title: An outbreak of avian influenza subtype H9N8 among chickens in South Korea.
abstract: Low pathogenic avian influenza subtype H9N8 was diagnosed on a Korean native chicken farm in Gyeonggi province, South Korea, in late April 2004. Clinical signs included moderate respiratory distress, depression, mild diarrhoea, loss of appetite and a slightly elevated mortality (1.4% in 5 days). Pathologically, mucopurulent tracheitis and air sacculitis were prominently found with urate renal deposition. The isolated A/chicken/Kr/164/04 (H9N8) had an Ala-Ser-Gly-Arg (A/S/G/R) motif at the cleavage site of haemagglutinin, which has been commonly found in H9N2 isolated from Korean poultry. Phylogenetic analysis of the haemagglutinin and neuraminidase genes of the H9N8 avian influenza virus (AIV) isolate showed that reassortment had occurred. Its haemagglutinin gene was similar to that of Korean H9N2 AIVs, but its neuraminidase gene was closely related to that of A/WBF/Kr/KCA16/03 (H3N8) isolated from the faeces of wild birds in Korea. The pathogenicity of the isolate was tested on 6-week-old specific pathogen free chickens. The inoculated virus (H9N8) was recovered from most tested organs, including the trachea, lung, kidney, spleen, and caecal tonsil. This is the first report of an outbreak of low pathogenic avian influenza in chickens caused by AIV subtype H9N8.
authors.affiliation: National Veterinary Research and Quarantine Service, MAF, Anyang 430-824, Korea.
authors.forename: Yong Kuk
authors.initials: YK
authors.lastname: Kwon
authors.forename: Youn Jeong
authors.initials: YJ
authors.lastname: Lee
authors.forename: Jun Gu
authors.initials: JG
authors.lastname: Choi
authors.forename: Eun Kyoung
authors.initials: EK
authors.lastname: Lee
authors.forename: Woo Jin
authors.initials: WJ
authors.lastname: Jeon
authors.forename: Ok Mi
authors.initials: OM
authors.lastname: Jeong
authors.forename: Min Chul
authors.initials: MC
authors.lastname: Kim
authors.forename: Seong Joon
authors.initials: SJ
authors.lastname: Joh
authors.forename: Jun Hun
authors.initials: JH
authors.lastname: Kwon
authors.forename: Jae Hong
authors.initials: JH
authors.lastname: Kim
mesh_terms: D000818:Animals; D002645:Chickens; D004196:Disease Outbreaks / Q000662:veterinary*; D009980:Influenza A virus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D005585:Influenza in Birds / Q000453:epidemiology* / Q000821:virology*; D007723:Korea / Q000453:epidemiology; D010802:Phylogeny; D011201:Poultry Diseases / Q000453:epidemiology* / Q000821:virology*