一起学校甲型H1N1流感聚集疫情的流行特征和全基因组测序分析

目的 了解济宁市一起聚集流感疫情的甲型H1N1流感病毒全基因组特征,为甲型H1N1流感防控提供依据。方法 对在一起聚集流感疫情采集的12份患者咽拭子标本进行流感病毒实时荧光定量PCR法核酸检测,对阳性标本进行病毒培养和全基因组测序,利用DNASTAR软件分析核苷酸和氨基酸同源性,利用MEGA软件构建进化树,利用NetNGlyc、GPS-SUMO、NetPhos软件分别分析糖基化位点、类泛素蛋白修饰分子化位点和磷酸化位点。结果 12份咽拭子标本中,4份标本甲型H1N1流感病毒核酸检测阳性,分离流感病毒株4株。同2018—2019年度北半球疫苗株A/Brisbane/02/2018相比,8个基因节段核苷酸同源性范围为98.5%~99.8%;编码的10种蛋白氨基酸同源性范围为98.2%~100.0%。在进化树上,4株毒株位于两个进化簇,其中3株毒株位于同一进化簇,1株毒株位于不同进化簇。4株毒株编码的10种蛋白共发生50处氨基酸位点置换,血凝素蛋白抗原表位2个氨基酸位点发生置换,神经氨酸酶蛋白酶活性位点和神经氨酸酶抑制剂耐药位点均未发生变异,聚合酶酸性蛋白、聚合酶碱性蛋白1和聚合酶碱性蛋白2抑制剂耐药位点均未发生变异。结论 本次由甲型H1N1流感病毒引起学校流感聚集疫情有2个不同的源头,应加强对学校流感聚集疫情监测,加强学校流感防控。

Analysis of the epidemiological characteristics and the whole genome characteristics of influenza A (H1N1) pdm09 virus outbreak in a school

Objective To analyze the whole genome characteristic of influenza A(H1N1) pdm09 virus outbreak in a school in Jining, so as to serve as a reference for prevention and control of influenza A (H1N1) pdm09．Methods Real time fluorescence quantitative PCR were used to detected the 12 nasopharyngeal swab specimens from patients. The positive specimens were cultured and sequenced the whole genome. DNASTAR was used to analyze the homology. MEGA was used to construct the phylogenetic tree. NetNGly, GPS-SUMO, NetPhos were used to predict the glycosylation sites, the small ubiquitin-like modifier sites and the phosphorylation sites respectively. Results Among of 12 specimens, 4 specimens were showed positive for influenza A (H1N1) pdm09 virus nucleic acid, and 4 virus strains were isolated. Compared to the vaccine strain A/Brisbane/02/2018, the homology of nucleic acids of 8 gene segments was 98.5%-99.8%. The homology of amino acids of 10 proteins was 98.2%-100%. In the evolutionary tree analysis, four strains were located in two evolutionary clusters, three strains in the same evolutionary cluster and one strain in a different evolutionary cluster. A total of 50 amino acid site substitutions occurred in the 10 proteins encoded by the four strains, including two amino acid sites in the hemagglutinin antigen epitope, and there was no mutation in the neuraminidase (NA) protease active site, polymerase acidic protein (PA), polymerase basic protein 1 (PB1) and polymerase basic protein 2 (PB2) inhibitor resistance sites, and neuraminidase inhibitor resistance sites. In addition, the glycosylation sites and SUMO sites were not mutated, while multiple phosphorylation sites were substituted. Conclusions There are 2 different sources of influenza A (H1N1) virus causing the school influenza outbreak. School influenza outbreak surveillance and school influenza prevention and control should be strengthened should be enhanced.