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. 2021 May 19;22(10):5336. doi: 10.3390/ijms22105336

Figure 3.

Figure 3

Contribution of the various parts of the SDC4 ectodomain to SARS-CoV-2 uptake. GFP-tagged SDC4 mutants incubated with SARS-CoV-2 (at 1 MOI) for 18 h were fixed, permeabilized and treated with specific and AF 633-labeled SARS-CoV-2 antibodies. Cellular uptake was analyzed with imaging flow cytometry and confocal microscopy. (A) Schematic representation of the applied SDC4 mutants. (B) Representative flow cytometry histograms showing the intracellular fluorescence of SARS-CoV-2-treated SDC4 transfectants and mutants. (C) Detected fluorescence intensities were normalized to SARS-CoV-2-treated transfectants expressing WT SDC4 as standards. The bars represent the mean ± SEM of four independent experiments. Statistical significance vs. standards was assessed with ANOVA. ** p < 0.01; *** p < 0.01. (D) BF and fluorescent images of SARS-CoV-2-treated SDC4 mutants. Scale bar = 20 μm. The indicated BDS values of SARS-CoV-2 and SDCs represent the mean ± SEM of four independent experiments. Statistical significance between the SDC4 mutants was assessed with ANOVA. (E) Confocal microscopic visualization of SARS-CoV-2-treated SDC4, Si4, CBD and HSA transfectants. Scale bar = 10 μm. MOC ± SEM and PCC ± SEM for the overlap and colocalization of SARS-CoV-2 with SDC4, Si4, CBD and HSA (indicated below the images) was calculated by analysis of 15 images with ~10 cells in each image (from 3 separate samples). Statistical significance vs. SARS-CoV-2-treated transfectants expressing WT SDC4 (standards) was assessed with ANOVA. * p < 0.05, *** p < 0.001.