口蹄疫病毒NSP 3ABC基因在昆虫细胞中的分泌表达及其活性检测

用设计的特异引物，扩增得到了N-端带有6×His编码序列的口蹄疫病毒完整3ABC基因序列，并将其亚克隆入带有蜂毒溶血肽序列的穿梭质粒pMelBac-B中，构建了重组质粒pMel-3ABC。将该重组质粒与杆状病毒骨架DNA Bac-N-Blue^TM共转染Sf9昆虫细胞，通过噬斑筛选和PCR鉴定，获得了含有目的基因的重组杆状病毒。重组病毒感染Sf9昆虫细胞，采用通过SDS-PAGE和Western blot检测，证明目的基因在昆虫细胞中得到了正确的表达，表达产物分泌至细胞培养上清中，并具有良好的生物活性。表达的目的蛋白经过镍柱亲和层析法纯化后，用间接ELISA方法检测与口蹄疫病毒感染动物血清的反应性，证明表达目的蛋白与感染动物血清有很好的反应性而与正常动物以及免疫动物血清不发生反应。该研究为建立一种更加敏感和特异的口蹄疫病毒感染动物与疫苗免疫动物的鉴别诊断方法奠定了基础。

Secreted Expression of Nonstructural Protein Gene 3ABC of Foot-and-Mouth Disease Virus in Sf9 Cells and Activity Analysis

Entire 3ABC sequence of FMDV containing a 6×his tag coding sequence at the N-terminal was obtained through PCR amplification using a pair of specific primers, subcloned into shuttle plasmid of pMelBac-B with a melittin secretion signal sequence and finally constructed recombinant plasmid of pMel-3ABC. After co-transfected the recombinant plasmid and linearized Bac-N-Blue^TM DNA into Sf9 insect cell under intermediary agent of the Cellfectin^?, the result showed that we have already acquired recombinant baculovirus by screen of plaque assay and identification of PCR. Though the recombinant baculovirus infecting the Sf9 cells again, experiments indicated that 3ABC gene could express in insect cells and the expressed protein was secreted in the supernatant of Sf9 cell culture possessing favourable biological activities detected by adopting two methods of SDS-PAGE and Western blot. The result verified that the protein could respond with sera derived from FMDV infected animals, but have no responsibility with sera derived from health animals and vaccinated animals detected by indirect ELISA using antigen of expressed protein after purification with Ni-NTA his bind resin. Therefore, this study has established a solid foundation for establishing an effective diagnosis method to discriminating the FMDV infected animals from vaccinated animals.