J Vet Sci.  2015 Sep;16(3):317-324. 10.4142/jvs.2015.16.3.317.

Isolation and phylogenetic analysis of hemagglutinin gene of H9N2 influenza viruses from chickens in South China from 2012 to 2013

  • 1College of Animal Science, South China Agricultural University, Guangzhou 510642, China. fengch@scau.edu.cn
  • 2Guangdong Wen's Foodstuff Group Co. Ltd., Guangdong Enterprise Key Laboratory for Animal Health and Environmental Control, Yunfu 527439, China.


As part of our ongoing influenza surveillance program in South China, 19 field strains of H9N2 subtype avian influenza viruses (AIVs) were isolated from dead or diseased chicken flocks in Guangdong province, South China, between 2012 and 2013. Hemagglutinin (HA) genes of these strains were sequenced and analyzed and phylogenic analysis showed that 12 of the 19 isolates belonged to the lineage h9.4.2.5, while the other seven belonged to h9.4.2.6. Specifically, we found that all of the viruses isolated in 2013 belonged to lineage h9.4.2.5. The lineage h9.4.2.5 viruses contained a PSRSSRdownward arrowGLF motif at HA cleavage site, while the lineage h9.4.2.6 viruses contained a PARSSRdownward arrowGLF at the same position. Most of the isolates in lineage h9.4.2.5 lost one potential glycosylation site at residues 200-202, and had an additional one at residues 295-297 in HA1. Notably, 19 isolates had an amino acid exchange (Q226L) in the receptor binding site, which indicated that the viruses had potential affinity of binding to human like receptor. The present study shows the importance of continuing surveillance of new H9N2 strains to better prepare for the next epidemic or pandemic outbreak of H9N2 AIV infections in chicken flocks.


H9N2 subtype; avian influenza virus; phylogenetic analysis; South China

MeSH Terms

Hemagglutinin Glycoproteins, Influenza Virus/chemistry/*genetics/metabolism
Influenza A Virus, H9N2 Subtype/*genetics/metabolism
Influenza in Birds/virology
Poultry Diseases/*virology
Sequence Analysis, RNA/veterinary
Hemagglutinin Glycoproteins, Influenza Virus
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