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Journal of Integrative Agriculture  2023, Vol. 22 Issue (3): 881-896    DOI: 10.1016/j.jia.2022.08.114
Animal Science · Veterinary Medicine Advanced Online Publication | Current Issue | Archive | Adv Search |

Phylogenetic and epidemiological characteristics of H9N2 avian influenza viruses in Shandong Province, China from 2019 to 2021

ZHAO Yi-ran1*, ZHAO Yu-zhong1*, LIU Si-dang1, XIAO Yi-hong1, LI Ning1, LIU Kui-hao1, MENG Fan-liang1, ZHAO Jun1, LIU Meng-da2#, LI Bao-quan1#

1 College of Animal Science and Veterinary Medicine, Shandong Agricultural University/Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong Agricultural University, Tai’an 271018, P.R.China

2 Division of Zoonoses Surveillance, China Animal Health and Epidemiology Center, Qingdao 266033, P.R.China

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H9N2禽流感病毒(AIV)已在全球家禽中广泛流行,并在人类和哺乳动物中引起零星的感染。本研究旨在了解H9N2AIV的遗传进化和流行病学特征。2019-2021年,从中国山东省采集136份疑似AI感染的鸡的组织样品,共分离出11株H9N2AIV。遗传进化分析表明,分离出的11株H9N2AIV的8个基因片段与欧亚谱系的几个亚谱系密切相关:BJ/94-like分支(HA和NA基因)、G1-like分支(PB2和M基因)、SH/F/98-like分支(PB1、PA、NP和NS基因)。所有分离病毒HA蛋白的裂解位点仅含有一个碱性氨基酸,表明它们都属于低致病性AIV。分离株表现出优先与类人受体 (HA) 结合和哺乳动物适应性(PB2、PB1和PA)的突变位点,从而增加了它们跨越物种屏障并引起人类感染的风险。此外,11株H9N2AIV还存在抗原位点和耐药性位点的突变,说明应及时评估疫苗的有效性,加强抗流感药物的研发。小鼠感染显示,4株H9N2AIV的致病性水平不同。从中国山东省采集的7237份鸡血清样品中,HI抗体平均滴度为8.49 log2,离散度为23.56%,抗体合格率为98.52%4 1og2),表明山东省规模化养鸡场对H9N2AI的整体免疫效果较好。基于我们的结果,应该加强对H9N2AIV的流行病学监测。


H9N2 avian influenza virus (AIV) has widely circulated in poultry worldwide and sporadic infections in humans and mammals.  During our surveillance of chicken from 2019 to 2021 in Shandong Province, China, we isolated 11 H9N2 AIVs.  Phylogenetic analyses showed that the eight gene segments of the 11 isolates were closely related to several sublineages of Eurasian lineage: BJ/94-like clades (HA and NA genes), G1-like clades (PB2 and M genes), and SH/F/98-like clades (PB1, PA, NP and NS genes).  The isolates showed mutation sites that preferentially bind to human-like receptors (HA) and mammalian fitness sites (PB2, PB1 and PA), as well as mutations in antigen and drug resistance sites.  Moreover, studies with mice revealed four isolates with varying levels of pathogenicity.  The average antibody titer of the H9N2 AIVs was 8.60 log2.  Based on our results, the epidemiological surveillance of H9N2 AIVs should be strengthened.

Keywords:  influenza virus       phylogenetic analyses        mutation sites        pathogenicity        antibody titer        epidemiological surveillance  
Received: 31 December 2021   Accepted: 24 June 2022

About author:  ZHAO Yi-ran, E-mail:; ZHAO Yu-zhong, E-mail:; #Correspondence LI Bao-quan, E-mail:; LIU Meng-da, E-mail: * These authors contributed equally to this study.

Cite this article: 

ZHAO Yi-ran, ZHAO Yu-zhong, LIU Si-dang, XIAO Yi-hong, LI Ning, LIU Kui-hao, MENG Fan-liang, ZHAO Jun, LIU Meng-da, LI Bao-quan. 2023.

Phylogenetic and epidemiological characteristics of H9N2 avian influenza viruses in Shandong Province, China from 2019 to 2021 . Journal of Integrative Agriculture, 22(3): 881-896.

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