Epidemiology and Infection



Characterization of H9N2 influenza A viruses isolated from chicken products imported into Japan from China


M. MASE a1c1, M. ETO a2, K. IMAI a3, K. TSUKAMOTO a1 and S. YAMAGUCHI a1
a1 Department of Infectious Diseases, National Institute of Animal Health, Kannondai, Tsukuba, Ibaraki, Japan
a2 Animal Quarantine Service, Haramachi, Yokohama, Japan
a3 Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro, Hokkaido, Japan

Article author query
mase m   [PubMed][Google Scholar] 
eto m   [PubMed][Google Scholar] 
imai k   [PubMed][Google Scholar] 
tsukamoto k   [PubMed][Google Scholar] 
yamaguchi s   [PubMed][Google Scholar] 

Abstract

We characterized eleven H9N2 influenza A viruses isolated from chicken products imported from China. Genetically they were classified into six distinct genotypes, including five already known genotypes and one novel genotype. This suggested that such multiple genotypes of the H9N2 virus have possibly already become widespread and endemic in China. Two isolates have amino-acid substitutions that confer resistance to amantadine in the M2 region, and this supported the evidence that this mutation might be a result of the wide application of amantadine for avian influenza treatment in China. These findings emphasize the importance of surveillance for avian influenza virus in this region, and of quarantining imported chicken products as potential sources for the introduction of influenza virus.

(Accepted April 10 2006)
(Published Online July 7 2006)


Correspondence:
c1 Department of Infectious Diseases, National Institute of Animal Health, 3-1-5 Kannondai, Tsukuba, Ibaraki 305-0856, Japan. (Email: masema@affrc.go.jp)


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