Genetic variability of epidemic strains of influenza virus serotypes H1N1 and H3N2 during antigenic drift

Data are presented on structural variability of individual genes of selected variants of epidemic influenza viruses H1N1 (1977-1979) and H3N2 (1968-1979) in the course of antigenic drift obtained by oligonucleotide mapping. Six out of 8 genes of H1N1 viruses were found to be more variable than the corresponding genes of H3N2 viruses. Only HA and NS genes of H3N2 viruses underwent greater structural changes as compared with the analogous genes of H1N1 viruses. In viruses of both serotypes, most variable were the genes coding for hemagglutinin and matrix protein. Possible causes of greater structural variability of the matrix protein gene in the course of antigenic drift are discussed.     

Antigenic determinants in influenza virus hemagglutinin.

Three antigenic determinants were revealed in H3 hemagglutinin of influenza A viruses isolated from 1968 to 1975. One of them was common for all viruses, and two others specified differences between the viruses possessing H3 hemagglutinin.     

The primary structure of the hemagglutinin of influenza A (H3N2) viruses isolated in the USSR in 1985

The primary structure of hemagglutinin of the members of three main antigenic groups of current influenza A (H3N2) viruses was determined. A phenomenon of "antigenic mimicry" was found to be due to the accumulation of reversions in hemagglutinin structure at late stages of antigenic drift.