Toxoplasma gondii α‐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) α‐amylase (α‐AMY) is one of the enzymes responsible for starch digestion. In the present study, we first generated a ME49Δα‐amy mutant and discovered that loss of α‐AMY robustly grew in vitro but contributed to significant virulence attenuation in vivo. Therefore, we established a mouse model to explore the protective immunity of Δα‐amy mutant 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 multiple T. gondii strains were nearly 100%. ME49Δα‐amy not only could provide protective immunity against tachyzoites infection but also could resist the infection of tissue cysts. Furthermore, we detected that ME49Δα‐amy vaccination 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, ME49Δα‐amy attenuated strain can produce strong immune responses to provide efficient protection against toxoplasmosis, which signifies that ME49Δα‐amy mutant may be a potential vaccine candidate.