Genome analysis of H1N1 influenza virus strains isolated in the U.S.S.R. during an epidemic in 1961-1962.

Genome composition and polypeptides of H1N1 influenza virus strains isolated in the U.S.S.R. during an epidemic in 1961-1962 have been studied as well as H2N2 influenza virus strains that dominated at that time. The H1N1 isolates did not contain genes of the simultaneously circulating H2N2 viruses. H1N1 influenza viruses have proved to be genetically similar to A/FM/1/47 (H1N1) influenza virus strain differing in only two genes, rather than to H1N1 influenza viruses isolated in 1977 differing in six genes.