Evolution and Taxonomy of Positive-Strand RNA Viruses. Implications of Comparative Analysis of Amino Acid Sequences.
Crit Rev Biochem Molec Biol 28:546-547
"The grouping revealed by phylogenetic analysis may provide the basis for revision of virus classification, and a phylogenetic taxonomy of positive-strand RNA viruses is outlined. Some of the phylogenetically-derived divisions of positive-strand RNA viruses include also double-stranded RNA viruses indicating that in certain cases the type of genome nucleic acid may not be a reliable taxonomical criterion for viruses.
Hypothetical evolutionary scenarios for positive-strand RNA viruses are proposed. It is hypothesised that all positive-strand RNA viruses and some related double-stranded RNA viruses could have evloved from a common ancestor virus that contained genes for RNA-dependent RNA polymerase, a chymotrypsin-related protease that functioned also as the capsid protein, and possibly an RNA helicase."