Fig. 3
From: A novel luciferase-based assay for quantifying coronavirus-induced syncytia
Upregulation of the ssTau-split Gluc signal via FCoV infection. (a) Gluc activity in the medium of cells transfected with a Gn/Gc pair of four Tau-split Gluc constructs (a split Gluc fragment (Gn or Gc) at the N- or C-terminus of Tau) in Fcwf-4 and CRFK cells. (1) Vect: Empty expression vector, (2) TGn: ssTau-Gn, (3) TGc: ssTau-Gc, (4) GnT: ssGn-Tau, (5) GcT: ssGc-Tau. The data are expressed as the mean ± standard deviation (SD), with raw values of each well indicated as circles (○). The luciferase values relative to cells transfected only with empty vectors are indicated at the top of each bar. (b) Quantification of FCoV-induced cell‒cell fusion using the ssTau-split Gluc system at 24 h post-infection. The transfected vectors and viral infections in each group are indicated in bar graphs. Ctrl: Non-infected control cells. The data are expressed as the mean ± SD, with raw values of each well indicated as circles. The luciferase values relative to non-infected cells with TGn + TGc vector are shown at the top of each bar. (c) Correlation between viral dose and split-Gluc restoration. The mean luciferase value of each group was used for the analysis. The data are expressed as the mean ± SD, with raw values of each well indicated as circles. MIC: Maximal information coefficient20. (d) Effects of GS-441524 on FCoV-induced syncytial formation of Fcwf-4 cells. Luciferase activity at various GS-441524 doses is shown. The data are expressed as the mean ± SD. (e) Inhibition of split-Gluc restoration by GS-441524. The percentage of inhibition was calculated based on the luciferase activity results shown in panel d. The data are expressed as the mean ± SD, with raw values of each well indicated as circles. (f) Effects of GS-441524 on cell survival. Cell viability was assessed using the WST-8 assay after the determination of split-Gluc values. The data are expressed as the mean ± SD, with raw values of each well indicated as circles. (g) Inhibition of cell death by GS-441524. The percentage of inhibition was calculated based on the WST-8 assay results shown in panel (f).
