BackgroundToxoplasma gondiiis an obligate intracellular apicomplexan parasite and is responsible for zoonotic toxoplasmosis. It is essential to develop an effective anti-T. gondiivaccine for the control of toxoplasmosis, and this study is to explore the immunoprotective effects of a live attenuated vaccine in mice and cats.MethodsFirst, theompdcanduprtgenes ofT. gondiiwere deleted through the CRISPR-Cas9 system. Then, the intracellular proliferation and virulence of this mutant strain were evaluated. Subsequently, the immune responses induced by this mutant in mice and cats were detected, including antibody titers, cytokine levels, and subsets of T lymphocytes. Finally, the immunoprotective effects were evaluated by challenge with tachyzoites of different strains in mice or cysts of the ME49 strain in cats. Furthermore, to discover the effective immune element against toxoplasmosis, passive immunizations were carried out. GraphPad Prism software was used to conduct the log-rank (Mantel–Cox) test, Student’sttest and one-way ANOVA.ResultsThe RHΔompdcΔuprtwere constructed by the CRISPR-Cas9 system. Compared with the wild-type strain, the mutant notably reduced proliferation (P< 0.05). In addition, the mutant exhibited virulence attenuation in both murine (BALB/c and BALB/c-nu) and cat models. Notably, limited pathological changes were found in tissues from RHΔompdcΔuprt-injected mice. Furthermore, compared with nonimmunized group, high levels of IgG (IgG1 and IgG2a) antibodies and cytokines (IFN-γ, IL-4, IL-10, IL-2 and IL-12) in mice were detected by the mutant (P< 0.05). Remarkably, all RHΔompdcΔuprt-vaccinated mice survived a lethal challenge with RHΔku80and ME49 and WH6 strains. The immunized sera and splenocytes, especially CD8+T cells, could significantly extend (P< 0.05) the survival time of mice challenged with the RHΔku80strain compared with naïve mice. In addition, compared with nonimmunized cats, cats immunized with the mutant produced high levels of antibodies and cytokines (P< 0.05), and notably decreased the shedding numbers of oocysts in feces (95.3%).ConclusionsThe avirulent RHΔompdcΔuprtstrain can provide strong anti-T. gondiiimmune responses, and is a promising candidate for developing a safe and effective live attenuated vaccine.Graphical abstractSupplementary InformationThe online version contains supplementary material available at 10.1186/s40249-023-01109-9.