梅毒螺旋体外膜蛋白Gpd基因的克隆、表达及其免疫活性研究

利用PCR技术从Tp Nichols株基因组模板中扩增梅毒螺旋体(Treponema pallidum,Tp)外膜蛋白Gpd基因,定向克隆构建真核表达重组体pcDNA3.1( )-Gpd,免疫印迹和免疫组化技术检测pcDNA3.1( )-Gpd在HeLa细胞中的表达;同时将真核表达重组体pcDNA3.1( )-Gpd免疫新西兰兔,检测其在兔体内的免疫应答效果。免疫印迹和免疫组化鉴定均显示重组体在HeLa细胞中能有效表达一个41kD的Gpd融合蛋白。新西兰兔接种核酸疫苗后,能产生特异性抗体,第3次免疫后2周抗体最高滴度可达1∶1024,免疫后兔脾细胞受Gpd蛋白刺激有明显增殖反应。所诱导的抗体水平和脾淋巴细胞增殖情况均显著高于空质粒对照组和空白对照组(p<0.05)。Tp真核表达重组体pcDNA3.1( )-Gpd的成功构建及能刺激新西兰兔产生较强特异的免疫应答,为Gpd蛋白生物学功能及梅毒DNA疫苗的深入研究奠定了一定的实验基础。

Cloning and expression of outer membrane protein gene Gpd from Treponema pallidum and preliminary studies on its immunogenicity in rabbits

To construct the recombinant plasmid of Eukaryotic expression containing Gpd gene from Treponema Pallidum and study its immunogenicity in New Zealand White rabbits. Gpd gene was amplified from the genomic DNA of T.pallidum and cloned into appropriate site of pcDNA3.1( ) vector. After verified that the Gpd antigen gene could be expressed in HeLa cells by Western blot and immunocytochemistry, recombinant plasmids pcDNA3.1( )-Gpd, control plasmid pcDNA3.1( ) or PBS buffer were administered in three groups of New Zeal and White rabbits.Booster immunizations were employed at 2-week interval for three times. ELISA was used for the quantitative detection of the specific antibody in the sera of rabbits. The proliferation response of spleen cells was detected by MTT assay. The results of the Western blot and immunocytochemistry showed that Gpd gene constructed in pcDNA3.1( ) vector could express a fusion protein with a calculated molecular mass of 41kD in HeLa cells and react with positive blood serum from syphilis patients. The significant specific antibody IgG titers were observed and the highest titer was 1:1024 in rabbits after three times with pcDNA3.1( )-Gpd. The proliferation response of spleen cells were significantly higher than that of rabbits injected with pcDNA3.1( )(p<0.05).All above results establish a solid basis for future studying the biological activities of Gpd and benefit the development of the Syphilis DNA vaccine.