Adaptation of the [ 3 H]Hypoxanthine Uptake Assay for In Vitro -Cultured Plasmodium knowlesi Malaria Parasites

The zoonotic malaria parasite Plasmodium knowlesi has recently been established in continuous in vitro culture. Here, the Plasmodium falciparum [(3)H]hypoxanthine uptake assay was adapted for P. knowlesi and used to determine the sensitivity of this parasite to chloroquine, cycloguanil, and clindamycin. The data demonstrate that P. knowlesi is sensitive to all drugs, with 50% inhibitory concentrations (IC50s) consistent with those obtained with P. falciparum This assay provides a platform to use P. knowlesi in vitro for drug discovery.