Objective To study the immunological characteristics induced in C57BL/6 mice by nucleic acid vaccine harboring the gene encoding glyceraldehyde-3-phosphate dehydrogenase（GAPDH）of Schistosoma japonicum. Methods The gene encoding GAPDH of S. japonicum from screening of cDNA library was amplified using universal primer T3 promoter and T7 promoter, the PCR product was cloned into the T-A vector pT-Adv. GAPDH-pT-Adv and eukaryotic expression vector pcDNA3 were digested by restriction endonucleases HindⅢ and XhoⅠ, and the nucleic acid vaccine harboring the gene encoding GAPDH was then constructed by ligating the digested products. C57BL/6 mice were immunized using the purified pcDNA3-SjGAPDH. The expression of GAPDH in local muscle in mice was examined by immunofluorescence assay. The specific characteristics induced by pcDNA3-SjGAPDH were analyzed using SDS-PAGE, Western blotting, and ELISA respectively. Results Light green fluorescence was observed in local muscle cell under the fluoroscope 24 and 48 hours after immunization, which indicated the expression of GAPDH. The recombinant plasmid induced specific anti-GAPDH IgG, predominantly IgG2a, IgG2b and IgG3. Cytokines IFN-γ, IL-2 but IL-4 were detected in C57BL/6 mice vaccinated with the vaccine. Conclusion The DNA vaccine, pcDNA3-SjGAPDH induces Th1 type immune response in mice.
