Intratypic recombination of polioviruses: evidence for multiple crossing-over sites on the viral genome.

Intratypic recombinant polioviruses were isolated from cells that were coinfected with two temperature-sensitive (ts) mutants of poliovirus type 1, ts035Gr and ts247. After phenotypic characterization of these recombinants, their proteins were studied by polyacrylamide gel electrophoresis, and their genomes were analyzed by RNase T1 fingerprinting and partial nucleotide sequencing. Segregation of specific phenotypic and biochemical characteristics inherited from the parental viruses demonstrated that crossing-over could occur in at least four distinct regions of the genome. Possible mechanisms for recombination are discussed.