赖型钩端螺旋体溶血素基因HlyX的真核表达及基因免疫

目的 在哺乳动物细胞中表达含有赖型钩端螺旋体溶血素基因HlyX的重组质粒,并检测其作为DNA疫苗诱导小鼠体液免疫应答的效果.方法 以赖型钩端螺旋体全基因组为模板,PCR扩增出目的基因HlyX,以质粒pcDNA3.1为载体,双酶切构建重组质粒,转化大肠杆菌DH5α,双酶切、PCR及测序鉴定重组质粒.将构建成功的重组质粒转染COS-7细胞,通过RT-PCR、Western blot鉴定目的基因的表达.将重组质粒免疫BALB/c小鼠,每两周1次,共3次,ELISA法检测小鼠的体液免疫应答水平.结果 扩增出全长约1100 bp的HlyX基因,重组质粒经双酶切、PCR及测序鉴定表明重组质粒构建成功.RT-PCR检测显示重组质粒转染组能扩增出约1100 bp的目的基因片段,Western blot分析可见在相对分子质量(Mr)40×103左右出现特异性的目的条带.DNA免疫后诱导小鼠产生了较高的抗体水平(1∶6561～1∶19 683).结论 赖型钩端螺旋体溶血素基因HlyX真核表达质粒能够诱导小鼠产生高滴度的特异性抗体,为其作为钩体DNA疫苗的研究和开发奠定了基础.

Eukaryotic expression and DNA immunization of hemolysin HlyX gene from Leptospira serovar Lai

Objective To study on the expression of the eukaryotic recombinant vector carrying HlyX gene of Leptospira serovar Lai in mammalian cell and explore the humoral immune response in BALB/c mice immunized with the recombinant plasmid. Methods The HlyX gene was amplified from Leptospira serovar Lai genomic DNA by PCR and inserted into pcDNA3.1 vector. After transformed into E. coli DH5α,the recombinant plasmid was assayed for identification by PCR analysis,restriction nuclease enzyme digestion and sequencing. The recombinant plasmid was transfected into COS-7 cells,then RT-PCR and Western blot were performed to test the expression of the target gene. The recombinant plasmid was injected intramuscularly into BALB/c mice for three times at intervals of two weeks,and the antibody titer was measured by ELISA. Results PCR showed the full length HlyX gene was about 1100 bp. PCR analysis,restriction nuclease enzyme digestion and sequencing indicated the recombinant vector was constructed successfully. After the plasmid Was transfected into COS-7 cells,a fragment about 1100 bp was found by RT-PCR and a specific band relative molecular mass(Mr)about 40×103,which was consistent with the expected size of the target proteins was showed by Western blot. ELISA showed the antibody titer in BALB/c mice immunized by the HlyX gene of Leptospira serovar Lai can elicit high-titer antibody in BALB/c mice,which has laid the foundation for the application of the DNA vaccine.