Continuum of Change in RNA Virus Genomes

Abstract

The mechanisms of evolution of RNA virus genomes have recently received less attention than the evolution of DNA genomes (or of RNA retroviruses able to reverse-transcribe their RNA genomes into DNA proviruses). The latter two virus groups can employ all of the myriad mutational and recombinational mechanisms of DNA evolution, which have been intensively investigated during the past decade. On the other hand the genomes of ``ordinary,'' nonretrovirus RNA viruses rarely, if ever, are reverse-copied into DNA, so they can neither integrate onto host chromosomes, nor recombine or transpose with other DNA elements. Yet the earlier studies of RNA virus genetics [1] showed that they are extremely mutable. The author and his colleagues recently published an extensive review of the literature documenting that RNA viruses not only exhibit very high mutation rates, but that their genomes undergo extremely rapid rates of evolution [2]. Space limitations prevent referencing herein most of the numerous studies upon which these conclusions are based, but the reader can obtain these from the above review.