Gene composition of high-yielding influenza vaccine strains obtained by recombination.

The genetic composition of 11 high-yielding recombinants of influenza virus was determined by polyacrylamide gel electrophoresis of the 32P-labeled RNAs obtained from the recombinants and their parental viruses. The high-yield recombinants that were selected for potential use as vaccine strains contained the surface hemagglutinin and neuraminidase antigens of the low-yielding parental viruses. The increased growth capacity of the recombinants is associated with the presence of genes derived from the high-yielding laboratory strain A/Puerto Rico/8/34. Although increased growth capacity in these recombinants could not be attributed to specific genes or gene combinations, all of the high-yielding recombinants examined derived the M gene from the A/Puerto Rico/8/34 parent.