[New sites in the hemagglutinin composition of epidemic variants of the influenza virus A (H3N2) from 1989-1990].
Immunological analysis of the antigenic structure of hemagglutinin of newly isolated variants of influenza (H3N2) virus carried out using monoclonal and monospecific antibodies to individual antigenic sites of hemagglutinin showed the 1989-1990 isolates to be markedly different in their antigenic properties from the variants isolated in previous years. Sites with new antigenic properties were determined in hemagglutinin of the isolates. Wide variability was found in the region of three immunodominant sites. The fact of circulation in the human population of influenza viruses of one subtype with different antigenic structures within the limits of one epidemic season was established.