Effects of high-pressure processing on murine norovirus-1 in oysters (Crassostrea gigas) in situ

We assessed the effects of high-pressure processing (HPP) at 200–400 MPa on murine norovirus-1 (MNV-1)-contaminated oysters by using a flow-through seawater system. Plaque assays demonstrated that a 5-min 400-MPa treatment at 0 °C inactivated MNV-1 within oysters to undetectable levels. No correlation was found between MNV-1 RNA detection by reverse transcription-PCR (RT-PCR) and the infectivity determined by the plaque assay before and after pressure exposure. Pretreatment with proteinase K and RNase A enabled the differentiation between infectious and HPP-inactivated MNV-1 by RT-PCR, indicating that HPP might subtly alter the viral capsid proteins but that the RNA remains protected.