RNA Virus Populations as Quasispecies

Abstract
This chapter discusses the high mutation frequencies and rapid evolution potential of RNA viruses. The concepts discussed are applicable to all “ordinary” RNA viruses (riboviruses), viroids and satellite RNAs; to retroviruses; and to viruses (such as the hepadnaviruses) with DNA genomes which replicate via RNA transcripts. Because DNA virus polymerases can have proofreading (Kornberg 1974), their mutation frequencies can be much lower than those of RNA viruses. For example, the mutation rate of bacteriophage T4 approximates 10−8 per base pair per replication (Drake 1969). However, some DNA viruses may avoid high-fidelity replication mechanisms (Drake et al. 1969; Hall et al. 1984) to gain the evolutionary advantages of high mutation frequencies (Smith and Inglis 1987).