COMPARATIVE STUDIES ON THE GENOMES OF SOME PICORNAVIRUSES - DENATURATION MAPPING OF REPLICATIVE FORM RNA AND ELECTRON-MICROSCOPY OF HETERODUPLEX RNA

Methods for denaturation mapping of double-stranded RNA and for heteroduplex RNA analysis are described. Denaturation maps of encephalomyocarditis (EMC) virus, poliovirus type 1, and poliovirus type 3 replicative form RNAs are presented. The three maps possess distinct features. Electron microscopy of heteroduplex RNA molecules constructed from poliovirus type 1 and poliovirus type 3 complementary RNA chains reveals two regions of considerable nonhomology as well as relatively conserved regions. The position of loops in this heteroduplex roughly corresponds to the location of regions where the denaturation maps of two polioviruses differ from each other. There is no evidence indicating that differences in the RNA sequences of poliovirus type 1 and poliovirus type 3 are due to extensive deletions (insertions) of genetic material; rather, the evolutionary divergence of these viruses seems to result, at least largely, from point mutations or equal substitutions. © 1979.