Isolation and characterization of influenza A viruses from wild ducks in northern Japan: appearance of HSW1 antigens in the Japanese duck population.
Twenty-six influenza A viruses were isolated from cloacal and tracheal samples of 235 resident and 396 migratory ducks in Miyagi prefecture, Japan, in 1977--78. Of these, twelve were antigenically related to the avian-origin HSW1 virus, A/duck/Alberta/35/76 (HSW1N1), but their neuraminidase antigens were characterized as Nav2-3, Nav4 or N2. These antigenic configuration have not previously been reported. In addition, one strain in which the neuraminidase antigen was identified as Nav4, was demonstrated to be a mixture of two haemagglutinins, HSW1 and Hav7. Two distinct strains were separated from the mixture and characterized as HSW1Nav4 and Hav7Nav4. The antigenic identification of an additional 13 influenza A viruses revealed the presence of six haemagglutinin subtypes (Hav1, Hav3, Hav4, Hav6, Hav7, and Hav8) and five neuaraminidase subtypes (Nav1, Nav2-3, Nav4, Neq2, and N2) in various combinations. The results suggest that the avian influenza A viruses among feral ducks may be isolated in various combinations of haemagglutinins and neuraminidase subtypes in Japan, and that feral ducks may be the site of genetic recombination occurring as a result of dual infection with different subtypes of influenza A virus.
D000818:Animals; D000956:Antigens, Viral / Q000145:classification*; D002988:Cloaca / Q000382:microbiology; D004372:Ducks / Q000382:microbiology*; D006389:Hemagglutinins, Viral / Q000145:classification; D009980:Influenza A virus / Q000276:immunology* / Q000302:isolation & purification*; D007564:Japan; D009439:Neuraminidase / Q000276:immunology; D014132:Trachea / Q000382:microbiology
D000956:Antigens, Viral; D006389:Hemagglutinins, Viral; D009439:Neuraminidase