Extragenic suppression of temperature-sensitive mutations in RNA segment 8 by replacement of different RNA segments with those of other influenza A virus prototype strains

Extragenic suppression by replacement of different RNA segments has been detected during rescue by other prototype influenza strains of temperature-sensitive ( ts) mutants of an influenza virus with lesions in segment 8. The ts + recombinants obtained in this way usually had not replaced the RNA segment (= gene) with the is lesion, but they had replaced other RNA segments depending on the strain used for rescue. Backcross experiments with the parental strain showed that the is lesion was extragenically suppressed by introducing a foreign RNA segment. The results are discussed in terms of a cooperation between one of the gene products of RNA segment 8 (nonstructural proteins) and the RNA polymerase complex.