Abstract: | Ninety-eight hemagglutinating agents were isolated from washings of cloaca and organs of 750 birds collected in southern and southeastern regions of the Kazakh SSR. Determinations of their type appurtenance allowed 36 agents to be classified into influenza A virus. Among them 4 strains had H1N1 surface antigens, 29 strains were Hav2 Nav5 and 3 strains had unidentified neuraminidase and Hav2. The data on the biological properties of influenza virus strains of both subtypes are presented. |