Fate of mismatched base-pair regions in polyoma heteroduplex DNA during infection of mouse cells.

Heteroduplex DNA has been constructed from two variants of polyoma virus that differ genotypically at four distinct sites. The genotypes of the progeny virus derived from infections of mouse cells with single heteroduplexes have been analyzed to determine how the genotypic markers of the parental heteroduplex segregate. Markers that are separated by a length of DNA greater than 600 nucleotides segregate independently. Segregation was not detected between two markers separated by only approximately 90 nucleotides. We interpret these results on the basis of the correction of mismatched base-pair regions in the heteroduplex before the completion of DNA replication. We suggest that this technique provides valuable information concerning gene conversion in mamalian cells and permits the transfer of genotypic markers from one virus strain to another.