福建省2005-2008年临床乙脑病毒分离株的序列分析

Sequence analysis of clinical Japanese encephalitis viruses isolated from Fujian,2005-2008

目的分析2005-2008年福建乙脑病毒毒株的部分基因组序列,探索乙脑病毒临床分离株的变异和进化。方法临床标本(血清或脑脊液)接种BHK-21细胞,分离乙脑病毒,从培养液上清提取病毒RNA,RT-PCR扩增病毒基因组片段,并进行克隆、测序以及序列分析。结果共分离到5株乙脑病毒。对病毒C/prM区240bp和全长E基因的序列分析表明,近几年的这些临床分离株基因型仍然全部属于G3型。种系发生分析结果显示,新分离株与2002、2003年分离株存在较大同源性。虽然病毒E基因存在少量氨基酸改变,但总体上这些变异不足以影响病毒的致病性。结论近几年福建省的临床乙脑病毒分离株为G3型,新分离株亲缘关系比较接近2002、2003年毒株。

Japanese encephalitis virus （JEV） is an important encephalitis virus in Asia, currently both Genotype Ⅰ （G1） and Genotype Ⅲ （Ga） strains are circulating in China, while JEV isolates from Fujian belonged to G3. In this report, five clinical JEV strains were isolated from specimens of suspected JE patients in Fujian, 2005-2008. Phylogenetic analysis of partial C/PrM and fullqength g genes revealed these five strains also belonged to G3. Meanwhile, homogeneity analysis indicated that 2005-2008 isolates were closely related to strains from several years ago, rather than to those strains from 1950s. Minor variations were identified at several amino acid residues of the envelope protein, however, none of these mutations was associated with pathogenicity of JEV. These data contribute to continuous tracking of the geographic evolution of JEV over a long period.