Use of anionic polymer-coated magnetic beads to pre-concentrate Ostreid Herpesvirus 1 from seawater: Application to a UV disinfection treatment

Abstract

Ostreid Herpesvirus 1 (OsHV-1) represents a serious threat to shellfish aquaculture worldwide. To minimise its impact, early warning systems able to detect the virus in seawater prior to infection of oysters are of utmost importance. However, monitoring OsHV-1 in seawater is challenging because of its presence at very low concentrations. Thus, a rapid and simple method to pre-concentrate the virus is needed to enable detection. Herein, magnetic beads (MBs) coated with an anionic polymer were used to pre-concentrate OsHV-1 from biological matrices including oyster homogenate and seawater samples. Following virus capture, OsHV-1 DNA detection was performed by quantitative PCR (qPCR). The MB-based approach combined with qPCR attained a limit of detection (LOD) as low as 0.1 viral copy/μL, which was 100 times lower than that of the qPCR alone. This approach was applied to the analysis of OsHV-1 in seawater from an Enhanced Hydro-Optic UV (HOD-UV) disinfection experiment operating at a UV dose of 1360 J/m2 in an open flow system. Our approach enabled detection of the virus in non-treated seawater and not in UV-treated seawater, discrimination that was not possible using qPCR alone. Moreover, the strategy provided data on the pattern of kinetics of the release of the virus in seawater. The approach could find applications in shellfish hatcheries and depuration plants to ensure biosecurity requirements.