China Animal Husbandry & Veterinary Medicine ›› 2025, Vol. 52 ›› Issue (9): 4358-4367.doi: 10.16431/j.cnki.1671-7236.2025.09.032

• Preventive Veterinary Medicine • Previous Articles    

Molecular Characterization of HA and NA Genes of H3N2 Subtype Avian Influenza Viruses in Guangxi During 2020 to 2024

YIN Yanwen1, XIONG Chenyong2, WEI Wei1, SHI Kaichuang1, ZHENG Min1, CUI Pengfei3, WEI Xiankai1, LI Zhiyuan4, LIU Huixin4, FENG Shuping1, LU Chunhua1, QU Sujie1, LU Wenjun1, LI Xuezhen5, WANG Ruimin6, DENG Guohua3, OU Changbo4   

  1. 1. Guangxi Center for Animal Disease Control and Prevention, Nanning 530001, China;
    2. Guangxi State Farms Yongxin Animal Husbandry Group Longbei Animal Husbandry Co., Ltd., Chongzuo 532400, China;
    3. Animal Influenza Laboratory of Ministry of Agriculture and Rural Affairs, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China;
    4. College of Animal Science and Technology, Guangxi University, Nanning 530005, China;
    5. Baise Center for Animal Disease Control and Prevention, Baise 533000, China;
    6. Guangxi Buffalo Research Institute, Nanning 530001, China
  • Received:2024-12-14 Published:2025-08-29

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Abstract: 【Objective】 The experiment was conducted to explore the molecular genetic evolution characteristics of H3N2 subtype Avian influenza virus (AIV) strains in Guangxi. 【Method】 Disease samples of poultry throat swabs and anal swabs from various places in Guangxi from 2020 to 2024 were collected,and the H3N2 subtype AIV was identified and detected by Real-time quantitative RT-PCR.Some positive samples were selected and inoculated into SPF chicken embryos through the allantoic cavity,and the allantoic fluid of chicken embryos was collected.After extracting nucleic acids,hemagglutinin (HA) and neuraminidase (NA) genes were amplified by PCR and sequenced,and analyses of sequence similarity,phylogenetic,amino acid variation sites and genetic evolution rate were conducted. 【Result】 A total of 43 HA and NA gene sequences were obtained,with the coding region sizes of 1 701 and 1 410 bp,respectively.The similarity comparison analysis showed that the nucleotide sequence similarities between HA and NA genes obtained in this study were 86.0%-99.9% and 89.7%-99.9%,respectively.The similarities of nucleotide sequences with avian,human,porcine and canine sources in GenBank were 78.4%-99.7% and 78.1%-99.1%,respectively.HA and NA genes of H3N2 subtype AIV in Guangxi belonged to the Eurasian lineage,which was most closely related to avian origin and most closely related to human/porcine origin.Glycosylation occured at amino acids 18-20,22-24,38-40,54-56,61-63,181-183,301-303 and 499-501 of HA protein，and occured at amino acids 61-63,69-71,86-88,143-145,146-148,200-202,234-236,313-315 and 402-404 of NA protein.Some amino acid sites had undergone variations.HA protein was cleaved at sites 340PEKQTR↓GLF348 and 340PERQTR↓GLF348.Genetic evolution rate estimation showed that the genetic evolution rates of HA and NA genes were 3.26×10-3 and 3.67×10-3 substitutions/(site·year),respectively,and the population size of HA gene showed different dynamic evolution characteristics in various periods. 【Conclusion】 The current epidemic strains of H3N2 subtype AIV in Guangxi were closely related to the homologous epidemic strains,some HA and NA proteins havd unique amino acid mutations,and the evolutionary trend of strains of different genera was inconsistent with the characteristics of genetic diversity,which providing basic data for prevention and control of H3N2 subtype AIV.

Key words: Avian influenza virus; H3N2 subtype; genetic evolution; similarity

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