Genetic recombination between temperature-sensitive and wild-type influenza A virus strains.

Genetic cross was performed between a temperature-sensitive (ts) mutant of influenza virus A/WSN (H0N1) which carries a ts lesion in M gene, and a wild type A/Aichi/2/68 (H3N2). Twelve clones were isolated randomly from the mixed yield in the absence of any selective procedure and they were individually examined for their ts character. In addition, structural and non-structural polypeptides of an individual clone were analyzed by SDS-polyacrylamide gel electrophoresis (PAGE) to identify from which parent each viral protein was derived. The experiments have shown that at high frequency recombination occurred with respect to every major viral protein; this is compatible with the view that recombination with influenza viruses is actually a mere exchange of RNA segments.