Temperature-sensitive mutants of influenza A/Udorn/72 (H3N2) virus II. Genetic analysis and demonstration of intrasegmental complementation

Abstract

Temperature-sensitive ( ts) mutants of influenza A/Udorn/72 (H3N2) virus were classified into complementation and recombination groups. Eighty-three ts mutants formed 13 complementation groups, but only 8 recombination groups. Four recombination groups contained viruses representing more than one complementation group; recombination groups B, C, and F each had two complementing members and group H had four. The locus of the ts mutation(s) in each of the complementing members of the 4 recombination groups was analyzed by segregation analysis. Both complementing members of recombination group C had a ts mutation on the P2 gene. This indicated that intrasegmental complementation occurred between these two ts mutants. Similarly, intrasegmental complementation occurred between viruses processing a ts mutation on the NS gene. Suggestive evidence for intrasegmental complementation between ts mutants possessing a ts mutation in the NP or P1 gene was obtained. These observations considered together with other published studies indicate that mutations permitting intrasegmental complementation can occur in the majority of the influenza A virus genes, i.e., P3, P1, P2, NA, NP, and NS. The investigation of complementing mutants in these genes should prove helpful in elucidating multiple functions of influenza A virus gene products.