Virulence of Ostreid herpesvirus 1 μVar in sea water at 16°C and 25°C
2015
Martenot, Claire | Denechère, Lucie | Hubert, Paul | Metayer, Laetitia | Oden, Elise | Trancart, Suzanne | Travaillé, Emmanuelle | Houssin, Maryline
The Ostreid herpesvirus 1 (OsHV-1) is associated with the mortality of young oysters Crassostrea gigas in France. The virus could infect different marine bivalve species and OsHV-1 DNA was previously detected in crustacean, marine gastropod, and sediment. Nevertheless, the effect of the temperature on the stability of infectious viral particles in sea water remains unpublished. During a mortality event, dead oysters may release virus in the sea water such as free viral particles, viral particles included in cells or attached to a support like plankton, suspended particulate matters, and microalgae. Oysters placed around the infectious source may filtrate the virus and then be infected by OsHV-1. In the present study, we investigated the OsHV-1 μVar virulence in sea water at 16°C and 25°C. Filtered infected tissue homogenates were kept at 16°C or 25°C prior to injection challenge of uninfected spats. A real-time reverse transcription PCR targeting the OsHV-1 polymerase gene has been developed to confirm the death cause oysters collected during the experiment. The RNA detection of herpesvirus in their hosts is a sign of viral replication and indicates that the virus is certainly infectious. Results showed that the OsHV-1 μVar remained infectious and induced mortality after 33h at 25°C and 54h at 16°C in controlled conditions. The OsHV-1 μVar is thus able to persist in sea water and high temperatures seem to reduce its infectivity. However, the OsHV-1 μVar virulence may be modulated by biological, physical and chemical factors which are present in sea water.
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