TS-MUTATIONS IN GENOMES OF THE INFLUENZA- A HONG-KONG/1/68 (H3N2) ANDINFLUENZA-A/VICTORIA/35/72 (H3N2) COLD-ADAPTED VIRUSES/

The phenotype and localization of ts mutations in genomes of the influ enza A/Victoria/30-ir (A/Vic/30-ir) and A/Hong Kong/17-ir (A/HK/17-ir) cold-adapted (ca) viruses were studied. Using the recombination analy sis in chick embryo fibroblasts (CEF) we determined that influenza A/H K/17-ir ca virus carries ts mutations in three <<internal genes>> i.e. , PB1, NP and M, and influenza A/Vic/30-ir ca virus carries ones in fo ur genes, i.e., PA, NP, M and NS. We have revealed ts mutations for NA gene in none of these, viruses. Prior to the analysis of ts mutations in HA gene of influenza A/HK/17-ir and A/Vic/30-ir ca viruses, three cloning steps were performed in chick embryos (CE) by the method of li miting dilutions at 34-degrees-C followed by selection of some strains with the most prominent ts phenotype. The cloned strains with such ph enotypes were shown to repeat stable results within the recombination analysis in CE, i.e., none from the cloned strains of A/HK/17-ir ca vi rus recombined in CE at 40-degrees-C with the 46 ts mutant, while reco mbination of this mutant with the cloned A/Vic/30-ir ca strains led to formation of the ts progeny. Thereafter our data result in conclusion that ts mutations in the PA gene must lead to some insignificant cont ribution for the expression of general ts phenotype among the ca strai ns as far as this sign is clearly displayed by both viruses, although only one of them, i.e., A/HK/17-ir carries ts mutation in the HA gene.