DNA vaccine against Taenia solium cysticercosis expressed as a modified hepatitis B virus core particle containing three epitopes shared by Taenia crassiceps and Taenia solium.

Many studies have provided evidence that the hepatitis B core antigen particle is useful as a vaccine carrier for foreign epitopes. Epitopes KETc1, KETc12, and GK-1 are three promising candidates for designing a vaccine against Taenia solium cysticercosis. In the present study, epitopes KETc1 and KETc12 were inserted into the immunodominant loop of the truncated HBc149, and epitope GK-1 was fused to its C-terminus. The fused protein deltaC-3n was expressed and purified successfully. The polymeric character was tested by SDS-PAGE. After inoculation of BALB/c mice with deltaC-3n, antibody titers were assayed by ELISA, and the antibody specification was analyzed by Western blot. Dot ELISA was performed to verify the protection of the three epitopes. Results showed that the purified polymeric protein was formed, high antibody titers were induced in immunized mice and three antibodies different in molecular weight were induced, serum specific antibody recognized the native peptide localized mainly in cyst wall cells, and there was no specific antibody toward the three epitopes in sera of infected pig and humans. All these revealed that the protein deltaC-3n was a potential candidate for vaccine against cysticercosis. So the deltaC-3n sequence and the signal peptide sequence of IL-2 were cloned to a vector pVAX3.0 to construct pVAX-S-deltaC-3n. Pigs were immunized with pVAX-S-deltaC-3n. Two weeks after the immunization booster, pigs were introduced to infectious T. solium eggs. The relative protective rate induced in pigs immunized with the DNA vaccine pVAX-S-deltaC-3n was 83%.