P1 and P3 proteins of influenza virus are required for complementary RNA synthesis.

Members of two temperature-sensitive (ts) mutant groups of influenza A/WSN virus defective in complementary RNA synthesis were analyzed with respect to the identity of their defective genes. RNA analysis of recombinants having a ts+ phenotype derived from the mutants and HK virus permitted the identification of RNA 1 and RNA 2 as the single defective gene in mutant groups I and III, respectively. Based on knowledge obtained by mapping the WSN virus genome, it then was possible to determine that biologically functional P3 protein (coded for by RNA 1) and P1 protein (RNA 2) are required for complementary RNA synthesis of influenza virus.