Fig. 1

Representative images of 293T cells transduced with S-WT-EGFP, S-Δ19-EGFP and hACE2-mCherry vectors. A Top panels show the expression of EGFP and mCherry in 293T cells under reverse fluorescence microscope following transduction by lentiviral vectors. Bottom two rows show successful expression of S-WT-EGFP, S Δ19-EGFP, or hACE2-mCherry in 293T cells by high resolution confocal microscopy. Middle row represents DIC images. Bottom row represents merged confocal image (DAPI, blue; S-WT-EGFP or S-Δ19-EGFP, green; hACE2-mCherry, red). Scale bar equals 40 µm. Red arrow indicates cytosol spike protein, while white arrow indicates membrane bound spike protein. B The mean fluorescence intensities (MFI) of EGFP on the plasma membrane or cytosol of the cells were measured using multi-scale cell instance segmentation framework method, then plotted in a bar chart. P = 0.0001 when compare intensities of S-WT-M group with intensities of S-Δ19-M; P = 0.0060 when compare intensities of S-WT-Cy group with intensities of S-Δ19-Cy using nonparametric T-test (M = membrane, Cy = Cytosol)