| pubmed-article:483778 | pubmed:abstractText | Drift variants of influenza viruses of the groups Hsw1, H0 and H1 including the A/USSR/77 (H1N1) virus. Major subunits of Hsw1, H0, and H1 hemagglutinins having common oligopeptides differ considerably in other oligopeptides. Within the H1 antigen viruses there are differences between the viruses of the early (1947), middle (1950--1952), and late (1956) periods of circulation. The latter (1956) differ markedly from their predessessors. The A/USSR/77 virus is most close to A/Fort Warren/50 virus. Oligopeptide maps of minor hemagglutinin subunits of all the viruses under study differ little from each other. Some suggestions on the causes of the great variability of the HA1 chain and conservatism of the HA2 hemagglutinin chain are given. | lld:pubmed |
