Induction of FAS II Metabolic Disorders to Cause Delayed Death of Toxoplasma gondii.

The exact mechanism of delayed death of Toxoplasma gondii is not known. FAS II synthesis in the apicoplast of T. gondii is essential for the survival of Toxoplasma gondii, while β-hydroxyacylacyl carrier protein dehydratase (FabZ) is indispensable for fatty acid synthesis. The present study investigated the relationship between the delayed death of T. gondii by inducing metabolic disorders due to suppression the expression of FabZ. A tetracycline-induced knockout vector inserted with T. gondii fabZ gene was constructed, and transfected into T. gondii TATi strain by electroporation. The stable mutants with tetracycline-induced knockout were selected, expression of FabZ was suppressed by using anhydrotetracycline (ATc), and FAS II deficient tachyzoites were prepared. The Western blot and qPCR results revealed that proliferation of FAS II deficient tachyzoites was not significantly different compared to the normal tachyzoites at 24 h and 48 h; however, after 72 h, the number of T. gondii tachyzoites in the ATc treated group was significantly (p < 0.05) less than that of non-treated group, indicating the delayed death of T. gondii caused by the loss of apicoplast and decrease in the expression of FabZ, which inhibited the FAS II metabolism. The results of this study can be used for prevention of toxoplasmosis by inducing delayed death of T. gondii.