Molecular Aspects of the Antigenic Variation of Swine Vesicular Disease and Coxsackie B5 Viruses

SUMMARY The antigenic variation of swine vesicular disease virus (SVDV) and Coxsackie B5 virus (CB5) has been examined at the molecular level by analysing the protein and nucleic acid of the virus particles. The tryptic peptides of carboxymethylated 35S-methionine labelled virus particles were very similar, although some minor differences were apparent. Competition hybridization experiments confirmed that there is variation in the RNA sequence of antigenically distinct SVD viruses and some limited homology of these RNAs to the CB5 virus RNAs. Competition hybridization using mixtures of two RNAs as competitors showed that the sequences shared by the CB5 virus RNAs were largely the same as those shared by the CB5 virus RNAs and the SVDV RNAs. Similar experiments with the SVDV RNAs established that the homologous regions in these RNAs were also shared. Thermal denaturation curves of SVDV RNA-RNA hybrids generally supported the competition hybridization results but the hybrids between SVDV RNA and CB5 virus RNA were shown to be mismatched. Ribonuclease T1 oligonucleotide maps of the virus RNAs were also compared to obtain another measure of relatedness. A number of long oligonucleotides were shared by the SVDV RNAs but few of these were found in either of the CB5 RNAs. Further ways of investigating the antigenic variation of SVDV at the molecular level are discussed.