Characterization of a human H9N2 influenza virus isolated in Hong Kong.
Two H9N2 viruses were isolated, for the first time, from humans in Hong Kong in 1999. Isolation of influenza viruses with a novel subtype of the hemagglutinin (HA) drew attention of health care authorities worldwide from the view of pandemic preparedness. Sequence analysis of the HA genes reveals that HA of A/Hong Kong/1073/99 (H9N2) is most closely related to that of A/quail/HK/G1/97 (H9N2) that contains the internal genes similar to those of Hong Kong/97 (H5N1) viruses. Phylogenetic and antigenic analyses demonstrated the diversity among H9 HA. A/Hong Kong/1073/99 was shown to cause a respiratory infection in Syrian hamsters, suggesting that the virus can replicate efficiently in mammalian hosts. We developed a whole virion test vaccine with a formalin-inactivated egg-grown HK1073. Intraperitoneal administration of the vaccine twice to hamsters conferred a complete protection against challenge infection by the MDCK cell-grown homologous virus. Receptor specificity of HK1073 appeared different from that of other avian influenza viruses of H9 subtype which recognize preferentially alpha-2,3 linked sialic acid. Hemagglutination of HK1073 with guinea pig erythrocytes was inhibited by both alpha-2,3 and alpha-2,6 linked sialic acid containing polymers. These data suggested that HK1073 had acquired a broader host range, including humans. Together with data so far available, the present study suggested that isolation of the H9 influenza viruses from humans requires precaution against the emergence of a novel human influenza.
Saito
T
T
Department of Virology I, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo, Japan. taksaito@nih.go.jp
Lim
W
W
Suzuki
T
T
Suzuki
Y
Y
Kida
H
H
Nishimura
S I
SI
Tashiro
M
M
D000818:Animals; D000956:Antigens, Viral / Q000276:immunology; D001208:Asia; D002417:Cattle; D002478:Cells, Cultured; D002642:Chick Embryo; D002648:Child; D006224:Cricetinae; D004285:Dogs; D005060:Europe; D005260:Female; D006001:Glycoconjugates / Q000494:pharmacology; D006168:Guinea Pigs; D006386:Hemagglutination Tests; D006387:Hemagglutination, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics / Q000502:physiology; D006723:Hong Kong; D006736:Horses; D006801:Humans; D053127:Influenza A Virus, H9N2 Subtype; D009980:Influenza A virus / Q000145:classification / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification* / Q000502:physiology; D007252:Influenza Vaccines / Q000276:immunology; D007251:Influenza, Human / Q000517:prevention & control / Q000662:veterinary / Q000821:virology*; D008168:Lung / Q000821:virology; D008297:Male; D008647:Mesocricetus; D019158:N-Acetylneuraminic Acid / Q000378:metabolism; D009656:North America; D010802:Phylogeny; D011200:Poultry / Q000821:virology; D011201:Poultry Diseases / Q000821:virology; D011991:Receptors, Virus / Q000378:metabolism; D012756:Sheep; D013045:Species Specificity; D013552:Swine; D013553:Swine Diseases / Q000821:virology; D014611:Vaccination; D015164:Vaccines, Inactivated; D014771:Virion / Q000276:immunology; D014776:Virus Cultivation
D000956:Antigens, Viral; D006001:Glycoconjugates; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007252:Influenza Vaccines; D011991:Receptors, Virus; D015164:Vaccines, Inactivated; D019158:N-Acetylneuraminic Acid