[Detection of a heterogeneous population of influenza virus type A/H1N1 with monoreceptor sera to hemagglutinin antigenic determinants].

Studies of the antigenic composition of hemagglutinins of influenza H1N1 virus variants isolated in 1981 using monoreceptor antibody to individual antigenic determinants obtained by the selective adsorption method showed some variants to represent heterogeneous populations manifesting antigenic properties of different H1N1 viruses. Passages of the heterogeneous virus in the presence of antiinfluenza serum resulted in cloning a subpopulation with the antigenic properties of the hemagglutinin similar to that of H1N1 viruses which had circulated in the end of the first period of epidemic activity of H1N1 viruses. The method "from-plaque-to-plaque" passages in MDCK cells yielded from the heterogeneous population a homogeneous variant which by the hemagglutinin antigenic properties was similar to H1N1 viruses isolated in 1956-1957.