[Activity of virion RNA-polymerase in influenza A and B virus variants with different pathogenicities for mice].

RNA polymerase activities in parental strains of influenza A and B viruses nonpathogenic for mice and their pathogenic variants have been studied. The parental strains are A/seal/Massachusetts 1/80, A/USSR 05/81, A/Philippines 2/82, B/Singapore 222/79. The RNA polymerase activity has been also studied in recombinant strains obtained by crossing various parental strains, one of which is pathogenic for mice (AR/PR 8/34), and having different degrees of pathogenicity. The nonpathogenic viruses had low transcriptase activity. RNA polymerase activity in pathogenic variants is shown to be 1.5-3 times higher than that in the parental strains. All the recombinants, whatever their pathogenicity, had approximately the same transcriptase activities which were 1.5-2 times higher than those registered in parental nonpathogenic strains.