This study was performed to develop a passive sampling methodology for the detection of two viruses in seawater in the area of shellfish production, the norovirus (NoV), a human pathogen implicated in gastroenteritis outbreaks linked to oyster consumption and the ostreid herpesvirus type 1 (OsHV-1), a virus associated with mass mortalities of Pacific oysters.
Methods and Results
Commercially, membranes were tested for their capacity to adsorb virus: zetapor, gauze, nylon, low-density polyethylene (LDPE) and polyvinylidene difluoride (PVDF). Laboratory exposures of membranes to contaminated water samples (stool, sewage, seawater) were performed. Our data show that the amount of NoV GII genome per membrane measured with qRT-PCR increased with the time of exposure up to 24 h, for all types of membranes except gauze. After 15 days of exposure, the amount of NoV GII per membrane continued to increase only for nylon and LDPE. The amount of OsHV-1 per zetapor membrane was significantly increased as soon as 4 h of exposure, and after 24 h of exposure for all types of membranes. Exposure of membranes to serial dilutions of various samples revealed that the amount of NoV GII and OsHV-1 per membrane is significantly higher in diluted samples. The detection of NoV and OsHV-1, respectively, with zetapor and PVDF membranes was found to be more efficient than the direct analysis of sewage and seawater.
All membranes immersed in contaminated samples adsorbed NoV GII and OsHV-1. The amount of both viruses increased with the time of exposure. Zetapor and PVDF membranes seem to be more adapted to NoV GII and OsHV-1 detection respectively.
Significance and Impact of the study
Membranes tested will be used as passive samplers to improve the detection of virus in oyster production areas. Also, passive samplers could be a valuable tool for microbiome analysis with new generation sequencing.
F. Vincent-Hubert, B. Morga, T. Renault, F.S. Le Guyader, Journal of Applied Microbiology, In press, 17 February 2017