Double-stranded RNA specific to adenosine kinase and hypoxanthine-xanthine-guanine-phosphoribosyltransferase retards growth of Toxoplasma gondii.

Adenosine kinase (AK) and hypoxanthine-xanthine-guanine phosphoribosyltransferase (HXGPRT) are the two key enzymes involved in the purine salvage pathway in Toxoplasma gondii. In this study, we targeted the genes encoding AK and HXGPRT in T. gondii for inhibition by exposing the parasites to the corresponding double stranded RNAs (dsRNAs). We report here that dsRNAs targeting both AK and HXGPRT were effective at eliciting suppression of the corresponding gene in cultured tachyzoites. When both of these genes were targeted by dsRNA simultaneously, the average doubling for the dsRNA-treated parasites at 24 h, 30 h, and 42 h was 1.85, 2.62, and 4.27, respectively, significantly lower than that of mock-treated parasites. The data show that transfection of dsRNAs into cells can efficiently regulate gene expression in T. gondii. Application of dsRNA to disrupt gene expression in T. gondii would be useful for elucidating gene function as a step towards the development of therapeutic reagents.