Mechanisms of viral emergence

Domingo, Esteban

Recombination occurs both with RNA and DNA viruses, but it is infrequent with most negative-strand RNA viruses. Recombination has been divided in replicative and non-replicative, according to whether viral genome replication is required or not [9, 29] . From the point of view of evolution, recombination has been viewed as a means to rescue fit viral genomes from low fitness parents (a force to eliminate deleterious mutations) or a means to produce highly divergent genomes that provide an opportunity to explore the adaptative potential of rare genomic combinations (a force for large evolutionary transitions). There is good evidence that recombination and reassortment events, followed by fitness adjustments through mutation, have played a role in the emergence and re-emergence of new viral pathogens. In fact, most (but not all) emergences Table I . Some biological implications of the quasispecies nature of RNA viruses.