2017—2018年北京市东城区新甲型H1N1流感病毒HA基因特征研究

Study on HA genetic characteristics of new influenza A(H1N1)virus in Dongcheng District of Beijing from 2017-2018

目的了解2017年4月1日—2018年3月31日期间北京市东城区新甲型H1N1流感病毒流行特征,并分析细胞株和鸡胚株血凝素(HA)基因遗传变异情况。方法收集2017年4月1日—2018年3月31日期间北京市东城区流感数据,分析新甲型H1N1流感的流行特征;用实时荧光PCR(RT-PCR)方法对选取的7株新甲型H1N1细胞分离株和其相对应的7株鸡胚株进行HA基因序列扩增并测序,用DNASTAR 5.0和MEGA 6.0软件对测序结果进行系统进化树和遗传特征分析。结果2017年4月1日—2018年3月31日期间在北京市东城区共检测样本1780份,新甲型H1N1阳性99份,阳性率是5.56%,细胞分离出新甲型H1N1为51株,鸡胚株为15株。测序成功的13株毒株与世界卫生组织(WHO)推荐的北半球疫苗株A/Michigan/45/2015(甲型/密歇根/45/2015)在系统进化树上位于同一大分支上,同源性较高。其核苷酸同源性为98.96%~100.00%,氨基酸同源性为97.92%~100.00%。其中S74R、P137S、S164T、S183P、T185N、T216K、I267T共7个氨基酸位点(包含抗原决定簇位点)发生改变,决定流感毒力的D222位点和二硫键未发生改变。结论目前北京市东城区新甲型H1N1流感病毒与疫苗株匹配性较高,但是其HA序列中氨基酸位点变异仍存在,要长期从分子水平进行监测,预防新甲型H1N1流感发生大流行。

Objective To understand the epidemic characteristics of new influenza A(H1N1)virus in Dongcheng District of Beijing from April 1,2017 to March 31,2018,analyze the variation of hemagglutinin(HA)gene of cell strains and the chicken embryo virus strains.Methods The influenza data in Dongcheng District of Beijing from April 1,2017 to March 31,2018 were collected to analyze the epidemic characteristics of the new influenza A(H1N1).The HA gene sequence of the selected seven influenza A(H1N1)cell strains and their corresponding seven chicken embryo strains were amplified and sequenced by the real-time fluorescent PCR(RT-PCR).The phylogenetic tree and inheritance characteristics were analyzed by DNASTAR 5.0 and MEGA 6.0 software.Results Totally 1780 samples were detected in Dongcheng District of Beijing from April 1,2017 to March 31,2018.99 samples were positive for new influenza A(H1N1),with a positive rate of 5.56%.51 cell strains and 15 chicken embryo strains were isolated.13 successfully sequenced strains and the northern hemisphere vaccine strain A/Michigan/45/2015 recommended by the World Health Organization(WHO)were located on the same branch of phylogenetic tree and had the higher homology.The nucleotide homology was 98.96%-100.00%and the amino acid homology was 97.92%-100.00%.Among them,seven amino acid sites(including antigenic determinant sites)of S74 R,P137 S,S164 T,S183 P,T185 N,T216 K,I267 T were changed,while the D222 site and disulfide bonds that determined the virulence of influenza had not changed.Conclusion At present,the new influenza A(H1N1)virus in Dongcheng District of Beijing are well matched with the vaccine strain,but the mutation of amino acid sites in the HA gene sequence still exists,which needs to be monitored from the molecular level for a long time to prevent the pandemic of new influenza A(H1N1).