The phosphatidylinositol-3-phosphate 5-kinase inhibitor apilimod blocks filoviral entry and infection
(A-D) BSC-1 cells were pretreated with DMSO (Mock), 20 μM nocodazole, or 0.2 μM apilimod for 1 h at 37°C. VLPs were then bound to cells by spinfection in the presence of the indicated drug, and the cells were then washed and incubated in the presence of the indicated drug for 90 min at 37°C. The cells were then washed, fixed, permeabilized, stained, and analyzed for VLP colocalization with NPC1. (A) Average Manders colocalization coefficients (± SD) from 2 experiments (n = 45 fields each treatment). Each data point (blue dot, triangle or square) represents the Manders colocalization coefficient for 1 image field. (B-D) Representative micrographs of cells treated with (B) DMSO, (C) 20 μM nocodazole, or (D) 0.2 μM apilimod. Scale bars, 10 μm (primary images) and 1μm (insets). ***p<0.001. (E) VLP colocalization with NPC1 was monitored as above except that samples were fixed at 0, 30, 60 or 90 min. Data are the Manders colocalization coefficients from 24–29 microscope fields per sample. Values are averages ± SEM. Apilimod-treated samples were statistically different from mock (***p < 0.0001) at 60 and 90 min.