Phylogenetic classification of hemagglutinin gene of H9N2 avian influenza viruses isolated in China during 2012-2016 and evaluation of selected candidate vaccine strains

• Published in: Poultry science Vol. 97; no. 9; pp. 3023 - 3030
• Main Authors: Xu, C, Ye, H, Qiu, W, Lin, H, Chen, Y, Zhang, H, Liao, M
• Format: Journal Article
• Language: English
• Published: England Poultry Science Association, Inc 01-09-2018
• Subjects: Animals; Chickens; China; Hemagglutinin Glycoproteins, Influenza Virus - genetics; Influenza A Virus, H9N2 Subtype - classification; Influenza A Virus, H9N2 Subtype - immunology; Influenza in Birds - immunology; Influenza Vaccines - immunology; Phylogeny; Poultry Diseases - immunology; Sequence Analysis, RNA; hemagglutinin gene; phylogenetic analysis; H9N2 subtype; Immune protection
• ISSN: 0032-5791; 1525-3171
• DOI: 10.3382/ps/pey154

ABSTRACT
H9N2 subtype avian influenza virus (AIV) was the highly contagious pathogen which has caused severe losses in the poultry industry throughout China in recent years. Using current epidemic viruses as vaccine was an effective way to prevent infection of H9N2 subtype AIV. In this study, a total of 23 H9N2 subtype AIV strains were isolated in 200 samples from 13 provinces of China during 2012-2016. The sequencing and phylogenetic analysis of the hemagglutinin gene sequence of the isolation strains showed that 22 isolation strains were clustered to h9.4.2.5 lineage, while only 1 belonged to h9.4.2.6. The data of cross-HI, neutralization and cross-immune protection shown that the A/chicken/Hunan/HN/2015 (HN) and A/chicken/Shandong/SD/2014 (SD) strains as vaccine could effectively protect present viruses infection compared with other strains. These results indicated that current epidemic viruses were mainly belong to h9.4.2.5 lineage and HN and SD strains as candidate vaccine strains were potentiality for the protection of present H9N2 subtype AIV infection.