Immune responses to the expressed products of the CSP antigen gene of plasmodium falciparum southern China isolate FCC1/HN in Hela cell.
OBJECTIVE
To construct a eukaryotic expression system with pcDNA3-PfCSP/Hela for the Circumsporozoite protein (CSP) gene of Plasmodium falciparum (P. falciparum), to observe the immune responses in BALB/c mice induced by the expressed proteins.


METHODS
The recombinant plasmid pcDNA3-PfCSP was transformed into the Hela cell line. The expressed protein was isolated and analyzed by using SDS-PAGE and used for immunization of BALB/c mice by subcutaneous, intravenous, and intraperitoneal administration. Enzyme-linked immunosorbent assay (ELISA), Dot-ELISA, Western blot, T lymphocyte proliferation test, natural killer cell (NKC) activity assay, and CD4+ and CD8+ T cell detection were used for observation of humoral and cellular immune responses.


RESULTS
Immune sera strongly reacted with the expressed protein, antibody titer was up to 1:6400 as detected by ELISA. Western blot analysis revealed a specific band at 38.3 Kda. When the spleen cells of normal and immunized BALB/c mice were specifically stimulated with expressed protein, the optical densities were 0.12 +/- 0.03 and 0.34 +/- 0.04, respectively. The latter were significantly higher than the former (P < 0.01). We used the MTT colorimetric assay to measure NKC activity of mice spleen. The results showed that the NKC activity of immunized BALB/c mice was remarkably higher than that of the controls (P < 0.05). CD4+ and CD8+ T cells were detected by using monoclonal antibody immunofluorescence methods. The results showed that the percentage of CD4+ and CD8+ T cells of immunized group were significantly higher than that of control group (P < 0.05).


CONCLUSIONS
The humoral and cell-mediated immune responses and elevated NKC activity to products made with a eukaryotic expression system could be specifically detected in BALB/c mice. These findings indicate that the expressed protein could enhance the immune function in mice.
Fang
Z
Z
Department of Parasitology, Nantong Medical College, Nantong 226001, China.
Yu
X
X
Liu
Y
Y
Luo
S
S
D000818:Animals; D016054:DNA, Protozoan / Q000276:immunology*; D006367:HeLa Cells / Q000469:parasitology; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D010963:Plasmodium falciparum / Q000235:genetics*; D015800:Protozoan Proteins / Q000235:genetics*; D014611:Vaccination; D019444:Vaccines, DNA / Q000276:immunology*
D016054:DNA, Protozoan; D015800:Protozoan Proteins; D019444:Vaccines, DNA; C041595:circumsporozoite protein, Protozoan