Case study of vertical transmission of ostreid herpesvirus-1 in Pacific oysters and biosecurity management based on epidemiological data from French, New Zealand and Australian hatchery-propagated seed

In recent decades, mortality caused by ostreid herpesvirus (OsHV-1)and a variant (OsHV-1μvar) has severely impacted the productionof Pacific oyster, Crassostrea gigas, chronologically in France, NewZealand (NZ) and Australia (Jenkins et al., 2013; Keeling et al., 2014;Segarra et al., 2010). This study was conceived based on observationsmade in several commercial hatcheries and research institutesin these countries where vertical transmission of OsHV-1μvar hasbeen absent or extremely rare. We have collated data from the productionof Pacific oysters across these countries to assess the riskassociated with breeding oysters from broodstock grown in OsHV-1μvar-infectedwaters. The aim is to provide a reference point forregulatory authorities to use when developing or updating biosecuritymanagement policy associated with the hatchery production ofPacific oysters