Interaction between the Pacific oyster Crassostrea gigas and the Ostreid herpesvirus OsHV-1 : influence of salinity and pH
Crassostrea gigas is the most cultivated oyster species around the world. Since 2008, mass mortality events have been affecting oysters aged less than one year old in Europe, and Oceania and have been associated with a new variant of the ostreid herpesvirus type 1, OsHV-1 μvar. Oysters live in estua...
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Other Authors: | , , , , |
Format: | Doctoral or Postdoctoral Thesis |
Language: | French |
Published: |
HAL CCSD
2016
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Subjects: | |
Online Access: | https://tel.archives-ouvertes.fr/tel-01673826 https://tel.archives-ouvertes.fr/tel-01673826/document https://tel.archives-ouvertes.fr/tel-01673826/file/These-2016-EDSM-Biologie_marine-FUHRMANN_Marine.pdf |
Summary: | Crassostrea gigas is the most cultivated oyster species around the world. Since 2008, mass mortality events have been affecting oysters aged less than one year old in Europe, and Oceania and have been associated with a new variant of the ostreid herpesvirus type 1, OsHV-1 μvar. Oysters live in estuaries and bays where they are exposed to fluctuations of salinity and pH. In the present work, the effect of salinity (10, 15, 25, 35 ‰) and pH (7.8, 8.1) on the response of oysters to infection by OsHV-1 was investigated. The survival of oysters acclimated to 10 ‰ prior to be exposed to a source of infection is 95% and is explained by a reduction of OsHV-1infectivity. In contrast, the survival of non-acclimated oysters simultaneously submitted to a salinity stress at 10 ‰ and exposed to a source of infectious is only 23%, likely reflecting physiological impairment. The survival (S) of oysters in other salinity treatment is ranked as follow: S15‰ > S35‰ > S25‰ and according to pH as follows: SpH 7.8 < SpH 8.1. In both studies these contrasts of survival are not explained by differences in OsHV-1 infectivity but in host metabolic response. The carbohydrate metabolism and antioxidant activity of oysters acclimated to 25 and 35‰ is higher than in oysters at 10-15 ‰ and could explain the lower survival. Lower antioxidant activity is observed in oysters maintained at pH 7.8 likely reflecting a reduced production of reactive oxygen species and the maintenance of a basal production of nitrogen reactive species despite infection. This might impair the defense ability of oysters to OsHV-1 explaining the reduced survival at pH 7.8 in comparison to what observed at pH 8.1. Crassostrea gigas est l’espèce d’huître la plus cultivée au monde. Depuis 2008, des évènements de mortalité massive touchent les huîtres âgées de moins d’un an en Europe et en Océanie et ont été associés à l’émergence d’un nouveau variant de l’Ostréid herpèsvirus type 1, OsHV-1 μvar. Les huîtres sont naturellement présentes dans les écosystèmes ... |
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