Hbc Particles For Display Vector Cysticercosis Vaccine And Immunological Study

Taenia solium cysticercosis is a common parasitic disease of humans in several countries in Latin America, Africa, and Asia, where it represents a major health and economic problem. As the pig is the mediate host, development of an effective vaccine to be used in pigs is an important method.Several approaches are being used currently towards the development of a T. solium vaccine including vaccines using native and recombinant oncosphere antigens from whole T. solium cysticercus, protein sub-unit vaccines and DNA vaccines. In research of vaccines against parasites, the protective antigen is the most important factor. Epitopes KETc1, KETc12, and GK-1 are three promising candidates for designing a vaccine against T. solium cysticercosis. For convenience, the three epitopes were termed n1, n2, n3, respectively.Many studies have provided evidence that Hepatitis B core antigen particle is used as a vaccine carrier to take foreign epitopes. HBc particle exhibits a remarkable capability to accept mutational intervention and undergo correct folding and self-assembly in all viable prokaryotic and eukaryotic expression systems, and it possesses not only an outstanding ability to induce B cell, T helper (Th) and cytotoxic T cell (CTL) response, but also permits the inserted polypeptides to exhibit the appropriate immunological properties.Based on the knowledge above, we constructed a prokaryotic expressed plasmid pET28a-Ac-3n which encoded a truncated HBc protein (amino acids 1 -149) with two epitopes (n1 and n2) inserted between HBc amino acids 78 and 79, a region located at the tip of the core particle surface spikes, and one epitope (n3) fused to its C-terminus. After IPTG induction, a recombinant protein with expected molecular mass was efficiently expressed and was termed Ac-3n. By SDS-PAGE, the gel was cut for purification. The purified product was subjected to SDS-PAGE and it resulted in a single band. We performed an incomplete SDS-PAGE study whether Ac-3n protein could assemble itself under such conditions. The formation of protein particle was verified by electron microscopy.We used purified Ac-3n protein to inoculate the BALB/c mice. Specific antibody IgG, IgG1 and IgG2a were analyzed. High antigen-specific antibody titers in immunized mice were elicited. And IgG1 and IgG2a were both enhanced, indicating mat specific immune response induced by Ac-3n protein was a mixed Th1 and Th2 type.Cysticercus tissues were used for western blot analysis to determine the specific antibody. Results showed that three different antibodies reacted with different cysticercus tissues, indicating that three epitopes might have induced three antibodies.We also performed dot ELISA to investigate the protection of the selected epitopes. We found the seri of cysticercosis pig and humans didn't react with the Ac-3n protein. We could deduce that the three epitopes we chose might induce protective immune response. We challenged the immunized mice with infectious T.solium eggs and observed the relative protective rate, which was 89% as a result of the challenge test.