| Summary: | 碩士 === 中國醫藥學院 === 醫學研究所 === 90 === In our country, Japanese encephalitis virus (JEV)is one of statutory infectious disease, JEV is transmitted to humans by mosquitoes and causes an acute infection of the central nervous system and encephalitis. Because it infects both of human and animals, it is important to research for JEV.
In our study, we cloned and sequenced the full length genome of the JE virus YL strain first. The cDNA sequence of YL strain genome encompasses 10,977 nucleotides is completed, and has an open reading frame which could translate into a polyprotein with 3,432 amino acids, GenBank accession number is AF486638. Nucleotide sequence (YL strain ) compared with other sequenced JE strains showed a homology range from 89.03(K94p05) to 99. 41%( JaGAr01). Amino acid sequence YL compared with other JE strains showd a homology range from 97.52%( K94p05 ) to 99.27% ( JaGAr0 1 ) . Predicted sequence for the 5` noncoding regions of All JEV genomes is conserved and the secondary structure conformation 3` noncoding regions of YL is similar to JaGAr01.YL reveals the highest nucleotide and amino acid homology with JaGAr01. The part of envelope amino acid, determinant of neurovirulence and nuroinvasiveness, is different to JaGAr01, but more similar for JEV HVI strain.
The JEV envelope protein ( E )is the most critical antigen in providing protective immunity, and appears to be an important determinant of neurovirulence as well as neuroinvasiveness. In our study, we made a comparison of amino acids sequence among JE virus strains. The region possessed RGG( 387-389 )amino acid sequence instead of RGD tripeptide, which had been suggested to be involved in the binding with putative receptor. Another amino acid E-138 was replaced with K-138, may also cause CNS receptor binding attenuation and loss neurovirulence. The YL strain possed RGG(387-389) and E-138 in the region of E protein. So, we expect the research will provide insight into the molecular basis of YL and the result reveals that the YL strain is referred as a live attenuated strain.
Furthmore, we success to express a great quantity of envelope protein in E. coli., this recombinat E protein possed properties of antigen and hemagglutinin. We hope the research could provide the application of develop JEV recombinant vaccines and diagnosis kit in the furture.
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