2012-2013年湖北省麻疹病毒流行株核蛋白N基因和血凝素蛋白H基因特征分析

Genetic characterization of nucleoprotein and hemagglutinin of measles viruses in Hubei Province from 2012 to 2013

目的 分析近年湖北省麻疹病毒流行株基因型别以及血凝素蛋白（H）基因特性。方法 对2012-2013年麻疹病毒核酸检测阳性的患者标本,直接提取核酸,采用one-step逆转录—聚合酶链反应方法扩增核蛋白（N）和血凝素蛋白（H）基因,测序后进行同源性和进化分析。结果 湖北省麻疹病毒流行株主要为H1基因型的H1a亚型,发现一株D8基因亚型。与中国麻疹疫苗株上海191株的N和H基因比较,其核苷酸同源性分别为91.6%-92.4%和94.6%-94.8%。对湖北省H1a亚型麻疹病毒H基因进化分析发现均属lineage3b,H蛋白序列分析发现第240和第397位氨基酸分别发生Ser→Asn、Pro→Leu的变异。运用贝叶斯中的马尔科夫链的蒙特卡洛方法,估计H1a基因亚型H基因核苷酸的平均碱基替代率为7.619×10-4取代/位点/年,估算其共同祖先大约出现在1980年。结论 湖北省2012-2013年麻疹病毒流行株主要H1a基因型,仅1例D8亚型;与中国疫苗株沪191株相比较,两者在基因特性上存在明显差异,需进一步加强对麻疹病毒基因型别和变异程度的监测。

Objective To analyze the genotypes and molecular characteristics of measles viruses from Hubei province in recent years. Methods Throat swabs of patients infected with measles were collected from 2012 to 2013 and the viral RNA was directly extracted. The Hemagglutinin（ H） and Nucleoprotein（ N） genes were amplified by one-step reverse transcription-polymerase chain reaction and sequenced for homologous and phylogenetic analysis. Results Most of the measles viruses from Hubei belonged to genotype H1 and H1 a subgenotype,only one strain was subgenotype D8. The measles viruses prevailed in Hubei shared higher identity of nucleic acid sequences of N and H genes,respectively. When compared to the China vaccine Shanghai strain 191,there were 91. 6%-92. 4% and 94. 6%-94. 8% indentity of nucleic acid on N and H genes respectively. The phylogenetic analysis of H genes of H1 a subgenotype showed that the measles viruses from Hubei belonged to the lineage 3b. The 240 th and 397 th animo acid of Hemagglutinin protein changed from Ser to Asn and from Pro to Leu,respectively. Bayesian Markov chain Monte Carlo（ MCMC） analysis suggested that annual mean nucleotide substitution rate for H genes of H1 a subgenotype was 7. 619 × 10- 4per site. An estimate of the time of the most recent common ancestor for subgenotype H1 a was approximately 1980. Conclusions The mainly prevalent genotype of measles viruses in Hubei Province is subgenotype H1 a. Only one subgenotype D8 is currently prevalent. Compared with the China vaccine Shanghai strain 191,there are visible differences of N and H genes between the measles viruses prevailed in Hubei and the vaccine strain which suggested that it＇s necessary to further strengthen the monitoring of measles virus genotypes and variation.