Figure 4.

Inhibitory effect of PGG and PAC on the SARS-CoV-2 RdRp activity in the cell-based reporter assay system. A reporter plasmid, p(+)FLuc-(−)UTR-NLuc, and an RdRp expression plasmid, pCI-SARS2-nsp12N, were transfected in HEK293T cells. The cells were treated with serially diluted-PGG (A) and PAC (B) 6h later. After an 18 h incubation, the expression levels of FLuc and NLuc (left Y axis) were detected, and the NLuc/FLuc ratios (right Y axis) were calculated (left panel). Statistical comparisons were conducted using one-way analysis of variance (ANOVA), followed by Bonferroni’s multiple comparison test. * p < 0.05; *** p < 0.001; **** p < 0.0001 vs. 0 μM (left graph). The IC₅₀ values were determined using nonlinear regression analysis (right graph). The data are representative of three independent experiments, and presented as mean ± SEM.