[Correlation of antigenic properties of influenza viruses of the H3N2 subtype with changes in the amino acid sequence of hemagglutinins].

The effect of amino acid substitutions within the antigenic sites, the residues close to these sites, and the other parts of the hemagglutinin molecule on cross-reactions between influenza subtype H3N2 virus strains in hemagglutination-inhibition tests are considered. Previously we reported a method for calculation of the values of immunochemical cross-reactions between the homologous proteins based on the structural data. On this basis, a method for calculation of the titers of cross-reactions of influenza viruses in hemagglutination-inhibition tests is proposed. The values obtained by this method show a good correlation with the known experimental data. Analysis of the nature of amino acid replacements in region D located in the interface between the hemagglutinin subunits has shown that this region cannot bind with antibodies. The data on the limitation of the resource of the subtype H3N2 variability are presented.