Nonreplicative RNA recombination in poliovirus

Current models of recombination between viral RNAs are based on replicative template-switch mechanisms. The existence of nonreplicative RNA recombinat ion in poliovirus is demonstrated in the present study by the rescue of via ble viruses after cotransfections with different pairs of genomic RNA fragm ents with suppressed translatable and replicating capacities. Approximately 100 distinct recombinant genomes have been identified. The majority of cro ssovers occurred between nonhomologous segments of the partners and might h ave resulted from transesterification reactions, not necessarily involving an enzymatic activity. Some of the crossover loci are clustered. The origin of some of these "hot spots" could be explained by invoking structures sim ilar to known ribozymes, A significant proportion of recombinant RNAs conta ined the entire 5' partner, if its 3' end was oxidized or phosphorylated pr ior to being mixed with the 3' partner. All of these observations are consi stent with a mechanism that involves intermediary formation of the 2',3'-cy clic phosphate and 5'-hydroxyl termini, It is proposed that nonreplicative RNA recombination may contribute to evolutionarily significant RNA rearrang ements.