title: Characterization of avian influenza viruses isolated from domestic ducks in Vietnam in 2009 and 2010.
abstract: In the surveillance of avian influenza in Vietnam, 26 H9N2, 1 H3N2, 1 H3N8, 7 H4N6, 3 H11N3, and 1 H11N9 viruses were isolated from tracheal and cloacal swab samples of 300 domestic ducks in April 2009, and 1 H9N6 virus from 300 bird samples in March 2010. Out of the 27 H9 virus isolates, the hemagglutinins of 18 strains were genetically classified as belonging to the sublineage G1, and the other nine belonged to the Korean sublineage. Phylogenetic analysis revealed that one of the 27 H9 viruses was a reassortant in which the PB2 gene belonged to the Korean sublineage and the other seven genes belonged to the G1 sublineage. Three representative H9N2 viruses were intranasally inoculated into ducks, chickens, pigs, and mice. On the basis of experimental infection studies, it was found that each of the three viruses readily infected pigs and replicated in their upper respiratory tracts, and they infected chickens with slight replication. Viruses were recovered from the lungs of mice inoculated with two of the three isolates. The present results reveal that H9 avian influenza viruses are prevailing and genetic reassortment occurs among domestic ducks in Vietnam. It is recommended that careful surveillance of swine influenza with H9 viruses should be performed to prepare for pandemic influenza.
authors: Laboratory of Microbiology, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Kita 18 Nishi 9, Kita-ku, Sapporo 060-0818, Japan.
authors: Naoki
authors: N
authors: Nomura
authors: Yoshihiro
authors: Y
authors: Sakoda
authors: Mayumi
authors: M
authors: Endo
authors: Hiromi
authors: H
authors: Yoshida
authors: Naoki
authors: N
authors: Yamamoto
authors: Masatoshi
authors: M
authors: Okamatsu
authors: Kenji
authors: K
authors: Sakurai
authors: Nam Van
authors: NV
authors: Hoang
authors: Long Van
authors: LV
authors: Nguyen
authors: Huy Duc
authors: HD
authors: Chu
authors: Tien Ngoc
authors: TN
authors: Tien
authors: Hiroshi
authors: H
authors: Kida
mesh_terms: D000818:Animals; D000829:Animals, Domestic / Q000821:virology; D002645:Chickens; D004372:Ducks / Q000821:virology*; D005260:Female; D006801:Humans; D053127:Influenza A Virus, H9N2 Subtype / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity; D009980:Influenza A virus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity; D005585:Influenza in Birds / Q000821:virology*; D007251:Influenza, Human / Q000821:virology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009976:Orthomyxoviridae Infections / Q000821:virology; D010802:Phylogeny; D011201:Poultry Diseases / Q000821:virology; D016865:Reassortant Viruses / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity; D013552:Swine; D013553:Swine Diseases / Q000821:virology; D014744:Vietnam; D014774:Virulence