FIG 3.

P. cynomolgi drug assays with selected malaria box compounds. (A) Structure formulas of KAE609, KAF156, KAI407, and primaquine. (B) Three-point 10-fold dilution series (0.1, 1, and 10 μM) on P. cynomolgi liver stage cultures. The percentage of untreated control is shown as a function of the compound concentration. Differential counting of schizonts and hypnozoite forms was performed based on size and number of parasite nuclei. The results of one representative assay are shown; assays were performed at least twice. KAE609 was not active against liver stage parasites and was therefore not taken forward for IC₅₀ determination. (C) IC₅₀ determination for KAF156, KAI407, and primaquine. Drugs were tested in a 2-fold dilution series. The percentage of untreated control is shown as a function of the compound concentration. Differential counting of schizonts and hypnozoite forms was performed based on size and number of parasite nuclei. IC₅₀s were calculated based on fitted curves (nonlinear fit). The results of one representative assay are shown, and at least two independent assays were performed. The activity of KAF156 is limited to schizonts, while KAI407 and primaquine also kill hypnozoite forms. The error bars indicate standard deviations.