Expression and Tropism of the Ostreid Herpesvirus 1 in two tissues of the Pacific oyster Crassostrea gigas

The Ostreid Herpesvirus-1 (OsHV-1) causes high mortalities in Crassostrea gigas cultures, it has been studied extensively in order to understand its pathogenesis, however, where it prefers to replicate its genes and where to remain as an active virus has not been studied. Therefore, the aim of the present work was to evaluate the expression (mRNA) and the gene (gDNA) of the viral DNA polymerase in two Crassostrea gigas infected tissues. An infection bioassay was performed to collect gill and mantle tissue to extract DNA and RNA at different hours post infection. Changes on the expression of the DNA polymerase gene was quantified by qPCR and changes in tissue were detected by histology techniques. We detected that the OsHV-1 replicates its DNA in gills, since a 59-fold higher expression of the DNA polymerase than the detection of the gene was evident. In mantle cells the virus prefers to be infecting rather than express its DNA evidenced by a 39-fold increase detected in these tissue. The results obtained suggests that the OsHV-1 replicates its DNA in gills and prefers to be as an active virus in mantle.