Interaction of viral haplotypes and oyster hemocytes during OsHV-1 μVar infection

HémoVir, Ifremer inter center, 2018
Thanks to the work carried out for many years within the LGPMM (Unit SG2M) and more recently within IHPE, the overriding role played by the OsHV-1 virus (Malacoherpesviridae) in triggering massive oyster mortalities has been demonstrated. This work has also revealed significant viral diversity (structural variants and assembly of haplotypes) both spatially and temporally. The purpose of the HemoVir project is to determine the role of haplotype assemblages in triggering and progression of the disease. The project is organized in three tasks. The first task is to determine the role of oyster hemolymph in the transmission of infection. The second task will be to identify which hemocyte populations are infected by the virus. Finally, the third task will focus on the evolution of viral haplotypes within an oyster during the infection of susceptible animals. For this, two susceptible families of oysters will be infected with the same viral preparation. After 24 hours of infection (before the animals’ death), some of the animals will be sacrificed to analyze, at the individual level, the haplotype composition of OsHV-1 μVar; the other part will be kept for tracking mortality. The comparative analysis of the haplotypes present in the viral inoculum and in the different oysters after 24 hours of infection will lead us to determine whether the assemblages of viral haplotypes vary according to the genetic background of the host individuals.