河南省2010-2011年麻疹野病毒核蛋白基因变异特征分析

Genetic variance of the nucleoprotein gene of measles virus strains in Henan province of China

目的了解河南省流行的麻疹野病毒的基因特征和型别,为制定消除麻疹策略提供依据。方法用非洲绿猴肾细胞/淋巴信号激活因子转染的非洲绿猴肾细胞(Vero/SLAM)从麻疹疑似病例标本中分离麻疹野病毒,用逆转录-聚合酶链反应(RT-PCR)扩增麻疹野病毒分离株的核蛋白(N)基因羧基末端676个核苷酸片段,再对扩增产物进行核苷酸序列测定和分析。以N基因羧基末端450个核苷酸片段构建基因系统进化树,进行遗传距离研究;根据核苷酸序列推导出氨基酸序列,分析氨基酸序列变异情况。结果对2010-2011年分离的49株麻疹病毒进行测序后显示均为H1a基因型,有较高的同源性,大部分序列出现4个核苷酸变异,出现位置在139(G→A)、244(A→G)、298(C→A)、365(G→A)位;推导出的氨基酸序列与H1a基因型比较发现,编码氨基酸422(G→S)、457(S→G)、475(L→I)、497(R→K)位点的变异。结论河南省2010-2011年麻疹野病毒流行优势株为H1a基因型,但存在一定的进化距离,部分分离株氨基酸序列发生突变,呈现多个传播链的流行。

Objective To characterize the genetic features of wild type measles viruses isolated in Henan prov- ince of China from 2010 to 2011. Methods Measles viruses were isolated from the specimens collected from measles suspected cases using the Veto/Slam cell culture system. A 676-nucleotide（nt） long fragment of the carboxyl end of the nueleoprotein gene was amplified by reverse transcription PCR （RT-PCR）. The PCR prod- ucts were sequenced and analyzed. Phylogenetic tree was constructed based on the 450 nucleotides of the car- boxyl end of the nucleoprotein gene. The distance between the isolated virus and the reference virus was further analyzed and the amino acid （aa） sequence was deducted accordingly. Results Fourty-nine strains of wild type measles viruses were isolated in Henan province from 2010 to 2011 and all were identified as Hla geno- type. Comparing to the reference sequence, most of the strains in our study showed nucleotide variances in 4 positions that lead to the changes in the deducted amino acid sequence. The positions of nucleotide（nt） and the corresponding amino acid （aa） were 139 nt （G to A） /422 aa （G to S）, 244 nt （A to G） /457 aa （S to G）, 298 nt （Cto A） /475 aa （LtoI）, 365 nt （Gto A） /497 aa （R to K）. Conclusions The genotype of measles virus circulating in Henan province from 2010 to 2011 is Hla with amino acid variations at 4 locations in the nucleoptorein gene.