[Study on construction and immune protective effect of recombinant nucleic acid vaccine of Toxoplasma gondii].
OBJECTIVE
To construct the polyvalent recombinant nucleic acid vaccine of Toxoplasma gondii and measure its protective immune effect.


METHODS
The gene of heat shock protein (HSP70) was amplified by PCR and inserted into the recombinant plasmid of pcDNA3-ROP2-p30 to construct recombinant polyvalent nucleic vaccine (pcDNA3-ROP2-p30-Hsp70). BALB/c mice were immunized with the constructed recombinant nucleic vaccine. CD4+ and CD8+ in the splenic lymphocytes and the lymphocytes in anticoagulant whole blood, the immune indices such as antibodies (IgG, IgM and IgA) and IFN-gamma, TNF, IL-2, IL-4, IL-12 in serum and splenic lymphocytes culture medium were detected, along with the challenge experiment. The protective immune responses that caused by the vaccine was measured by detecting the changes of immune indices of mice and the challenge experiment.


RESULTS
916 bp fragment of HSP70 gene was amplified by PCR. The recombinant polyvalent nucleic vaccine pcDNA3-ROP2-p30-HSP70 that included the whole open reading frame sequence of HSP gene was successfully constructed. The immunization results also showed this polyvalent nucleic vaccine could induce strong cellular and humoral responses by the detection of higher antibody titer in the experimental mice group, the increasing proliferation of CD4+ and CD8+ cells with significant deviations among the groups (F(CD4+) = 45.00, F(CD8+) = 15.01, all P < 0.01) and the apparent up-regulated levels of several cytokines IFN-gamma, IL-2 and IL-12 in serum and cultural supernatant of spleen cells, with more striking effect in serum. As a result of the challenge experiment, the immunized mice showed a longer survival time.


CONCLUSIONS
The recombinant nucleic acid vaccine pcDNA3-ROP2-p30-HSP70 possesses a strong immunogenicity and is able to induce an immune protection.
Shandong Academy of Medical Sciences, Shandong Institute of Parasitic Disease, Jining 272033, China.
Qing-Kuan
QK
Wei
D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood / Q000276:immunology; D016516:CD4-CD8 Ratio; D016207:Cytokines / Q000097:blood / Q000276:immunology; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000276:immunology*; D008565:Membrane Proteins / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D015800:Protozoan Proteins / Q000276:immunology; D016052:Protozoan Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000276:immunology; D014122:Toxoplasma / Q000235:genetics* / Q000276:immunology*; D014123:Toxoplasmosis / Q000276:immunology / Q000517:prevention & control*; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*
D000913:Antibodies, Protozoan; D016207:Cytokines; D018840:HSP70 Heat-Shock Proteins; D008565:Membrane Proteins; D015800:Protozoan Proteins; D016052:Protozoan Vaccines; C090555:ROP 2 protein, Toxoplasma gondii; D019444:Vaccines, DNA