Comparative study of influenza virus H2 (Asian) hemagglutinins isolated from human and avian sources

The hemagglutinin of an influenza virus isolated from a wild duck (Pintail, Anas acuta) in the USSR in 1976 had been found to be antigenically indistinguishable from the hemagglutinin of H2N2 viruses of human origin isolated in 1957. The hemagglutinins from viral preparations of the A/Anas acuta/Primorie/695/76 (H2Nav2) and A/Singapore/1/57 (H2N2) strains were purified by SDS gel chromatography as the subunits HA1 and HA2. Comparison of amino acid compositions and peptide maps of tryptic peptides containing [14C]-carboxymethylcysteine showed a striking degree of similarity between the H2 hemagglutinins.