昆明市病毒性脑炎病例中埃可病毒6型分离株的VP1编码序列基因特征分析

Genetic characteristic analysis of echovirus 6 isolated from viral meningitis cases in Kunming of China

目的对2010-2014年昆明市病毒性脑炎病例中分离的4株埃可病毒6型(echovirus 6,E6)VP1编码序列特征进行分子流行病学分析。方法对昆明市2010-2014年传染病重大专项脑炎综合征实验室监测系统分离到的4株E6病毒的VP1区基因进行基因扩增和测序;按参考文献下载基因库中E6病毒VP1编码序列参考序列,用MEGA5.1软件计算不同毒株的核苷酸和氨基酸差异率,并构建系统进化树,进行VP1编码序列特征和分子流行病学分析。结果 2010-2014年云南省病毒性脑炎病例中分离到的103份肠道病毒中共检出E6病毒4株,占3.88%(4/103),E6病毒的阳性总检出率为0.29%(4/1 376)。VP1编码序列特征分析表明,云南4株E6毒株均为C2基因亚型(genotype C2)。结论除原型株为A基因型外,其他E6毒株可分为3个基因型(基因型B、C和D),C基因型又分为4个亚型,云南分离株分布在C2基因亚型,且2010年和2011年的云南分离株与部分山东地区的分离株较为接近,而2013年和2014年的云南分离株自成一簇,为云南省特有的亚型,该病毒可能在昆明地区存在小范围流行。

Objective To analyze the genetic characteristics of echovirus 6 （E6） isolated from viral meningitis （VM） cases in Kunming of China. Methods RT-PCR and VP1 gene sequencing were done for the 4 E6 strains isolated from VM surveillance system during 2010 and 2014. VP1 gene sequences of E6 reference strains were downloaded from GenBank. Nucleotide （nt） and amino acid （aa） diversities were calculated and the phylogenetic tree was constructed using MEGA 5.1 software. Results From 2010 to 2014, 4 strains of E6 viruses were detected from 103 EVs, accounting for 3.88% （4/103）, the overall positive rate was 0.29 % （4/ 1 376）. Phylogenetic analysis showed that all 4 Yunnan E6 isolates belong to genotype C, C2 sub-genotypes. Conclusions The 2010 and 2011 isolates showed the highest homology with some Shandong isolates, and the other two 2013 and 2014 isolates were clustered as Yunnan unique branch. These two strains showed similar evolutionary characteristics.