Minxiu Zhang 1,2 , Sisi Luo 2 , Zhixun Xie 2,* , Meng Li 2 , Liji Xie 2 , Qing Fan 2 , Can Wang 2 , Tingting Zeng 2 , Hongyu Ren 2 , Xiaofeng Li 2 , Lijun Wan 2 , Zhihua Ruan 2 , Aiqiong Wu 2 , Bingyi Yang 2 , Houxun Ya 2 and Ting-Rong Luo 1,*
1 College of Animal Sciences and Veterinary Medicine, Guangxi University, Nanning 530004, China; zhminxiu2010@163.com
2 Key Laboratory of China (Guangxi)-ASEAN Cross-Border Animal Disease Prevention and Control, Ministry of Agriculture and Rural Affairs, Guangxi Key Laboratory of Veterinary Biotechnology, Guangxi Veterinary Research Institute, 51 Youai North Road, Nanning 530001, China
* Correspondence: xiezhixun@126.com (Z.X.); tingrongluo@gxu.edu.cn (T.-R.L.)ABSTRACT H9N2 avian influenza virus (AIV) is widely prevalent in poultry in China. To understand the genetic characteristics and evolution of H9N2 AIVs in Guangxi, southern China, the complete genomes of H9N2 AIVs from 1999–2023 were systematically analysed. Maximum likelihood (ML) trees indicated that H9N2 AIV gene sublineage diversity contributed to genotype diversity, yielding 17 genotypes (G1–G17). Since 2010, genotype G14 (also known as genotype S or G57) has become predominant in poultry in Guangxi. Phylogenetic analysis in the HA has resulted in the distancing of recent Guangxi isolates from the vaccine strains. This study also revealed that the genotypes of H9N2 AIVs infecting swine, equines and canines in Guangxi were consistent with those found in avian species at the same time, highlighting the capacity of H9N2 AIVs to be transmitted across species. The antigenic residues in the HA head region and NA protein of the Guangxi isolates from 2020–2023 changed significantly compared to the vaccine strains, suggesting possible antigenic drift in these viruses. Amino acid analysis of the HA protein revealed that 84.9% (73/86) of H9N2 AIV isolates from Guangxi, including those from live poultry markets, preferentially bound to α-2,6 sialic acid receptors. Considerable attention should be given to cross-species transmission of H9N2 AIV in the region. On the basis of these findings, strengthening the monitoring of H9N2 AIV in poultry in Guangxi is essential.
KEYWORDS H9N2 AIV; Guangxi; molecular evolution; genotype; gene sublineages
Microorganisms. 2025 Nov 12;13(11):2579. doi: 10.3390/microorganisms13112579.