We report on the development of a new SYBR Green I-based plate assay for analyzing the activities of antimalarial drugs against intraerythrocytic Plasmodium falciparum . This assay is considerably faster, less labor-intensive, and less expensive than conventional radiotracer (e.g., [ ³ H]hypoxanthine and [ ³ H]ethanolamine)-based assays or P. falciparum lactate dehydrogenase activity-based assays. The assay significantly improves the pace at which antimalarial drug discovery efforts may proceed.

Drug resistance in Plasmodium parasites is a constant threat. Novel therapeutics, especially new drug combinations, must be identified at a faster rate. In response to the urgent need for new antimalarial drug combinations we screened a large collection of approved and investigational drugs, tested 13,910 drug pairs and identified many promising antimalarial drug combinations. The activity of known antimalarial drug regimens was confirmed and a myriad of new classes of positively interacting drug pairings were discovered. Network and clustering analyses reinforced established mechanistic relationships for known drug combinations and identified several novel mechanistic hypotheses. From eleven screens comprising >4,600 combinations per parasite strain (including duplicates) we further investigated interactions between approved antimalarials, calcium homeostasis modulators and inhibitors of phosphatidylinositide 3-kinases (PI3K) and the mammalian target of rapamycin (mTOR). These studies highlight important targets and pathways and provide promising leads for clinically actionable antimalarial therapy.