PPCM reduction of EBOV GP-cell binding is dose-dependent (A, B) and PPCM interferes with MLV-Ebola early on the replication cycle (C, D).. (A) Percentage reduction of EBOV-GP bound to Vero, HeLa, or VK2/E6E7 when GP is preliminary incubated with decreasing concentrations of PPCM. (B) Detection of EBOV-GP1 by SDS-PAGE illustrating typical changes in GP binding efficacy to VK2/E6E7 cells when GP is preincubated with increasing concentrations of PPCM. (C) Percentage reduction of MLV-EBOV transduction in PPCM-pretreated compared to untreated HeLa cells. Results are expressed as the average of at least 2 biological replicates; error bars represent standard deviations. *, P < 0.05 **, P < 0.01 (ANOVA-Tukey’s multiple-comparison test). (D) One-parameter histograms plotting strawberry fluorescence signal intensity versus number of cells. Typical transduction levels of MLV-EBOV in HeLa cells preincubated with different concentrations of PPCM (left side). Control of complete inhibition of transduction was done by incubating MLV-EBOV with the neutralizing Mab S9 prior inoculation to cells (right side).