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

Yuxin Zhao,Quanhai Pang,Yujing Tang,Yufa Zhou,Song Li,Wengang Song,Zengmin Miao

doi:10.1155/2015/267520

Abstract

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.

Highlights

Since H9N2 subtype avian influenza virus (AIV) was first isolated in Guangdong province of China in 1994, this subtype influenza virus has quickly spread to other areas of China and become prevalent in poultry [1,2,3]
A total of 35 HA gene sequences of H9N2 AIVs isolated from chickens in Shandong of China between 1998 and 2013 were obtained from the National Center for Biotechnology Information (NCBI) Influenza Viruses Resource (Table 1)
HA gene nucleotide sequences and deduced amino acid (AA) sequence identities among the 35 tested strains ranged from 84.0 to 100.0% and 89.1 to 100.0%, respectively

Summary

Introduction

Since H9N2 subtype avian influenza virus (AIV) was first isolated in Guangdong province of China in 1994, this subtype influenza virus has quickly spread to other areas of China and become prevalent in poultry [1,2,3]. It is noteworthy that the number of humans infected by H9N2 AIV in serological surveillance, especially poultry workers, was much higher than that of the confirmed cases [12, 13]. H9N2 AIV is able to reassort with other subtypes of influenza virus, including H6N1, H6N2, H5N1, and H7N9. The increased risk of animalto-human spread with avian viruses that have the H9N2 internal genes has posed a greater pandemic threat [14,15,16]

Methods

Results

Conclusion