EPIDEMIOLOGIC APPLICATIONS OF NOVEL MOLECULAR METHODS TO DETECT AND DIFFERENTIATE SMALL ROUND STRUCTURED VIRUSES (NORWALK-LIKE VIRUSES)

The molecular epidemiology of a large, multistate outbreak of oyster-a ssociated gastroenteritis [Kohn et al. (1995): Journal of the American Medical Association 273:466-471. Dowell et al. (1995): Journal of Inf ectious Diseases 171:1497-1503.] was examined using new methods to det ect small round structured viruses (SRSVs) by reverse transcription-po lymerase chain reaction (RT-PCR) and to characterize strains by Southe rn hybridization and nucleotide sequencing of 81-bp of a PCR product a mplified from the RNA polymerase gene. Of 37 stool specimens examined from patients in eight clusters of the multistate outbreak, 32 (86%) g ave RT-PCR products specific for SRSVs of P1-A phylogenetic group. Nin eteen PCR products from the eight clusters were confirmed to have the identical sequence, indicating that this large outbreak was attributed to a single strain of SRSV. In one of the eight clusters, five (63%) of eight patients had a mixed infection with a second SRSV strain that belonged to P2-B phylogenetic group. Of 12 specimens from patients in five other outbreaks and one sporadic case which occurred at the same time as the multistate outbreak, 10 (83%) gave products specific for SRSVs representing four phylogenetic groups (P1-A, P1-B, P2-A, and P2- B). The sequences of the P1-A products from two outbreaks and that of the P2-B product from another outbreak were identical to the P1-A sequ ence from the eight clusters and the P2-B sequence from the one cluste r of the multistate outbreak, respectively. These results demonstrate the first application of these methods to enhance our understanding of the molecular epidemiology of SRSVs and provide answers of public hea lth interest that could not have been obtained using classical epidemi ologic methods alone. (C) 1995 Wiley-Liss, Inc.