低神经外毒力乙脑病毒M47株的分子生物学特征

Molecular biological characteristics of Japanese encephalitis virus M47strain with low neuroinvasiveness

目的探究低神经毒力乙脑病毒M47株的分子生物学特征,以期找出其低毒力的分子基础。方法采用RTPCR法扩增M47株病毒全长基因片段,测定其序列,并与GenBank中19株代表性乙脑病毒株全基因序列进行核苷酸和氨基酸比对分析。结果 M47株属于基因Ⅲ型,与GenBank中19株代表性乙脑病毒株核苷酸序列同源性为79.4%-99.6%,氨基酸序列同源性为91.3%-99.6%;氨基酸序列比对发现,该毒株存在一个独特的氨基酸位点改变E-29（S-R）。结论 M47株独特的氨基酸位点改变E-29（S-R）可能是导致其低神经外毒力的原因。

Objective To investigate the molecular biological characteristics Japanese encephalitis virus（JEV） M47 strain so as to search the molecular basis of its low neuroinvasiveness.Methods Full-length gene fragment of M47 strain was amplified by RT-PCR and sequenced,of which the nucleotide and amino acid sequences were compared with those of19 representative JEV strains in GenBank.Results M47 strain belonged to genotype Ⅲ,of which the homologies of nucleotide and amino acid sequences to the 19 JEV strains were 79.4% - 99.6% and 91.3% - 99.6% respectively.One unique amino acid residue at site E-29（S-R）was found in envelope protein through comparison of complete genome of M47 with those of other JEV strains.Conclusion The unique amino acid change at site E-29（S-R） may be responsible for the low neuroinvasiveness of JEV M47 strain.