Objective To construct the recombinant plasmid of pcDNA3.1 ( + )/Gpd-Tp92 containing the outer membrane protein Gpd and Tp92 gene of T. pallidum, and observe its immune response in New Zealand white rabbits. Methods Gpd from pcDNA3.1 ( + )/Gpd was subcloned into the recombinant plasmid pcDNA3.1 ( + )/Tp92 by linking reactions to construct pcDNA3.1 ( + )/Gpd-Tp92, and then the recombinant plasmids were transfected into HeLa cells using liposome. After verifying the Gpd-Tp92 antigen fusion genes could be expressed in HeLa cells by imm...