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目的了解北京地区严重急性呼吸道感染(SARI)病例中甲型流感病毒进化特征。方法选择2014-2016年SARI病例分离A(H3N2)亚型流感病毒毒株32株,提取病毒RNA,使用Ion Torrent PGM二代测序仪进行了病毒全基因组测序。使用Mega、Consurf等软件对毒株各个基因进行了分子进化分析和分子特征分析。结果 18株2014-2015年流行季毒株的血凝素(HA)基因属于3C.3a分支,而14株2015-2016年流行季毒株HA基因属于3C.2a分支。在32株测定株HA基因中共发现7个氨基酸位点变异,其中2个位于抗原决定簇。对神经氨酸酶基因和基质蛋白基因进行分析显示,所有的测定株均对M2离子通道抑制剂药物耐药,而对神经氨酸酶抑制剂药物敏感。结论 2014-2016年SARI病例分离A(H3N2)亚型毒株的基因特征与同时期北京地区流行株基本一致。两个流行季间出现了较为明显的抗原漂移,相对于同流行季疫苗株存在一定程度的变异。
Objective To understand the evolutionary characteristics of influenza A virus in severe acute respiratory infection (SARI) cases in Beijing. Methods Thirty-two strains of A (H3N2) subtype influenza viruses were isolated from SARI cases in 2014-2016. The viral RNA was extracted and the whole genome of the virus was sequenced using the Ion Torrent PGM second-generation sequencer. Using Mega, Consurf and other software, the molecular evolution analysis and molecular characterization analysis of each gene were carried out. Results The hemagglutinin (HA) gene of 18 strains of epidemic strain from 2014-2015 belonged to 3C.3a branch, while 14 strains of HA gene from 2015-2016 epidemic virulent strain belonged to 3C.2a branch. A total of seven amino acid site variations were found in the HA gene of 32 strains, two of which were located in the antigenic determinant. Analysis of neuraminidase and matrix protein genes showed that all the tested strains were resistant to M2 ion channel inhibitor drugs and sensitive to neuraminidase inhibitors. Conclusion The genetic characteristics of A (H3N2) subtype isolates from SARI cases in 2014-2016 are basically the same as that of the epidemic strains in Beijing during the same period. There were obvious antigenic drift during the two popular seasons, which showed a certain degree of variation compared with the same seasonal quarantine vaccine strains.