| Abstract: | Immunological analysis of antigenic determinants in the composition of hemagglutinins (HA) of H1N1 viruses isolated in the epidemic season of 1978-1979 showed their difference from A/USSR/090/77 virus HA. The A/Brazil/11/78 HA is characterized by 3 antigenic determinants two of which are identical with those of A/USSR/090/77 HA and one shows relationship with HA determinant of A/Omachi/1/53 virus, A/Fukushima/103/78 and A/Kagoshima/22/79 HAs are characterized by 1 determinant common with that of A/USSR/090/77 HA and 2 determinants identical with A/Omachi/1/53 virus HA. HAs of these viruses contain a determinant responsible for the antigenic relation of A/Omahi/1/53 HA with that of H1N1 viruses isolated in 1956-1957. The results suggest that the antigenic drift of HA of H1N1 viruses isolated in 1977-1979 occurs by the cycle characteristic of HA of H1N1 viruses isolated in 1950-1957. By the sensitivity to alpha-, beta-, and gamma-inhibitory of rabbit serum H1N1 viruses isolated in 1947-1957 and in 1977-1979 are quite similar with the exception of A/USSR/184/79 virus showing high sensitivity to gamma-inhibitors like H2N2 and H2N2 viruses. |
