我国新分离森林脑炎病毒E基因特征分析

为了解分离自黑龙江省大兴安岭林区全沟硬蜱中的DXAL-5、12、13、16、18,21共6株森林脑炎(TBE)病毒E蛋白基因特征并确定病毒基因型,应用RT-PCR技术对6株病毒E蛋白基因进行体外扩增、克隆、测序.结果发现,6株病毒E蛋白基因的核苷酸序列长均为1 488 bp,推导的氨基酸序列长均为496 aa.与TBE参考毒株E蛋白基因进行比较,这6株病毒与远东亚型同源性最高,其次是西伯利亚亚型,与欧洲亚型同源性最差;在决定亚型特征的氨基酸位点多数属于TBE病毒远东亚型.E蛋白基因推导的氨基酸种系发生树分析表明,6株病毒均在远东亚型分枝内.因此就E蛋白基因而言,DXAL-5、12、13、16、18、21株均属于TBE病毒的远东亚型.新分离毒株与Senzhang株同源性较高,种系发生关系也比较接近,推测疫苗株对新分离毒株仍具有很好的保护作用.但是在E蛋白的A、B和C抗原决定区内,6株病毒均有不同程度的氨基酸改变,这些突变有可能影响E蛋白的功能.

Characteristic Analysis of E Protein Genes of New Strains of Tick-borne Encephalitis Virus Isolated from China

In order to determine the characteristics and genotypes of E protein genes of tick-borne encephalitis (TBE) virus strains DXAL-5, 12,13,16,18, 21 isolated from Ixodes persulcatus in the Northeast of China, cDNA synthesis of E protein genes of the six DXAL strains was performed using RT-PCR, and the E protein genes were cloned and sequenced. The results showed that the nucleotide sequence of E protein gene of the six DXAL strains was 1488 bp in length respectively and the length of predicted protein was 496 aa respectively. Sequence comparison of E protein genes among the six DXAL strains and the reference TBE virus strains showed that the six DXAL strains were more homologous to Far Eastern subtype strains than to Siberian subtype strains or European subtype strains. And the majority of subtype-determing amino acid sites of the six DXAL strains belonged to TBE virus Far Eastern subtype. Phylogenetic analysis of protein E showed that the six DXAL strains were all within the clade containing Far Eastern subtype strains.The new strains had higher identities and closer phylogenetic relationships with Senzhang strain, so we speculate that this vaccine strain still have good protection against the new TBE virus isolates. In the A, B and C antigenic domains of protein E, the six DXAL strains had different degrees of amino acid changes. These mutations were likely to affect the function of E protein..