[The mapping of the hemagglutinin sites of the influenza viruses H3N2 isolated in 1990-1993].

: The antigenic structure of hemagglutinin (HA) of influenza A (H3N2) viruses was found to have undergone significant changes which markedly distinguished the new isolates of previously occurring strains. Investigations of the epidemic variants using monospecific and monoclonal antibodies revealed strains with original HA sites previously unfound in H3N2 viruses. The emergence of the sites with the new properties determined the epidemic activity of the viruses isolated in this period.