ANALYSIS OF GENE RECOMBINATION ACTIVITY O F ANIMAL INFLUENZA-VIRUS HEMAGGLUTININ GENES IN THE PROCESS OF THEIR ADAPTATION TO A NEW HOST, MAN

The authors tried to decode the mechanism of influenza viruses species adaptation in the process of host changing. The functionally importan t replacement in the surface pocket domains were revealed, particularl y in the conservative region 221-241, involving fibronectin-like part. Close replacements were revealed in the region 141-161. The method of construction of heteroduplexes between hemagglutinin RNA of duck, pig , and human viruses was used. The method showed that all heteroduplexe s formed recombinogene structures. An unexpected effect of directional recombination was elicited for hemagglutinin RNA heteroduplexes in ca ses of duck-pig and human-pig viruses. During the directional recombin ation the following processes took place: the receptor-binding site of animal type was transmitted to the duck virus, while the human recept or-binding site was transmitted to the pig virus. According to the exp erimental data, a new hypothesis is formulated: the cascade mechanism of directional recombination for duck, animal and human viruses makes it' possible for the recombinant viruses to overcome interspecies barr iers.