一株神经外低毒力乙型脑炎病毒株的全基因序列分析

Analysis of the complete genome of a Japanese encephalitis virus strain with low peripheral virulence

目的探究1株新分离的基因Ⅰ型乙脑病毒株的分子生物学特征及其低毒力的分子基础。方法对病毒株扩增,提取其RNA,逆转录PCR后测序,序列与来自世界不同地区不同基因型的野毒株进行同源性比较,并与强毒P3株进行氨基酸位点比对。结果SC04-17在核苷酸和氨基酸序列上,存在与其他基因型毒株不同的特点,与世界各地毒株核苷酸差异率为1.8%～16.5%,氨基酸差异率为0.8%～5.0%;与减毒活疫苗株SA14-14-2的核苷酸、氨基酸同源性分别为88.5%和97.6%,与灭活疫苗株P3核苷酸、氨基酸同源性分别为88.8%和97.9%;与P3强毒株比对,发现72个氨基酸位点差异,分布在全基因的各个区域(E、NS5、NS1和NS3区)。结论SC04-17株的基因序列存在一些独特位点,这些位点的氨基酸变化可能与其低毒力特征有关。

Objective To explore the molecular characteristics of a newly isolated genotype I Japanese encephalitis （JE） virus strain, SC04-17, with low virulence. Methods RNA was extracted from an amplified virus strain and RT- PCR was used to obtain the gene sequence. Homology of nucleotides and amino acids was compared to other JE virus strains isolated from different areas of the world. Comparison to a highly virulent strain （P3） was done to reveal the mo- lecular basis responsible for the strain＇s low virulence. Results The difference between SC04-17 and strains isolated from around the world in nucleotides and amino acids was 1.8%- 16.5% and 0.8%- 5.0%, respectively. Homology with an SA14-14-2 attenuated strain was 88.5% for nucleotides and 97.60% for amino acids. Homology with a P3 vaccine strain was 88.8% for nucleotides and 97.9% for amino acids. There are 72 differences between the two virus strains in a- mino acids located in different regions of the full genome. Conclusion The amino acid substitutions in the E, NS50 NS3, and NS1 regions may contribute to the lower neuroinvasiveness of the SC04-17 strain.