麻疹减毒活疫苗S191感染性克隆的构建及鉴定

Construction and identification of infectious clone of S191 virus strain used for the production of live attenuated measles vaccine

目的：构建稳定的麻疹减毒活疫苗 S191感染性克隆。方法采用全基因合成方法获得麻疹减毒活疫苗 S191 cDNA 全长及辅助蛋白 N、P、L 基因片段，分别将该4个基因构建入转录与表达载体 pVAX1后，共转染293T 细胞，通过与 Vero 细胞共培养拯救出麻疹病毒，对拯救获得的病毒用间接免疫荧光法、传代实验及序列测定进行鉴定分析。结果酶切及测序表明除遗传标签（突变碱基2101 C-A）外其基因序列正确，用免疫荧光技术证实其能与麻疹病毒核衣壳蛋白和磷蛋白单克隆抗体产生特异性反应，所拯救病毒感染 Vero 细胞后可致细胞病变效应，传代实验表明病毒可以稳定感染 Vero 细胞。结论成功构建了稳定的麻疹减毒活疫苗 S191感染性克隆，初步建立了用于麻疹病毒研究的反向遗传学方法，为新型疫苗的研发提供参考资料。

Objective To construct a stable infectious clone of S191 virus strain used for the production of live attenuated measles vaccine. Methods Full length cDNA of S191 strain and gene fragments encoding nucleocapsid（N）,phosphoprotein（P）and RNA polymerase（L）were synthesis and respectively cloned into the vector pVAX1. The 293T cells were respectively transfected with the recombinant expression plasmids and co-cultured with Vero cells. The supernatants of cell culture were collected for identifying rescued viruses. The indirect immunofluorescence assay was performed for virus identification. The rescued viruses at different passages in Vero cells and the sequences of the rescued viruses were analyzed. Results Restriction enzyme digestion and sequence analysis showed that the recombinant expression plasmids containing the full length cDNA with an artificially engineered mutation at nucleotide 2101（C-A）and gene frag-ments encoding N,P and L proteins of S191 strain were constructed successfully. The N and P proteins were detected in Vero cells with immunofluorescence assay. A cytopathogenic effect on Vero cells was induced by rescued viruses. Conclusion The stable infectious clones of S191 virus used for the production of live attenuated measles vaccine were rescued successfully. An approach by using reverse genetics technique for S191 strain study was established which could be used for the development of new chimeric vaccines against measles virus.