[Persistence of the genes of epidemic influenza viruses (H1N1) in natural populations].

A comparative study of antigenic determinants and genome of the analogues of epidemic H1N1 variants isolated from various animal species and from man in the USSR and Mongolia in 1978--1980 was carried out. The analysis of the antigenic determinants of hemagglutinins of the viruses isolated in this period from man, domestic and wild birds and animals performed with a set of monoclonal antibodies to the epidemic reference A/Brazil/11/78 virus revealed their close similarity in the structure of the antigenic sites. Study of neuraminidase of these viruses with a set of monoclonal antibodies to the A/Denver/1/57 strain showed their relationship with neuraminidase of the viruses isolated in 1957 and revealed its trend for changes in individual antigenic determinants. The analysis of genomes of the viruses isolated in Mongolia from man and animals by the methods of RNA polyacrylamide gel electrophoresis and RNA--RNA hybridization showed them to be close to each other and to differ from the epidemic A/USSR/90/77 strain. At the same time, the Mongolian isolates showed differences in the electrophoretic mobility of the genome fragments coding for hemagglutinin and neuraminidase synthesis.