Extended Data Fig. 3: Results of SIA screening.

a, Analysis of CFIA results. Correlation chart between the percentage of syncytia per well and the total number of cells per well. Data are presented as in Extended Data Fig. 2e. b, Distribution frequency of the screening results. Data are shown as in Extended Data Fig. 2f. c, Correlation chart for the common drugs between the two libraries. Data are shown as in Extended Data Fig. 2g. d, Representative immunofluorescence images for spike protein (green), cell body (red, using HCS CellMask DeepRed) and nuclei (blue, Hoechst) of cells treated with the indicated drugs increasing syncytia formation compared to control, DMSO-treated cells. The number of syncytia is shown at the bottom of each image pair as percentages of total nuclei. Scale bar, 500 μm. Representative images in one of six wells. e, Dose–response effect on syncytia formation of niclosamide, clofazimine and salinomycin. The graphs show the effect of different doses of the three drugs on syncytia formed by Vero and HEK/ACE2 cells in response to spike expression. Cells were transfected with pEC117-Spike-V5 and, 12 h later, treated with the indicated drug concentrations for additional 24 h. Syncytia were quantified by high-content microscopy and are expressed as percentage of cell nuclei (n = 6 wells per dose; data are mean ± s.d.). Cell viability was assessed by high-content counts of the number of nuclei in each well.