||Gay Melanie, Renault Tristan, Le Roux Frédérique
||95. Annual Meeting of the National Shellfisheries Association, New Orleans, LA (USA), 13-17 Apr 2003
||Vibrio splendidus, Vibrio lentus, Crassostrea gigas, Summer, Spat, Pathogen, Disease transmission, Oyster culture, Mortality, Microbial contamination, Oysters
||The pathogens related to summer mortality outbreaks are a herpes virus and two bacterial strains one belonging to Vibrio splendidus biovar II and the other to Vibrio splendidus spp. However, the feature pathogen/opportunist of these strains is still unknown. Several strains belonging to the genus Vibrio have been identified as pathogen for different mollusk species. In the context of the French program Morest, experiments of cohabitation have been used to demonstrate the potential presence of a transmissible infectious agent in batches of oysters suffering from summer mortality outbreaks. More than one hundred Vibrio strains have been isolated from these experiments. These strains have been phenotypically and genotypically characterized. Their virulence has been evaluated by infection trials. Two Vibrio lentus strains have been selected. The mortality rate induced by them injected together is always higher than the mortality rate induced by each strain injected individually. A histological examination of injected animals showed damaged hemocytes and muscle. However, bacteria have only been observed in the tissue surrounding the muscle and in the kidney. We have shown that physiological and genetic factors had an effect on the sensitivity of Crassostrea gigas to the experimental model of bacterial infections.