College of Veterinary Medicine, Yunnan Agricultural University, Kunming 650201, China; Center for Poultry Disease Control and Prevention, Yunnan Agricultural University, Kunming 650201, China.
Animal Husbandry and Veterinary Bureau, Yanjin 657599, China.
Poult Sci. 2024 Sep;103(9):104040. doi: 10.1016/j.psj.2024.104040. Epub 2024 Jun 28.
The H9N2 subtype of the avian influenza virus (AIV) is widely prevalent in birds, threatening the poultry industry and providing genetic material for emerging human pathogens. The prevalence and genetic characteristics of H9N2 in Yunnan Province, China, are largely unknown. Samples were collected from live poultry markets (LPMs) and breeding farms in Yunnan Province. H9N2-positive samples were identified by polymerase chain reaction (PCR), with a high positivity rate of 42.86% in tissue samples. The positivity rate of swab samples in the LPMs in Kunming was 3.97% (17/564), but no AIV was detected in samples from poultry farms in Lijiang, Wenshan, and Yuxi. Evolutionary analysis and genotyping were performed for the 17 strains of isolated H9N2 virus. Phylogenetic analysis revealed that all H9N2 viral genes had 91.6%-100% nucleotide homology, belonged to the G57 genotype, and had high homology with H9N2 viruses isolated from Guangdong and Guangxi, suggesting that the H9N2 viruses in Yunnan Province may have been imported by chicks. Using a nucleotide divergence cutoff of 95%, we identified ten distinct H9N2 genotypes that continued to evolve. The surface genes of the H9N2 isolates displayed substantial genetic diversity, highlighting the genetic diversity and complexity of the H9N2-subtype AIVs in Yunnan. Molecular analysis demonstrated that all 17 strains of H9N2 isolates had mutations at H183N, Q226L, L31P, and I268V in hemagglutinin; S31N in matrix protein 2; and no replacements at positions 274 and 292 of the neuraminidase protein. Sixteen strains had the A558V mutation and one strain had the E627V mutation in polymerase basic protein 2. Analysis of these amino acid sites suggests that H9N2 influenza viruses in Yunnan continue to mutate and adapt to mammals and are sensitive to neuraminidase inhibitors but resistant to adamantanes. It is necessary to strengthen surveillance of AIV H9N2 subtypes in poultry and LPMs in Yunnan to further understand their genetic diversity.
H9N2 亚型禽流感病毒（AIV）广泛存在于禽类中，对家禽业构成威胁，并为新兴人类病原体提供了遗传物质。中国云南省 H9N2 的流行情况和遗传特征在很大程度上尚不清楚。本研究从云南省的活禽市场（LPM）和养殖场采集了样本。通过聚合酶链反应（PCR）鉴定 H9N2 阳性样本，组织样本的阳性检出率高达 42.86%。昆明 LPM 拭子样本的阳性检出率为 3.97%（17/564），但在丽江、文山和玉溪的家禽养殖场未检出 AIV。对分离的 17 株 H9N2 病毒进行了进化分析和基因分型。系统进化分析显示，所有 H9N2 病毒基因的核苷酸同源性为 91.6%-100%，属于 G57 基因型，与广东和广西分离的 H9N2 病毒高度同源，提示云南省的 H9N2 病毒可能是由雏鸡传入的。使用核苷酸差异截断值为 95%，我们鉴定了 10 种不同的 H9N2 基因型，这些基因型仍在继续进化。H9N2 分离株的表面基因显示出显著的遗传多样性，突出了云南省 H9N2 亚型 AIV 的遗传多样性和复杂性。分子分析表明，17 株 H9N2 分离株的血凝素中均有 H183N、Q226L、L31P 和 I268V 突变，基质蛋白 2 中有 S31N 突变，神经氨酸酶蛋白无 274 和 292 位替换。16 株有聚合酶碱性蛋白 2 的 A558V 突变，1 株有 E627V 突变。对这些氨基酸位点的分析表明，云南省的 H9N2 流感病毒仍在不断突变和适应哺乳动物，对神经氨酸酶抑制剂敏感，但对金刚烷胺类药物耐药。有必要加强对云南省家禽和 LPM 中 AIV H9N2 亚型的监测，以进一步了解其遗传多样性。
