Isolation of influenza A viruses with a new antigenic formula from wild birds.

: Three hemagglutinating agents were isolated from mixed pools of the viscera from black-headed gulls (Larus ridibundus) and robin (Erithacus rubecula) collected in the Byelorussian SSA and the Kaliningrad region of the RSFSR. Typing of the viruses by double immunodiffusion technique revealed antigenic relationships of the viruses with swine hemagglutinin (Hsw1) and human hemagglutinin H0. One of the strains had neuraminidase N2 the other two Nav2. An analysis of the polypeptide composition of the virus showed the molecular weights of the heavy (HA1) and light (HA2) hemagglutinin chains to be similar in both strains (about 50,000 and 25,000 daltons, respectively). The strains had a low content of the light hemagglutinin chain (HA2) which is typical for viruses having Hsw1 hemagglutinin.