MOLECULAR CHARACTERIZATION OF SMALL ROUND STRUCTURED VIRUSES ASSOCIATED WITH GASTROENTERITIS IN SOUTH-AFRICA

The application of the reverse transcriptase polymerase chain reaction (RT-PCR) has enabled several morphologically and physically similar s mall round structured viruses (SRSVs), including the prototype Norwalk virus (NV), to be classified within the Caliciviridae. This technique , using primers directed to the RNA-dependent RNA polymerase region wi thin the ORF1 of NV, was used to characterise SRSVs associated with ep idemic gastroenteritis in adults and sporadic paediatric gastroenterit is in South Africa. Genomic variation was investigated by sequence ana lysis of the amplified 209bp cDNA region from six isolates and compari son with other characterised SRSVs including NV. Antigenic variation w as investigated by the use of the recombinant enzyme immunoassay descr ibed recently for the detection of Snow Mountain agent-like antigen in stool specimens. Two distinct antigenic groups were evident with NV-l ike viruses associated with adult gastroenteritis, and Mexico viruslik e viruses associated with paediatric gastroenteritis. Viral isolates f rom two of the outbreaks of adult gastroenteritis showed a high degree of nucleotide sequence identity with NV, i.e., 84% and 98%, respectiv ely, whereas the paediatric isolates showed 92-95% sequence similarity with the Snow Mountain-like virus, MxV. These data show concordance b etween antigenic and genomic analyses. (C) 1995 Wiley-Liss, Inc.