Vaccinia virus expressing MIC8 and AMA1 provides protection against Toxoplasma gondii ME49 infection.

Toxoplasma gondii is an intracellular protozoan parasite capable of causing chronic infection by forming persistent cysts in the brain. Despite its global burden, no approved vaccine exists. Virus-like particle vaccines expressing microneme protein 8 (MIC8) or apical membrane antigen 1 (AMA1) of T. gondii have previously shown efficacy. In this study, we generated recombinant vaccinia viruses (rVVs) expressing MIC8 and AMA1 and evaluated their efficacy against T. gondii ME49 infection. BALB/c mice were intramuscularly immunized with a combination of MIC8 and AMA1 rVVs and challenged orally with T. gondii ME49. Immunization with MIC8+AMA1 rVVs produced a significant increase in T. gondii-specific IgG. Splenocyte analysis revealed robust activation of CD4+ and CD8+ T cells, as well as expansion of memory B cells. The immunized group exhibited an 89.6% reduction in brain cyst count, with significantly improved survival compared to the control group. These findings demonstrate that combining the antigens MIC8 and AMA1 using a vaccinia virus platform can effectively promote both humoral and cellular immunity, supporting its potential as a vaccine strategy against T. gondii ME49.