Fig. 3

AN7973 acts rapidly to eliminate Cryptosporidium in vitro. Time-kill curves showing in vitro effects of nitazoxanide (NTZ) or AN7973 on C. parvum (Bunch Grass Farms Iowa isolate) following compound exposure. NTZ or AN7973 were added at varying concentrations ~24 h after infecting HCT-8 cell monolayers, and then parasites were stained and enumerated by high-content microscopy at the indicated time points. Different compound concentrations are indicated in all graphs as follows: open blue squares and blue lines (DMSO control); solid black circles and black lines (EC₅₀); solid black squares and black lines (EC₉₀); open gray triangles and gray lines (3 × EC₉₀); solid red triangles and red lines (6 × EC₉₀); solid green hexagons and green lines (9 × EC₉₀); and open cyan circles and lines (12 × EC₉₀). a and c Percentage of host cells infected vs. time for NTZ and AN7973, respectively. Data shown are the means and SD for 4 culture wells per data point and are representative of 4 independent experiments. b and d One-phase exponential decay curves fit for the highest non-cytotoxic concentration of NTZ and AN7973, respectively. b No exponential decay curve can be fit for NTZ. d Rapid parasite elimination by AN7973. Curves shown are for 3 × EC₉₀ (0.63 µM), 12 × EC₉₀ (2.5 µM) or the DMSO control. For both b and d, the data are referenced to the DMSO control at each time point, in order to isolate the effect of compounds from the spontaneous decline in parasite numbers that occurs in this C. parvum culture system. Data points are the means and SD for 4 culture wells per time point and are representative of 4 independent experiments