从病毒性脑炎患者标本分离的基因I型乙脑病毒全基因组序列特征研究

目的通过现代分子生物学理论与技术测定和分析了从脑炎患者脑脊液标本分离的基因I型乙脑病毒（GZ56株）全基因组序列特征，以了解其致病性的分子基础。方法采用RT．PCR法和核酸序列测定法获得病毒基因组全序列，并利用DNASTAR、ClustalX version2．0．9及MEGAversion4．1等生物学软件分析该乙型脑炎病毒核苷酸序列、氨基酸序列及系统进化等。结果研究结果表明从病毒性脑炎患者脑脊液标本分离的基因I型乙脑病毒（GZ56株）基因组全长为10965nt，编码3432个氨基酸。病毒全基因组分子进化分析显示GZ56株全基因组与国际上第一株从蚊虫分离的基因I型乙脑病毒（M-28株）处于同一进化分支。GZ56株与其他基因I型乙脑病毒核昔酸和氨基酸序列同源性分别为96．2％～98．6％和98．2％～99．7％。病毒E基因与乙脑病毒灭活疫苗株P3相比存在11个氨基酸差异位点，而与乙脑病毒减毒活疫苗株SA14-14-2相比，在E蛋白上存在14个氨基酸差异位点。结论本研究提示，从病毒性脑炎患者标本分离的基因I型乙脑病毒全基因组未见明显变化，从基因组水平可以推测该病毒可以被现行的乙脑疫苗所保护。

Molecular characteristics of the genome of G I of Japanese encephalitis virus isolated from the specimen collected from viral encephalitis case for the first time

Objective To investigate the molecular basis of pathogenicity of Japanese encephalitis virus （JEV） by sequencing of complete nucleotide sequence and analyze the characteristics of full-length genome of genotype I Japanese encephalitis virus strains （GZ56） which was isolated from the first cerebrospinal fluid （CSF） of Japanese encephalitis patients. Methods The complete nucleotide sequence was obtained by RT-PCR and sequencing was performed directly. Bioinformaties was used to analyze the nucleic acid data, deduced amino acid sequence and phylogenetie trees. Results The result of sequence analysis showed that the genome of GZ56 strains had 10 965 nucleotides, which coded for a 3432-amino acid polyprotein. Phyolngenetic analysis based on full-length genome showed that GZ56 strains and M-28 strains which were the first isolated from mosquitoes in Yunnan in 1977 were in the same evolutionary branch. GZ56 strains belongs to genotype I of Japanese encephalitis virus, the homology of genome ranged from 96.2% to 98.6% in nueleotide and from 98.2% to 99.7% in amino acid sequences respectively when compared with selected genotype I of JEV strains in GenBank. There were 11 amino acid divergences in E protein when compared with the JEV inactivated P3 strain but they are not the key virulence sites. However, there were 14 amino acid divergences in E protein when compared with the JEV live attenuated vaccine SA14-14-2 strain and 8 amino acid divergences were the key virulence sites. Conclusion This study indicated that the full length of genome GZ56 strains had no ignificant change. It can be hypothesized from genomic level that the currently available JEV vaccines（ inactivated and live attenuated） can protect against GZ56 strains infection,meanwhile,the JEV live attenuated vaccine（SA14-14-2）