Fig. 4.
Outline of poliovirus recombination. (A) Stepwise outline of the generation of a recombinant genome from two parental genomes. (1) A cell is infected with two genomes harboring sequence differences. (2) The RdRp of poliovirus, 3Dpol, begins to replicate one of the genomes. (3) 3Dpol transfers over to a new template from a differing genome without aborting replication, producing a genomic copy that contains sequences from both templates. (4) The final product yields a new genome distinct from the parental material. (B) Mechanism of recombination-mediated avoidance of lethal mutagenesis as compared between wild type and a recombination-deficient mutant (L420A) as suggested by Kempf et al. [83]. Despite only having initially nonviable genomes, wild type virus can establish entirely viable genomes via recombination between nonviable material. With a mutant polymerase that exhibits greatly reduced recombination rates, the generation of viable offspring is limited.
Panel (A): Adapted from B.J. Kempf, et al., Picornavirus RNA recombination counteracts error catastrophe, J. Virol. 93 (14) (2019).