7 more publications related to VIVALDI activities released in 2018

Spanish, English, Norwegian and French researchers involved in VIVALDI have recently published 7 articles emphasising some key scientific results obtained thanks to our project.

Manuscript: Rapid capture and detection of ostreid herpesvirus-1 from Pacific oyster Crassostrea gigas and seawater using magnetic beads (Anna Toldrà, Karl B. Andree, Edgar Bertomeu, Ana Roque, Noèlia Carrasco, Ignasi Gairín, M. Dolores Furones, Mònica Campàs)

Published in Plos One, 2018, doi: 10.1111/raq.12246

VIVALDI partner involved: IRTA

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) were used to capture viable OsHV-1 from oysters and seawater. The experiments confirmed 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.

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Manuscript: Marteilia refringens and Marteilia pararefringens sp. nov. are distinct parasites of bivalves and have different European distributions (R. Kerr, G. M. Ward, G. D. Stentiford, A. Alfjorden, S. Mortensen, J. P. Bignell, S.W. Feist, A. Villalba, M. J. Carballal, A. Cao, I. Arzul, D. Ryder and D. Bass)

Published in Parasitology, 2018, DOI: 10.1017/S003118201800063X

VIVALDI partner involved: CEFAS, IFREMER, IMR

The genetic distinctiveness between two species of a parasite, Marteilia refringens, was demonstrated in this study, which formally defines as separate species: M. refringens, which tends to infect flat oysters, and Marteilia pararefringens, which tends to infect mussels.

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Manuscript: Vibrio tapetis displays an Original Type IV Secretion System in Strains Pathogenic for Bivalve Molluscs (Graciela M. Dias, Adeline Bidault, Patrick Le Chevalier, Gwenaëlle Choquet, Clio Der Sarkissian, Ludovic Orlando, Claudine Medigue, Valerie Barbe, Sophie Mangenot, Cristiane C. Thompson, Fabiano L. Thompson, Annick Jacq, Vianney Pichereau  and Christine Paillard)

Published in Frontiers of Microbiology, 2018, DOI: 10.3389/fmicb.2018.00227

VIVALDI partner involved: CNRS

Comparative genome analysis makes it possible to determine the factors involved in host-pathogen interaction, in particular the relationship between the pathogen Vibrio tapetis and its host mollusc Venerupis philippinarum (clam). This analysis confirmed the presence of a secretion system (T4SS), which plays a central role in host adaptation and virulence. To date, this study is the first to describe the complete T4SS secretion system in pathogenic vibrio molluscs.

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Manuscript: Temperature modulate disease susceptibility of the Pacific oyster Crassostrea gigas and virulence of the Ostreid herpesvirus type 1 (Lizenn Delisle, Bruno Petton, Jean François Burguin, Benjamin Morga, Charlotte Corporeau, Fabrice Pernet)

Published in Fish and Shellfish Immunology, 2018, DOI: /10.1016/j.fsi.2018.05.056

VIVALDI partner involved: IFREMER

Oyster mortalities associated with the Ostreid herpesvirus type 1 (OsHV-1) have occurred seasonally in Europe when the seawater temperature range reaches 16–24 °C. This study assesses how temperature modulates oyster susceptibility to OsHV-1 and pathogen virulence. Oysters were injected with OsHV-1 suspension incubated at 21 °C, 26 °C and 29 °C and were placed in cohabitation with healthy oysters (recipients) at these 3 temperatures. The major result of this study is that oysters exposed to the virus at 29 °C survived much better (85.7% survival) than at 21 °C and 26 °C (52.4% and 43.9% respectively), reflecting changes in host susceptibility and/or virus virulence.

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Manuscript: Ecologically realistic model of infection for exploring the host damage caused by Vibrio aestuarianus (Leila Parizadeh, Delphine Tourbiez, Céline Garcia, Philippe Haffner, Lionel Dégremont, Frédérique Le Roux and Marie-Agnès Travers)

Published in Environmental Microbiology, 2018, DOI: 10.1111/1462-2920.14350

VIVALDI partner involved: IFREMER

The increase in frequency of oyster mortality outbreaks associated with the presence the bacteria V. aestuarianus causes since 2012 ineluctable losses for the farmers because this disease affects the adult stage of the animal. To understand the interaction between the pathogen V. aestuarianus and its host, the Pacific oyster, we developed a new "ecologically-realistic" infection model based on experimental immersion. This protocol allowed us to describe the localisation and tissular consequences of this bacteria.

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Manuscript: Oyster Farming, Temperature, and Plankton Influence the Dynamics of Pathogenic Vibrios in the Thau Lagoon (Carmen LOPEZ-JOVEN, Jean.Luc Rolland, Phylippe Haffner, Audrey Caro, Cécile Roques, Claire Carré, Marie-Agnès Travers, Eric Abadie, Mohamed Laabir, Delphine Bonnet and Delphine Destoumieux-Garzon)

Published in Frontiers of Microbiology, 2018, DOI: soon available

VIVALDI partner involved: CNRS, IFREMER

Various vibrio species have been associated with recurrent mass mortalities of juvenile oysters Crassostrea gigas, threatening oyster farming worldwide. However, the ecology of pathogens in affected oyster farming areas remains scarcely known, which limits our capacity to predict and mitigate disease occurrence. To address this issue, we monitored Vibrio species potentially pathogenic to C. gigas in 2013 and 2014 in the Thau Lagoon, a major oyster farming region in the coastal French Mediterranean. Sampling stations were chosen inside and outside the oyster farms. The abundance of Vibrio species in the water column was similar inside and outside oyster farms, suggesting important spatial dispersion of pathogens in surrounding areas. The results of the study also suggest that a winter reservoir of pathogenic vibrios could contribute to their ecology in this Mediterranean shellfish farming ecosystem.

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Manuscript: Immune-suppression by OsHV-1 viral infection causes fatal bacteraemia in Pacific oysters (Julien de Lorgeril, Aude Lucasson, Bruno Petton, Eve Toulza, Caroline Montagnani, Camille Clerissi, Jeremie Vidal-Dupiol, Cristian Chaparro, Richard Galinier, Jean-Michel Escoubas, Philippe Haffner, Lionel Dégremont Guillaume M. Charrière, Maxime Lafont, Abigaïl Delort, Agnes Vergnes, Marlène Chiarello, Nicole Faury, Tristan Rubio, Marc A. Leroy, Adeline Pérignon, Denis Régler, Benjamin Morga, Marianne Alunno-Bruscia, Pierre Boudry, Frédérique Le Roux, Delphine Destoumieux-Garzόn, Yannick Gueguen, Guillaume Mitta)

Published in Nature Communications, 2018, DOI : 10.1038/s41467-018-06659-3

VIVALDI partner involved: CNRS, IFREMER

Infectious diseases are influenced by many interacting host and environmental factors. By addressing the complexity of these interactions, we better understand the process underlying Pacific oyster mortality syndrome affecting juveniles of Crassostrea gigas, the main oyster species exploited worldwide. Using experimental infections reproducing the natural route of infection and combining thorough molecular analyses of oyster families with contrasted susceptibilities, we demonstrate that the disease is caused by multiple infections with an initial step of infection by the Ostreid herpesvirus OsHV-1μVar and in a second phase, infection by opportunistic bacteria.