摘要目的:描述并分析山东省A(H1N1)pdm09亚型流感病毒血凝素(hemagglutinin, HA)基因的多样性，探讨其遗传变异规律，为流感监测、疫情防控和疫苗株匹配度提供科学参考。方法:从GISAID流感数据平台下载2009—2024年流感疫苗推荐株和各分支代表株的HA基因序列，与山东省分离的298株甲型H1N1流感病毒株HA基因序列进行系统发育分析和氨基酸位点变异分析。利用IQ-TREE在线工具的最大似然法(maximum likelihood, ML)构建系统进化树，利用MegAlign软件查看氨基酸位点变异，同时采用NetNGlyc 1.0在线软件预测HA基因潜在的糖基化位点。结果:298株山东省甲型H1N1流感病毒的HA基因同源性为91.2%～100.0%，序列进化分支随时间推移亲缘关系渐远，但进化方向与其他省份大致相同。HA基因氨基酸变异在各年度均有发生，抗原决定簇是其主要变异区域。结论:山东省2009—2024年流感病毒分离株的HA基因仍处于不断进化过程，持续监测流感病毒流行趋势和进化方向对预警流感病毒大流行至关重要。

abstractsObjective:To characterize and analyze the genetic variation of hemagglutinin (HA) of influenza A (H1N1) pdm09 subtype virus in Shandong Province, and explore the genetic variation patterns for providing reference for influenza monitoring, epidemic prevention and control, and vaccine strain selection.Methods:HA gene sequences of the recommended strains of influenza vaccine from 2009 to 2024 and the representative strains of each branch were downloaded from the GISAID Influenza Data Platform, and were phylogenetically analyzed and characterized in terms of amino acid site variation with the HA gene sequences of 298 influenza A (H1N1) virus strains isolated from Shandong Province. A phylogenetic tree was constructed using the maximum likelihood (ML) method of the IQ-TREE online tool, and the amino acid site variants were viewed using MegAlign software. The potential glycosylation sites of the HA gene were predicted using the NetNGlyc 1.0 online software.Results:The HA gene homology of the 298 influenza A (H1N1) viruses isolated in Shandong Province ranged from 91.2% to 100.0%. The evolutionary branches were gradually distantly related over time, but the direction of evolution was roughly the same as that in other provinces. Amino acid mutations in the HA occurred every year and most were found in the antigenic determinants.Conclusions:The HA genes of influenza viruses isolated in Shandong Province from 2009 to 2024 are still in the process of continuous evolution, and continuous monitoring of the epidemiological trends and the evolutionary directions of influenza viruses is essential for early warning of influenza virus pandemics.