An investigation into the detection and identification of OsHV-1 µvar virus and associated risk factors causing mortalities in Crassostrea gigas in Ireland.

Abstract

The Oyster Herpes Virus micro variant, OsHV-1μvar, is an emerging disease affecting Crassostrea gigas oysters which has caused significant mortalities in France, Ireland, and the UK (Jersey and Kent, England) between the summer of 2008 and 2012.The present MSc. study was carried out in 2 parts. The first part of the study aimed to characterize and further elucidate the strains of OsHV-1 present in C. gigas oysters sampled in Ireland by further examining sequence data obtained from animals collected from 30 bays during mortality outbreaks between 2003-2012. Part two of this study investigated the detection of OsHV-1 µvar and associated risk factors during mortality outbreaks. The current study provides some insights into mortality events affecting farmed Pacific oyster production in Ireland. The epidemiological study conducted found that batch mortality was lower in 2011, compared with earlier years, in association with lower OsHV-1 µvar viral loads.