Theoretically, a multi-component vaccine containing more CTL epitopes may elicit better protective immunity against parasite infection than a single antigen due to the enhanced numbers of T. gondii-specific CTLs, thereby leading to elevated production of the antigen-specific cytokine IFN-γ (Jongert et al., 2010; Wang et al., 2019a). The gene discussed is IFNG; the disease is parasitic infectious disease.