FIG 1.
The piperazine-based Malaria Box compound MMV665917 is a selective inhibitor of Cryptosporidium growth in vitro. (A) Structure of MMV665917 showing a piperazine linker connecting the indicated R and R′ groups. (B) Dose-response curve showing inhibition of C. parvum growth inside HCT-8 cells after 48 h of incubation. Parasite numbers were normalized to those with DMSO, the vehicle control. Each data point represents the mean from 3 biological replicates, with 4 technical replicates per experiment. Error bars indicate standard deviations. (C) Effect of MMV665917 on the proliferation of host HCT-8 cells as assessed by a CellTiter AQueous assay (Promega). Data are means and standard deviations combined from 2 biological replicates with 4 technical replicates each. (D) MMV665917 activity against C. hominis TU502 and three different bovine field isolates of C. parvum. Means and standard deviations from 2 independent experiments, with 4 technical replicates per experiment, are shown, except for C. hominis TU502, where the mean from 3 replicates of 1 biological experiment is shown. (E) Preliminary structure-activity relationship studies using commercially available variants on the R group, demonstrating a preference for aryl urea (D-28) over carboxamides (D-46, D-44), oxyacetamides (D-41), and sulfonamides (D-23, D-79) (also Fig. S2 and Table S2 in the supplemental material).