Experimental herpes-like viral infections in marine bivalves: demonstration of interspecies transmission

Since 1972, herpes-like virus infections have been reported in several mari ne bivalve species around the world. Viral detection was often associated w ith high mortality rates in larvae and spat. To determine whether a single virus is able to infect different bivalve host species, we carried out expe rimental transmission assays. As a first step, 8 assays were performed to i nfect axenic Crassostrea gigas larvae with virus from infected C. gigas lar vae using a previously described protocol. The protocol appeared reliable a nd PCR was confirmed as a powerful technique for detecting viral DNA in exp erimentally infected oysters. The defined protocol was then applied to infe ct different bivalve species. Interspecies viral transmission was demonstra ted under laboratory conditions. The same phenomenon may occur in private h atcheries and may be promoted by intensive rearing conditions. This hypothe sis is reinforced by reports of concomitant mortalities in the larvae of se veral bivalve species and by the first molecular analysis of infected larva l samples.