一株达菲耐药的甲型H1N1流感病毒全基因特征分析

Characteristics of complete genome of an Oseltamivir-resistant influenza A(H1N1) pdm09 virus

目的分析1株甲型H1N1流感达菲耐药病毒株的全基因特征,为指导流感临床治疗与防控提供依据。方法采用鸡胚进行病毒分离,提取病毒RNA,通过RT-PCR扩增其全基因组8个基因片段,测定核苷酸序列,利用生物信息软件拼接全基因组序列,绘制基因进化树并分析重要基因位点变异情况。结果 A/Fuzhou/SWL11609/2013(H1N1)流感毒株的8个节段基因均处于2013-2014年度进化簇中,且与A/California/07/2009(H1N1)疫苗株高度同源,8个基因同源性均在97.4%以上;其HA和NA基因与A/Hubei-Wuchang/SWL1322/2013(H1N1)达菲耐药株同源性最高,分别为100.0%和99.6%;初步判断该毒株未发生重配现象,其重要致病性基因位点未发生变异;NA基因中具有H275Y典型达菲耐药位点特征,缺失一个糖基化位点(N386K),降低了基因结构的稳定性,同时在V241I和N369K的作用下降低了病毒的适应性。结论本次研究的甲型H1N1流感达菲耐药病毒株表现为低致病性流感病毒特征,但具备较好的人传人能力,需进一步加强监测,谨防耐药株的广泛流行。

Objective To analyze the complete genetic characteristics of an Oseltamivir-resistant influenza A（H1N1）pdm09virus in order to provide a basis for treatment and prevention.Methods The viral RNA was extracted form chicken embryo culture inoculated with throat swab,and genome fragments were amplified by RT-PCR.The PCR products were sequenced and the complete genome sequence was obtained and analyzed via bioinformatics.Results Eight genome fragments of A/Fuzhou/SWL11609/2013（H1N1）were part of viruses cluster（2013-2014）and were closely related to those of A/California/07/2009（H1N1）vaccine strain,with the homologies≥ 97.4%.Nevertheless,its HA and NA genes were similar to the A/Hubei-Wuchang/SWL1322/2013（H1N1）（Oseltamivir-resistant influenza virus）,with a similarity of100.0% and 99.6% respectively.Phylogenetic analysis showed initially that genetic reassortment had not occurred in the virus,neither had mutations at key pathogenic sites,so the virus strain was a low-pathogenic influenza virus.The H275 Ysubstitution was a typical feature of Oseltamivir-resistant genetic mutation.The N386 Ksubstitution resulted in the loss of a glycosylation site in the NA protein,which reduced the stability of gene structure in the presence of the V241 Iand N369Ksubstitutions,causing a negative effect on virus fitness.Conclusion The A/Fuzhou/SWL11609/2013（H1N1）virus was a low-pathogenic influenza virus,but still had the capability of human-to-human transmission,so more attention should be paid to the surveillance in order to control the increasing risk of wide spreading of Oseltamivir-resistant influenza virus.