families of oysters to two different infectious environments on the French coasts (Atlantic and Mediterranean). We observed that the susceptibility to POMS can be different among families within the same environment but also for the same family between the two environments. Viral diversity analysis revealed that Atlantic and Mediterranean POMS are caused by two distinct viral populations. Moreover, we observed that different oyster families are infected by distinct viral populations within a same infectious environment. Altogether these results suggest that the co-evolutionary processes at play between OsHV-1 μVar and oyster populations have selected a viral diversity that could facilitate the infection process and the transmission in oyster populations. These new data must be taken into account in the development of novel selective breeding programs better adapted to the oyster culture environment.
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Affiliation(s)
- Jean Delmotte
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Montpellier, France
| | - Cristian Chaparro
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Montpellier, France
| | - Richard Galinier
- 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
| | - Bruno Petton
- LEMAR UMR 6539, Université de Bretagne Occidentale, CNRS, IRD, Ifremer, Argenton-en-Landunvez, France
| | - Pierre-Louis Stenger
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Montpellier, France
| | - Jeremie Vidal-Dupiol
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Montpellier, France
| | | | - Yannick Gueguen
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Montpellier, France
| | - Caroline Montagnani
- IHPE, Université de Montpellier, CNRS, Ifremer, Université de Perpignan Via Domitia, Montpellier, France
| | - Jean-Michel Escoubas
- 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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Xin L, Huang B, Zhang H, Li C, Bai C, Wang C. OsHV-1 infection leads to mollusc tissue lesion and iron redistribution, revealing a strategy of iron limitation against pathogen. Metallomics 2020; 11:822-832. [PMID: 30843573 DOI: 10.1039/c9mt00018f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The mass mortality of molluscs caused by OsHV-1 infection has frequently occurred worldwide in recent years. Meanwhile the interaction between OsHV-1 and its host is largely unknown. Innate immunity mainly makes up the mollusc defense system, due to the lack of adaptive immunity in invertebrates. The iron limitation strategy is an indispensable facet of innate immunity across vertebrate and invertebrate species. In this study, an iron limitation strategy was interestingly found to contribute to mollusc innate immune responses against OsHV-1 infection. Firstly, ark clams, Scapharca broughtonii, were experimentally infected with OsHV-1, and serious hyperaemia in hepatopancreases and the erosion of gills were observed post OsHV-1 infection according to a histology assay. Meanwhile, based on quantification and Prussian blue staining, the process of iron efflux from ark clams was described post OsHV-1 infection. Secondly, ferritin, as an important iron storage protein, was characterized in ark clams and showed significant iron binding activity. According to the results of an immunohistochemistry assay, ferritin was supposed to be responsible for the iron translocation in ark clams post OsHV-1 infection. Its expression level was significantly fluctuant in response to OsHV-1 infection. Finally, oxidative stress was assessed by the analyses of H2O2 content, total antioxidant capacity and MDA level post OsHV-1 infection. Supplementary iron was found to promote ROS generation and death of hemocytes in vivo. These results highlighted that microenvironment changes in the essential nutrient iron should be an important aspect of the pathogenesis of OsHV-1 disease.
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Affiliation(s)
- Lusheng Xin
- Qingdao Key Laboratory of Mariculture Epidemiology and Biosecurity, Key Laboratory of Maricultural Organism Disease Control, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Function Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, P. R. China.
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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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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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Pauletto M, Segarra A, Montagnani C, Quillien V, Faury N, Le Grand J, Miner P, Petton B, Labreuche Y, Fleury E, Fabioux C, Bargelloni L, Renault T, Huvet A. Long dsRNAs promote an anti-viral response in Pacific oyster hampering ostreid herpesvirus 1 replication. J Exp Biol 2017; 220:3671-3685. [DOI: 10.1242/jeb.156299] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 08/07/2017] [Indexed: 12/24/2022]
Abstract
Double stranded RNA-mediated genetic interference (RNAi) is a widely used reverse genetic tool for determining the loss-of-function phenotype of a gene. Here, the possible induction of an immune response by long dsRNA was tested in a marine bivalve, i.e. Crassostrea gigas, as well as the specific role of the subunit 2 of the nuclear factor κB inhibitor (IκB2). This gene is a candidate of particular interest for functional investigations in the context of massive mortality oyster events as Cg-IκB2 mRNA levels exhibited significant variation depending on the amount of ostreid herpesvirus 1 (OsHV-1) DNA detected. In the present study, dsRNAs targeting Cg-IκB2 and Green Fluorescence Protein genes were injected in vivo into oysters before being challenged by OsHV-1. Survival appeared close to 100% in both dsRNA injected conditions associated with a low detection of viral DNA and a low expression of a panel of 39 OsHV-1 genes as compared to infected control. Long dsRNA molecules, both Cg-IκB2- and GFP-dsRNA, may have induced an anti-viral state controlling the OsHV-1 replication and precluding the understanding of the Cg-IκB2 specific role. Immune-related genes including Cg-IκB1, Cg-Rel1, Cg-IFI44, Cg-PKR, and Cg-IAP appeared activated in dsRNA-injected condition potentially hampering viral replication and thus conferring a better resistance to OsHV-1 infection. We revealed that long dsRNA-mediated genetic interference triggered an anti-viral state in the oyster, emphasizing the need of new reverse genetics tools for assessing immune gene function and avoiding off-target effects in bivalves.
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Affiliation(s)
- Marianna Pauletto
- Department of Comparative Biomedicine and Food Science. University of Padova, Viale dell'Università 16, 35020 Legnaro (PD), Italy
| | - Amélie Segarra
- Ifremer, Laboratoire de Génétique et Pathologie des Mollusques Marins, 17390 La Tremblade, France
| | - Caroline Montagnani
- Ifremer, IHPE UMR 5244, Univ. Perpignan Via Domitia, CNRS, Univ. Montpellier, F-34095, Montpellier, France
| | - Virgile Quillien
- Ifremer, UMR 6539 CNRS/UBO/IRD/Ifremer, LEMAR, 29280 Plouzané, France
| | - Nicole Faury
- Ifremer, Laboratoire de Génétique et Pathologie des Mollusques Marins, 17390 La Tremblade, France
| | | | - Philippe Miner
- Ifremer, UMR 6539 CNRS/UBO/IRD/Ifremer, LEMAR, 29280 Plouzané, France
| | - Bruno Petton
- Ifremer, UMR 6539 CNRS/UBO/IRD/Ifremer, LEMAR, 29280 Plouzané, France
| | - Yannick Labreuche
- Sorbonne Universités, UPMC Paris 06, CNRS, UMR 8227, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff cedex, France
| | - Elodie Fleury
- Ifremer, UMR 6539 CNRS/UBO/IRD/Ifremer, LEMAR, 29280 Plouzané, France
| | - Caroline Fabioux
- Institut Universitaire Européen de la Mer, Université de Bretagne Occidentale, UMR 6539 CNRS/UBO/IRD/Ifremer, LEMAR, 29280 Plouzané, France
| | - Luca Bargelloni
- Department of Comparative Biomedicine and Food Science. University of Padova, Viale dell'Università 16, 35020 Legnaro (PD), Italy
| | - Tristan Renault
- Ifremer, Département Ressources Biologiques et Environnement, rue de l'Ile d'Yeu, 44000 Nantes, France
| | - Arnaud Huvet
- Ifremer, UMR 6539 CNRS/UBO/IRD/Ifremer, LEMAR, 29280 Plouzané, France
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