ABSTRACT
Toxoplasma gondii is an obligate intracellular protozoan that causes Toxoplasmosis in human and animal. In recent years, significant progress has been made in the identification of vaccine candidates which can induce protective responses. In this study we used complete Rhoptry protein 2 gene of Toxoplasma gondii as a single DNA vaccine and evaluated its immune responses in comparison with control groups. BALB/c mice were immunized intramuscularly with three weaks time interval with pcROP2 [as case group] and pc-DNA3 and PBS [as control groups]. After immunization, we evaluated the immune response using cytokine and antibody measurements. The results of cytokine [IFN-gamma, IL-4] assays showed that mice immunized with pcROP2, elicited stronger Th1-type cellular immune responses than those immunized with empty plasmid, or PBS [high level of IFN-gamma and low-level of IL-4]. Also Anti-T. gondii IgG titres [OD] increased markedly in the pcROP2 group, which was significantly higher than those of control groups [P<0.05]. When challenged with the highly virulent Toxoplasma gondii RH strain, mice immunized with pcROP2 had siginificantly higher survival rates compared to control groups [P<0.05]. This study showed that pc-ROP2 as a single DNA vaccine is effective to prime enhanced and balanced cellular and humeral immunity responses, and relatively improved mice survival time against toxoplasmosis