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BioMed Research International
Volume 2015, Article ID 267520, 6 pages
Research Article

Phylogenetic Analysis of Hemagglutinin Genes of H9N2 Avian Influenza Viruses Isolated from Chickens in Shandong, China, between 1998 and 2013

1College of Life Sciences, Taishan Medical University, Tai’an 271000, China
2College of Basic Medicine, Taishan Medical University, Tai’an 271000, China
3College of Animal Science and Technology, Shanxi Agricultural University, Taigu 030800, China
4Animal Disease Control Center, Animal Husbandry Bureau of Daiyue, Tai’an 271000, China

Received 22 June 2015; Accepted 31 August 2015

Academic Editor: Gregory Tannock

Copyright © 2015 Yuxin Zhao et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Since H9N2 avian influenza virus (AIV) was first isolated in Guangdong province of China, the virus has been circulating in chicken flocks in mainland China. However, a systematic phylogenetic analysis of H9N2 AIV from chickens in Shandong of China has not been conducted. Based on hemagglutinin (HA) gene sequences of H9N2 AIVs isolated from chickens in Shandong of China between 1998 and 2013, genetic evolution of 35 HA gene sequences was systematically analyzed in this study. Our findings showed that the majority of H9N2 AIVs (21 out of 35) belonged to the lineage h9.4.2.5. Most of isolates (33 out of 35) had a PSRSSR↓GLF motif in HA cleavage site. Importantly, 29 out of these 35 isolates had an amino acid exchange (Q226L) in the receptor-binding site. The substitution showed that H9N2 AIVs had the potential affinity to bind to human-like receptor. The currently prevalent H9N2 AIVs in Shandong belonged to the lineage h9.4.2.5 which are different from the vaccine strain SS/94 clade h9.4.2.3. Therefore, the long-term surveillance of H9N2 AIVs is of significance to combat the possible H9N2 AIV outbreaks.