Antigenic variation in current human type A influenza viruses: antigenic characteristics of the variants and their geographic distribution.
Outbreaks of influenza due to the virus A/Hong Kong/1/68 (H3N2) began in 1968 and are still occurring. The haemagglutinin of this virus is different from that of the A/Singapore/1/57 virus (the "Asian" strain) but the neuraminidase antigens are the same. Between 1968 and 1971 only minor antigenic "drift" in the haemagglutinin was noted, but in recent months 2 isolates have been identified in which considerable "drift" has occurred in the haemagglutinin and in the neuraminidase antigens. One, A/Hong Kong/5/72 (H3N2), was first detected in outbreaks in Hong Kong between November 1971 and January 1972 and was predominant there and in Korea but did not become widely disseminated. The second strain, A/England/42/72 (H3N2), has been isolated in winter outbreaks in the southern hemisphere and now appears to be the predominant strain in the northern hemisphere. The characteristics of the strains are described.
D000349:Africa; D000956:Antigens, Viral; D001208:Asia; D001315:Australia; D005060:Europe; D005827:Genetics, Microbial; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D005779:Immunodiffusion; D007125:Immunogenetics; D007251:Influenza, Human / Q000453:epidemiology; D009439:Neuraminidase / Q000037:antagonists & inhibitors; D009656:North America; D009975:Orthomyxoviridae / Q000276:immunology*; D013020:South America
D000956:Antigens, Viral; D009439:Neuraminidase