Monitoring the marine environment for small round structured viruses (SRSVS): A new approach to combating the transmission of these viruses by molluscan shellfish

This study investigates human enteric virus contamination of a shellfish ha rvesting area. Samples were analysed over a 14-month period for Small Round Structured Viruses (SRSVs) using a previously developed nested RT-PCR. A c lear seasonal difference was observed with the largest numbers of positive samples obtained during the winter period (October to March). This data con curs with the known winter association of gastroenteric illness due to oyst er consumption in the UK and also with the majority of the outbreaks associ ated with shellfish harvested from this area during the study period. RT-PC R positive amplicons were further characterised by cloning and sequencing. Sequence analysis of the positive samples identified eleven SRSV strains, o f both Genogroup I and Genogroup II, occurring throughout the study period. Many shellfish samples contained a mixture of strains with a few samples c ontaining up to three different strains with both Genogroups represented. T he observed common occurrence of strain mixtures may have implications for the role of shellfish as a vector for dissemination of SRSV strains. These results show that nested RT-PCR can identify SRSV contamination in shellfis h harvesting areas. Virus monitoring of shellfish harvesting areas by speci alist laboratories using RT-PCR is a possible approach to combating the tra nsmission of SRSVs by molluscan shellfish and could potentially offer signi ficantly enhanced levels of public health protection. (C) 1998 IAWQ Publish ed by Elsevier Science Ltd. All rights reserved.