The myosin inhibitor BDM inhibits hemoglobin transport to the DV and parasite development. (A) IRBC were treated for 26 h with increasing concentrations of BDM beginning at 6 to 18 h postinvasion, and the level of parasitemia was determined at 32 to 44 h (TP1) or 48 to 56 h (TP2) postinvasion. BDM at 25 or 50 mM is parasiticidal (TP1). BDM strongly inhibits growth at 2.5 mM, whereas it essentially eliminates parasitemia at 25 or 50 mM. (B) 3D model of a parasite that was treated with 25 mM BDM for 30 min. Note the appearance of a long, hemoglobin-filled tube that lacks a cytostomal collar. (C) JAS and BDM treatments cause similar increases in the surface area-to-volume ratio of the hemoglobin-containing tubes. (D) Representative single-section electron micrograph of an IRBC that was treated for 3 h with the protease inhibitor E64. The asterisk indicates a DV swollen with undigested hemoglobin. (E) Representative single-section electron micrograph of an IRBC treated for 4 h with the protease inhibitor E64 and the myosin inhibitor BDM. The asterisk indicates a DV that is devoid of hemoglobin, showing that BDM treatment prevents hemoglobin from trafficking to the DV. Scale bars, 500 nm. (F) Graph comparing the percentages of hemoglobin-filled DV in IRBC treated with E64 and those treated with BDM and E64. n = 100.