[Characteristics of the biological and antigenic properties of reference strains of the influenza B virus at various periods of isolation].

The results of a comparative analysis of biological and antigenic properties of reference influenza B virus strains, B/Lee/40, B/Singapore/222/79, and B/USSR/100/83, are presented. The most marked changes were found in the antigenic properties of hemagglutinin and neuraminidase. Hemagglutinins of the strains under study were found to have both common antigens and qualitatively different strain-specific determinants. The degree of intensity of immunity to the challenge B/Singapore/222/79 Pm+ virus corresponded to the intensity of antigenic relationship in the strains under study.