CD4 and cyst: The vaccine immunization activated Th1-type immune responses, with significantly higher IFN-γ, IL-2, and specific antibody IgG levels, as well as higher proportions of CD4+ and CD8+ cells compared with those in the controls, and significantly extended the survival time of mice that were acutely infected with T. gondii, as well as decreased the cyst burden in mice with chronic infection [33].