Protective Efficacy of an IST DNA vaccine with a CL264 molecular adjuvant against Toxoplasma gondii in a murine model

Abstract

Abstract Background Toxoplasmosis, caused by the parasite Toxoplasma gondii (T. gondii), is a significant global zoonosis with devastating impacts. Despite its importance, an effective vaccine against toxoplasmosis for humans has not yet been developed. Vaccination remains the most cost-effective approach in combating this disease. Methods In this study, we designed and formulated a novel DNA vaccine encoding the inhibitor of STAT1 transcriptional activity (IST) of T. gondii utilizing the eukaryotic expression vector pEGFP-N1 for the first time. To enhance the immunoprotection of vaccine, we employed CL264, a TLR7 agonist, as a molecular adjuvant. The immunologic efficacy of this newly constructed vaccine was investigated in a murine model. Following intramuscular injection of the vaccine into mice, various indicators were assessed to evaluate the immune response, including antibodies, cytokines, and the proportion of CD4+ and CD8+ T cells. Additionally, two weeks after the third immunization, mice were challenged with highly virulent RH strain tachyzoites of T. gondii, and their survival time was observed. Results The vaccine demonstrated the ability to induce robust humoral and cellular immune responses in the immunized mice. Notably, TgIST-immunized mice exhibited prolonged survival time after T. gondii RH strain infection. Conclusions Our findings collectively demonstrate that the TgIST DNA vaccine elicits a significant immune response and offers partial protection against acute T. gondii infection in mice. These results suggest that TgIST holds potential as a candidate for further development as a DNA vaccine.