Zhao Yuzhong, Han Lebin, Sang Haotian, Yang Pingping, Hou Yanmeng, Xiao Yihong
College of Animal Science and Veterinary Medicine, Shandong Agricultural University, Tai'an, China.
Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong Agricultural University, Tai'an, China.
Front Cell Infect Microbiol. 2024 Dec 16;14:1517023. doi: 10.3389/fcimb.2024.1517023. eCollection 2024.
Swine influenza virus (SIV) is a highly contagious pathogen that poses significant economic challenges to the swine industry and carries zoonotic potential, underscoring the need for vigilant surveillance. In this study, we performed a comprehensive genetic and molecular analysis of H3N2 SIV isolates obtained from 372 swine samples collected in Shandong Province, China. Phylogenetic analysis revealed two distinct genotypes. The surface genes of both genotypes clustered with the human-like H3N2 lineage, while the internal genes of one genotype clustered with the 2009 pandemic H1N1 (pdm/09) lineage. In the second genotype, the NS gene clustered with the classical swine (CS) H1N1 lineage, while the remaining internal genes clustered with pdm/09, suggesting stable integration of pdm/09 gene segments into H3N2 SIV. Homology analysis showed over 96% genetic similarity between the isolates and reference strains from China and Brazil, suggesting potential transmission through swine trade or human movement. Molecular characterization identified amino acid substitutions in the HA protein (190D, 226I, and 228S), potentially enhancing the virus's affinity for human-like receptors, thereby increasing the zoonotic risk. Key mutations in the PB2 (271A, 591R), PA (336M, 356R, 409N), and M2 (S31N) proteins, along with novel drug resistance mutations, indicate the potential for enhanced virulence and drug resistance in these isolates. Moreover, glycosylation site analysis revealed four differences, and antigenic site analysis showed 13 differences between the HA proteins of the isolates and the WHO-recommended vaccine strain A/Cambodia/E0826360/2020 for the 2021-2022 season, which may reduce vaccine efficacy. Serological analysis revealed that 11 out of the tested serum samples were positive for H3N2 antibodies, resulting in an overall positivity rate of 0.42%. These findings emphasize the urgent need for strengthened SIV surveillance in China to monitor the risk of human transmission and ensure better preparedness for future influenza outbreaks.
猪流感病毒（SIV）是一种高度传染性的病原体，给养猪业带来了重大经济挑战，并具有人畜共患病传播的潜在风险，这凸显了进行 vigilant surveillance 的必要性。在本研究中，我们对从中国山东省采集的 372 份猪样本中获得的 H3N2 SIV 分离株进行了全面的基因和分子分析。系统发育分析揭示了两种不同的基因型。两种基因型的表面基因均与类人 H3N2 谱系聚类，而其中一种基因型的内部基因与 2009 年大流行 H1N1（pdm/09）谱系聚类。在第二种基因型中，NS 基因与经典猪（CS）H1N1 谱系聚类，而其余内部基因与 pdm/09 聚类，这表明 pdm/09 基因片段已稳定整合到 H3N2 SIV 中。同源性分析表明，这些分离株与来自中国和巴西的参考毒株之间的遗传相似性超过 96%，这表明可能通过猪贸易或人员流动传播。分子特征鉴定发现 HA 蛋白中存在氨基酸替换（190D、226I 和 228S），这可能增强病毒对类人受体的亲和力，从而增加人畜共患病传播风险。PB2（271A、591R）、PA（336M、356R、409N）和 M2（S31N）蛋白中的关键突变以及新的耐药性突变表明这些分离株具有增强的毒力和耐药性的可能性。此外，糖基化位点分析揭示了四个差异，抗原位点分析表明这些分离株的 HA 蛋白与世界卫生组织推荐的 2021 - 2022 季节疫苗株 A/柬埔寨/E0826360/2020 之间存在 13 个差异，这可能会降低疫苗效力。血清学分析显示，在检测的血清样本中有 11 份 H3N2 抗体呈阳性，总体阳性率为 0.42%。这些发现强调了中国迫切需要加强 SIV 监测，以监测人传人的风险，并确保为未来的流感爆发做好更好的准备。
