Toxoplasma gondiiα-amylase deletion mutant is a promising vaccine against acute and chronic toxoplasmosis

Individuals with inhibited immunity may develop lethal toxoplasmosis; thus, a safe and effective vaccine is urged to be developed.Toxoplasma gondii(T. gondii) alpha-amylase (alpha-AMY) is one of the enzymes responsible for starch digestion. In the present study, we first generated a ME49 Delta alpha-amymutant and discovered that loss of alpha-AMYrobustly grewin vitrobut contributed to significant virulence attenuationin vivo. Therefore, we established a mouse model to explore the protective immunity of Delta alpha-amymutant against acute and chronic toxoplasmosis. The results indicated that the survival rates of short-term or long-term immunized mice re-infected with the tachyzoites of multipleT. gondiistrains were nearly 100%. ME49 Delta alpha-amynot only could provide protective immunity against tachyzoites infection but also could resist the infection of tissue cysts. Furthermore, we detected that ME49 Delta alpha-amyvaccination could effectively eliminate the proliferation of parasites in mice and prevent the formation of cysts. The significant increases of Th1-type cytokines, Th2-type cytokines and specific total IgG and IgG subclasses (IgG2a and IgG1) confirmed efficiency of a combination of cellular and humoral immunity against infection. In conclusion, ME49 Delta alpha-amyattenuated strain can produce strong immune responses to provide efficient protection against toxoplasmosis, which signifies that ME49 Delta alpha-amymutant may be a potential vaccine candidate.