浙江省2005-2010年风疹病毒分子流行病学研究

Molecular epidemiological study on rubella virus strains isolated in Zhejiang province, China, 2005-2010

目的分析2005--2010年浙江省风疹病毒流行株的病原学与分子流行病学特征。方法采集该期间风疹疫情中的疑似患者标本，于Vero细胞上分离病毒。采用巢式RT-PCR扩增流行株E1、E2和C三个结构基因片段，对扩增产物进行序列测定与分析。结果从52例临床标本中共分离到风疹病毒流行株7株，除RVi／Zhejiang．CHN／23．08株为2B基因型外，其余6株均属于1E基因型。基因进化树上，1E基因型流行株分别与香港、海南地区流行株具有最近亲缘关系，而2B基因型流行株与BuenosAires．ARG／46．08位于同一分支。遗传距离分析表明，浙江2B型流行株与全球其他地区流行株间的遗传距离（0．011）小于与中国流行株（0．023）间的遗传距离。浙江风疹流行株与中国风疹疫苗株BRDⅡ在核苷酸水平上的同源性为C〉E2〉E1，而氨基酸水平上的同源性为E1〉C〉E2，对应存在3、11和23个氨基酸的变异。各位点氨基酸熵值表明，E1蛋白上仅存在一个易变位点（熵值〉0．600），而E2蛋白上有7个易变异位点和1个高变异位点（熵值〉1．000）。结论2005--2010年浙江省存在两种基因型风疹病毒流行，1E为优势基因型，2B可能为境外输入株。流行株E1基因氨基酸序列相对保守，而E2基因氨基酸变异较大，在风疹病毒流行病学监测中除关注E1基因外，应开展对结构基因E2和C的研究。

Objective To analyze the molecular epidemiological characteristic of rubella virus strains isolated in Zhejiang province from 2005 to 2010, to provide basic data for rubella prevention and control. Methods Rubella virus strains were isolated on Vero cells from the suspected patients＇ specimens collected in Zhejiang province during 2005 to 2010. Partial fragments of the structural gene of Zhejiang rubella strains were amplified, using nested reverse transcriptionpolymerase chain reaction （RT-PCR）. The amplified products were sequences and analyzed. Results In total, 7 rubella strains were isolated from 52 clinical specimens, of which six were classified as genotype 1E and only one was characterized as genotype 2B. In the phylogenetic tree, the Zhejiang 1E genotype rubella strains were located in the same branches with Hongkong or Hainan isolates respectively, but the Zhejiang 2B genotype strain were located in the same branch with oversea strain BuenosAires.ARG/46.08. Through p-distance analysis, results also showed that the Zhejiang 2B genotype strain was closer to the 2B strains isolated from overseas （0.011） than those strains from other provinces of China （0.023）. Compared with Chinese vaccine strain BRD U, the homology on three structural genes was C〉E2〉E1, but the homology of deduced amino acid sequence was E1 〉C〉E2, with corresponding 3,11 and 23 amino acid mutations. There was only one amino acid on E1 gene with entropy value higher than 0.600, but seven sites on E2 gene with entropy value appeared higher than 0.600 and one with entropy value higher than 1.000. Conclusion Two genotypes of rubella virus had circulated in Zhejiang province during 2005 to 2010. Genotype 1E appeared to be the predominant genotype and 2B being an imported one. Amino acid sequence of El gene from Zhejiang rubella strains was comparatively conserved, but E2 gene was hypervariable. Study on rubella virus E2 and C gene should be conducted in the epidemiological surveillance program of rubella.