中国滇西北地区分离流行性乙型脑炎病毒的分子特征研究

Analysis on the molecular characteristics of Japanese encephalitis virus isolated in Northwestern Yunnan province

目的对中国滇西北地区分离的流行性乙型脑炎（乙脑）病毒进行分子特征研究，了解与云南省内其他地区病毒株的差异。方法用RT-PCR的方法扩增滇西北地区分离的13株乙脑病毒PrM、E片段和3’非编码区，对扩增产物进行序列测定。用Clustal1．8X、DNASTAR、GENEDOC等生物学软件进行核苷酸序列和系统进化分析。结果基于PrM和E基因核苷酸序列的系统进化显示，滇西北分离的13株乙脑病毒中有12株属于基因I型，1株为基因Ⅲ型；12株基因I型乙脑病毒与云南省其他地区分离的病毒株处于不同分支；和云南省其他地区分离株之间E基因核苷酸序列差异度为0．2％～13．9％；3’非编码区存在两种核苷酸缺失情况，基因I型毒株在终止密码子后出现3处缺失，而基因Ⅲ型毒株只有1处缺失。结论滇西北地区乙脑病毒分离株以基因I型为主，E基因核苷酸序列与云南省其他地区分离株差异不明显；基因I型毒株在3’非编码区存在3处缺失，而基因Ⅲ型毒株则只有1处缺失。

Objective To analyze the molecular characteristics of Japanese encephalitis virus （JEV） isolated in Northwestern Yunnan province, and to clarify the differences between the strains isolated in Northwestern and other parts of Yunnan province. Methods PrM, E and 3＇ untranslated region nucleotide acid sequences of the isolates were amplified by RT-PCR and then sequenced. Sequence alignment and phylogenetic analysis were performed by using Clustal 1.8X, DNASTAR, GENEDOC and Mega 3.1 programs. Results 12 of the 13 isolates of JEV obtained in Northwestern Yunnan were identified as genotype I , only one strain was genotype Ⅲ of JEV. The 12 strains of genotype I were clustered in different branches with other isolates obtained in other parts of Yunnan province. Data from sequence analysis on E gene found that the nucleotide identity was 0.2%-13.9% between the Northwestern isolates and other Yurman strains. There were two kinds of nucleotides deletion patterns at 3＇ untranslated region with three and one deletions was found after termination codon in genotype I and Ⅲ isolates, respectively. Conclusion There were two genotypes of I and Ⅲ in 13 strains of JEV in this study and genotype I isolates were predominant （12/13）. There were no apparent differences in E gene sequence between isolates obtained in the Northwestern and other parts of Yunnan. Three deletions were found in 3＇ untranslated region in genotypes I isolates and one deletion was in genotypes Ⅲ.