水泡性口炎病毒核蛋白基因的表达及初步应用

Expressing of N Gene Encoding Nucleocapsid Protein of Vesicular Stomatitis Virus and Elementary Application in ELISA

将水泡性口炎病毒编码群特异性抗原的N基因片段克隆至pMD18 T克隆载体质粒中 ,构建N基因克隆重组质粒 ,进行核苷酸序列分析。然后亚克隆插入pBAD ThioTOPO表达载体 ,经PCR限制性内切酶分析、测序鉴定 ,筛选获得N基因正向插入、有正确读码框的阳性克隆 ,成功构建了水泡性口炎病毒N基因重组表达载体。经L Arabinose诱导表达 ,可稳定、高效地表达N蛋白抗原。SDS PAGE、Westernblotting及间接ELISA试验结果表明 ,表达蛋白为融合蛋白 ,质量约 6 3 5kD ,其表达产量约占菌体总蛋白的 16 % ,相当于 92mg L。融合蛋白中含有水泡性口炎病毒群特异性的核蛋白抗原 ,应用表达的VSV核蛋白抗原建立了酶联免疫吸附试验 ,通过对 186份山羊、豚鼠实验动物人工感染VSV的血清样品和参考血清样品的检测 ,并与微量血清中和试验进行了比较 ,结果表明 :以表达的VSV核蛋白为包被抗原的酶联免疫吸附试验是一种特异性强、敏感性高、快速、简单、安全的检测方法 ,抗原制备成本低。

The gene encoding the nucleocapsid (N) protein of vesicular stomatitis virus(VSV-NJ) was subcloned from pMD-VN5, and inserted into pBAD/Thio TOPO vector. The recombinant plasmid was identified by restriction analysis and PCR. It was sequenced to confirm the correct sequences and the correct junctional orientations of the inserted N gene. The results of SDS-PAGE and Western immunoblotting revealed that the N protein was expressed in Escherichia coli LGM194 in a high level and the recombinant fusion protein, which contained a N-terminal HP-Thioredoxin and a C-terminal polyhistidine tag. It had a molecular mass of approximately 63.5 kD and immunologically reactive activity. The recombinant protein was characterized and tested in an enzyme-linked immunosorbent assay (ELISA) format for potential application in the serodiagnosis of vesicular stomatitis using 186 serum samples from experimentally infected goats and guinea-pigs with VSV-NJ and VSV-IN, and from field origin and reference serum samples. The sensitivity and specificity of the ELISA were compared with those of the standard microtiter serum neutralization (MTSN) tests. The ELISA and MTSN test results were highly correlated for detection of VSV antibodies. The ELISA was as sensitive as the SN assay in detecting positive serum to VSV. The correlation between SN titers and ELISA titers was statistically significant. These data suggest that the recombinant fusion N protein of VSV could be used as a recombinant test antigen for the serodiagnosis of vesicular stomatitis. The ELISA based on the reconmbinant nucleocapsid protein may offer the best combination of rapidity, sensitivity, simplicity, economy, and laboratory biosafety of any of the methods yet developed for VSV serodiagnosis. This study lay on foundation for the development of the diagnosis methods in serology for VSV.