An outbreak of avian influenza subtype H9N8 among chickens in South Korea.
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.
Kwon
Yong Kuk
YK
National Veterinary Research and Quarantine Service, MAF, Anyang 430-824, Korea.
Lee
Youn Jeong
YJ
Choi
Jun Gu
JG
Lee
Eun Kyoung
EK
Jeon
Woo Jin
WJ
Jeong
Ok Mi
OM
Kim
Min Chul
MC
Joh
Seong Joon
SJ
Kwon
Jun Hun
JH
Kim
Jae Hong
JH
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*