[Changes in the antigenic composition of virus A (H1N1) hemagglutinin in 1977-1982 detected by using monoclonal antibodies].

Parallel studies of influenza A (H1N1) strains by the micro-HI method using monoclonal antibodies, antivirion sera obtained by immunization of rats, and by the immunoadsorption of rats, and by the immunoadsorption test showed monoclonal antibodies to detect the antigenic drift most definitely. Among 156 strains isolated in 1977-1982 in various parts of the USSR and abroad, 6 antigenic drift variants were detected differing in the content and combination of epitopes recognized by different monoclonal antibodies to the A/USSR/90/77 strain. Three of them have first been found. The quantitative decrease in an epitope activity was established to precede its disappearance and may be used as a prognostic sign. Among 5 epitopes tested, most labile were those recognized by monoclones Nos. 264, 110, and 18. They began to disappear since 1978-1979. The epitopes recognized by monoclones Nos. 70 and 22 were most conservative and were still found in the strains isolated in 1982.