Abstract: 　AIM: To construct the eukaryotic expression system with pcDNA3-PfCSP/HeLa for CSP gene of \{Plasmodium\} falciparum, and to observe the immune responses in BALB/c mice induced by the expressed proteins. \{METHODS\}: The recombinant plasmid pcDNA3-PfCSP was transformed into mammalian cell line of human HeLa cells. The expressed protein was isolated and analyzed by SDS-PAGE and used for immunization of BALB/c mice by subcutaneous, intravenous or intraperitoneal administration, respectively. ELISA, Western blotting, T lymphocyte proliferation test, natural killer cell activity and CD4\++ and CD8\++ T cells detection were used for observation of the level of humoral and cellular immune responses. RESULTS: Immune sera strongly reacted with the expressed protein. The titer of the antibodies was up to 1∶6 400 by ELISA. Western blotting analysis revealed a specific band at 38.3 kDa. The specific proliferative response with immunized BALB/c mice spleen cells was remarkablely higher than that with control ones. The ratio of CD4\++ and CD8\++ T cells and the NK cell activity were significantly higher in the immunization group than that in the control groups. CONCLUSION: The humoral and cell-mediated immune responses and elevated NKC activity to expressed products with the eukaryotic expression system can specifically be detected in BALB/c mice to generate, indicating that the expressed protein could enhance immune activity in mice. \;

Key words: Plasmodium falciparum, circumsporozoite protein, HeLa cell, expressed product, immune response