To evaluate the immunogenicity and immunoprotective effects of a tRNA thiouridylase TgMnmA deletion strain of Toxoplasma gondii(T.gondii)on ICR mice,we constructed a mouse model immunized with RH△MnmA.Mice were immunized with 10 RH△MnmA tachyzoites by in-traperitoneal injection.After 30 d,indirect ELISA was used to detect the specific IgG antibody and its subtypes of immunized mice.Spleen lymphocyte suspension was prepared,and the splenic lym-phocyte subsets were analyzed by flow cytometry.Moreover,the relative expression level of cyto-kine mRNA was detected by real-time fluorescence quantitative PCR.After 30 d of immunization,mice were intraperitoneally inoculated with RH△ku80 tachyzoites.At 5 d post infection,the para-site load in the ascites,heart,liver and brain of mice was measured,and the survival of mice within 30 d after infection was observed and recorded.The results showed that compared with the control PBS group,RH△MnmA immunized group produced higher level of IgG and IgG2a antibodies,higher mRNA relative expression level of cytokines IL-2,IL-4,IL-6,IL-10,IL-12 and IFN-γ,and the number of CD4+and CD8a+in spleen lymphocytes also increased significantly.Mean-while,for the attack of RH△ku80 strain,the immune group can effectively reduce the parasite load in the ascites and some tissues,inhibit the reproduction of parasites In vivo,and significantly improve the survival rate of mice.The results of this study showed that the TgMnmA deletion strain of T.gondii can induce strong humoral and cellular immune responses in mice,and provide good immune protection against the infection of RHΔku80 strain,which has the potential to be-come a potentially promising live attenuated vaccine candidate against T.gondii.

To evaluate the immunogenicity and immunoprotective effects of a tRNA thiouridylase TgMnmA deletion strain of Toxoplasma gondii(T.gondii)on ICR mice,we constructed a mouse model immunized with RH△MnmA.Mice were immunized with 10 RH△MnmA tachyzoites by in-traperitoneal injection.After 30 d,indirect ELISA was used to detect the specific IgG antibody and its subtypes of immunized mice.Spleen lymphocyte suspension was prepared,and the splenic lym-phocyte subsets were analyzed by flow cytometry.Moreover,the relative expression level of cyto-kine mRNA was detected by real-time fluorescence quantitative PCR.After 30 d of immunization,mice were intraperitoneally inoculated with RH△ku80 tachyzoites.At 5 d post infection,the para-site load in the ascites,heart,liver and brain of mice was measured,and the survival of mice within 30 d after infection was observed and recorded.The results showed that compared with the control PBS group,RH△MnmA immunized group produced higher level of IgG and IgG2a antibodies,higher mRNA relative expression level of cytokines IL-2,IL-4,IL-6,IL-10,IL-12 and IFN-γ,and the number of CD4+and CD8a+in spleen lymphocytes also increased significantly.Mean-while,for the attack of RH△ku80 strain,the immune group can effectively reduce the parasite load in the ascites and some tissues,inhibit the reproduction of parasites In vivo,and significantly improve the survival rate of mice.The results of this study showed that the TgMnmA deletion strain of T.gondii can induce strong humoral and cellular immune responses in mice,and provide good immune protection against the infection of RHΔku80 strain,which has the potential to be-come a potentially promising live attenuated vaccine candidate against T.gondii.