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目的了解2007—2010年天津市流感流行特点及季节性流感H3N2亚型HA1基因变异特性。方法采用MDCK细胞培养法分离流感病毒,选取14株H3亚型流感毒株进行RT-PCR扩增HA1片段,产物纯化后进行核苷酸序列测定,测定结果与WHO全球流感疫苗株序列进行同源比对,绘制种系发生树。结果采集咽拭子标本4 220份,分离出流感毒株894株,总检出率为21.2%,其中H1亚型、H3亚型、B型作为优势型交替出现。氨基酸序列分析显示H3亚型流感HA1基因随时间推移不断发生点突变,2007年初分离株有6个主要位点变异,并延续下来;2009—2010年在抗原决定簇A和B区又有4个新位点变异;种系发生树分为两支,2009—2010年的毒株产生遗传距离单成一支,而其余毒株与同期疫苗株在一分支。结论天津地区同时存在H3N2亚型、H1N1亚型、B型和新甲型H1N1流感病毒,并交替流行;H3亚型已发生抗原性漂移并有增强的趋势。
Objective To understand the epidemiological characteristics of influenza in Tianjin from 2007 to 2010 and the variation of HA1 gene of H3N2 subtype in seasonal influenza. Methods The influenza virus was isolated by MDCK cell culture, and 14 strains of H3 subtype were selected to amplify the HA1 fragment by RT-PCR. The product was purified and then sequenced. The results were homologous to the WHO influenza vaccine strain Compare, draw the phylogenetic tree. Results A total of 4 220 pharyngeal swab specimens were collected and 894 influenza strains were isolated. The total detection rate was 21.2%. Among them, H1 subtype, H3 subtype and B type were predominantly alternated. Amino acid sequence analysis showed that HA1 gene of H3 subunit constantly mutated point by point with the passage of time. In early 2007, the isolates had 6 major site variation and continued; in 2009-2010, there were 4 The new site was mutated; the phylogenetic tree was divided into two branches. The genetic distance from 2009 to 2010 was single, while the remaining strains were in one branch with the same vaccine strain. Conclusion The H3N2, H1N1, B and H1N1 influenza viruses co-exist in Tianjin. The H3 subtype is antigenic and has an increasing trend.