Figure 1A. Immunoblot analysis of ACE2 expression in the lysate of human lung A549 cells overexpressing ACE2 compared to non-transduced (-) A549 cells. Calnexin served as loading control. B, C. Illustration of the Incucyte readout. Infection of A549 or ACE2-expressing A549 cells with SARS-CoV-2 encoding a GFP expression cassette. Infection of cells was monitored microscopically as green fluorescence through live-cell imaging at 24 hours post infection (hpi) (B) or during the time-course of 48 h and shown as the mean of the GFP-positive area relative to the whole area covered by cells in the same well (C). Error bars represent means ± SD derived from biological triplicates (N = 3). Scale bar, 500 µm. D. A549-ACE2 cells were treated for 6 hours with different concentrations of indicated inhibitors and then infected with SARS-CoV-2-GFP. GFP-fluorescence relative to DMSO-treated control cells was determined 48 hpi as described in (C). Two-sided independent Student's t-test with Benjamini-Hochberg FDR correction was performed for every indicated concentration compared to DMSO (0 µM). Asterisks indicate significance compared to DMSO (N = 3-6). Data information: Data are represented as means ± 95% CI from at least three independent experiments. *p < 0.05, **p < 0.01, ***p < 0.001. E. A549-ACE2 cells were treated for 30 min with PMA at indicated concentrations and then infected with SARS-CoV-2-GFP. Infection of cells was monitored as in C. Two-way ANOVA with Tukey's post-hoc multiple comparison test. Asterisks indicate significance compared to the DMSO control of each time point (N = 9). Data information: Data are represented as means ± 95% CI from at least three independent experiments. *p < 0.05, **p < 0.01, ***p < 0.001. F, A549-ACE2 cells were treated with apratastat, DPC-333 at indicated concentrations. Experiment was conducted and analyzed as in (D). Two-sided independent Student's t-test with Benjamini-Hochberg FDR correction was performed for every indicated concentration compared to DMSO (0 µM). Asterisks indicate significance compared to DMSO (N = 3-6). Data information: Data are represented as means ± 95% CI from at least three independent experiments. *p < 0.05, **p < 0.01, ***p < 0.001. G. A549-ACE2 cells were treated with apratastat, DPC-333 or BB94 at indicated concentrations. Experiment was conducted and analyzed as in (D). Two-sided independent Student's t-test with Benjamini-Hochberg FDR correction was performed for every indicated concentration compared to DMSO (0 µM). Asterisks indicate significance compared to DMSO (N = 3-6). Data information: Data are represented as means ± 95% CI from at least three independent experiments. *p < 0.05, **p < 0.01, ***p < 0.001. H, I. A549-ACE2 cells were treated for 1 h with indicated inhibitors (10 µM) or DMSO before inoculation with GFP-encoding spike pseudoparticles (VSV pseudotyped with SARS-CoV-2 spike protein (VSV-S)) (H) or as a control LCMV glycoprotein (VSV-GP) (I). At 16 hpi, infection was analyzed by counting GFP-positive cells. Data are normalized to the number of infected cells in virus-only control wells without DMSO (N = 3-5). One-way ANOVA with Tukey's post-hoc multiple comparison test. Asterisks indicate significance compared to DMSO. Data information: Data are represented as means ± 95% CI from at least three independent experiments. *p < 0.05, **p < 0.01, ***p < 0.001.