Influence of low temperatures on the survival of the Pacific oyster (Crassostrea gigas) infected with Ostreid herpesvirus type 1

Type Article
Date 2015-08
Language English
Author(s) Pernet FabriceORCID1, Tamayo David1, 2, Petton Bruno3
Affiliation(s) 1 : IFREMER, UMR LEMAR UBO CNRS IRD Ifremer 6539, F-29280 Plouzane, France.
2 : Univ Pais Vasco Euskal Herriko Unibertsitatea, Fac Ciencia & Tecnol, Dept GAFFA Anim Physiol, Bilbao 48080, Spain.
3 : IFREMER, UMR LEMAR UBO CNRS IRD Ifremer 6539, F-29840 Argenton En Landunvez, France.
Source Aquaculture (0044-8486) (Elsevier Science Bv), 2015-08 , Vol. 445 , P. 57-62
DOI 10.1016/j.aquaculture.2015.04.010
WOS© Times Cited 18
Keyword(s) Bivalve, Disease, OsHV-1, Oyster, Temperature, Virus
Abstract Mortalities of oyster seed of Crassostrea gigas associated with ostreid herpes virus OsHV-1 μVar have been observed in many oyster producing countries since 2008. The objective of this study was to further investigate whether low temperature treatments can offer a viable option to mitigate oyster mortalities. An experiment was set-up to further evaluate the effect of low temperature treatments (10 and 13°C vs. 21°C) and their duration (6 d to 83 d) on the survival of oysters previously infected with OsHV-1 μVar by means of exposure to field conditions in areas where mortalities were occurring. Average survival of oysters infected with OsHV-1μVar was 71% after 83 d at low temperatures compared to only 23% in controls maintained at 21°C. During cold-exposure, levels of OsHV-1 DNA in oyster tissues gradually decreased, down to nearly the detection limit after 24 d. However, when cold-acclimated oysters were suddenly exposed at 21°C in the laboratory, they exhibited high levels of mortality along with an enhancement of OsHV-1 DNA concentration in their tissues. Therefore, OsHV-1 persists in oysters even at low temperature and is reactivated during subsequent thermal elevation to 21°C. Low temperature treatments did not improve overall survival of oyster seed infected with OsHV-1. These results suggest that moving infected oysters to a cooler area only delays mortality and may increase the risk of infection in neighbouring stocks when rising temperatures become permissive for viral replication.
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