Existence and significance of viral nonreplicative RNA recombination

Abstract

Recombination between genomes of RNA-viruses is a key actor in their micro- and macroevolution as well as in repair after genetic injuries [1,2]. Replicative and nonreplicative forms of recombination were recognized in these viruses; the former is accomplished by the viral RNA-dependent RNA polymerase (RdRp), whereas the latter is not. However, Kim and colleagues, in a recent publication in this journal [3], negated the existence of the latter mode on the basis of their discovery of a novel, noncanonical IRES-independent RNA translation in some IRES-containing viruses. They claimed that “. . . all of the studies supporting nonreplicative recombination . . . employed RNA transfection of RNAs capable of expressing the RdRp.” Although their paper indeed expands our understanding of translation initiation, the conclusion about the nonexistence of nonreplicative recombination in RNA-viruses cannot be considered accurate. Such mechanism is a real phenomenon, as convincingly shown by our laboratory and others. Importantly, a related class of reactions might be widespread in the nature, contributing to the evolution not only of viruses but of cellular organisms as well. Hence, it is appropriate to briefly summarize here the current knowledge on this process.