Genome analysis of influenza A virus strains isolated during an epidemic of 1979-1980.

The genome and polypeptides of influenza A virus H3N2 strains isolated during the epidemic of 1979-1980 in the U.S.S.R. and G.D.R. have been analysed. Five varieties of H3N2 strains differing in a number of genes have been found. The isolates of the first group was similar to the A/Texas/1/77 strain in all the genes; the isolates of the second group were similar to the A/Bangkok/1/79 strain in all the genes; the strain representative of the third variety, contained all the genes except gene 4 close to those of the A/Bangkok/1/79 strain; the isolates of the fourth group contained genes 7 and 8 similar to those of the A/Bangkok/1/79 strain while the other genes corresponded to those of no strains under comparison; the viruses of the fifth group contained gene 3 similar to that of A/Moscow/406/76 strain, gene 7 was similar to that of A/Texas/1/77 strain and the other genes differed from all other strains compared. The data obtained indicate that during an influenza epidemic occurring in certain region several influenza virus varieties of the same serotype can circulate simultaneously, differing not only in the antigenic specificity of the haemagglutinin, but also in other genes.