FIG 4.
PKC inhibitors play an antiviral role during the early stage of SARS-CoV-2 replication. (A to E) Effect of PKC inhibitors on protein translation. BHK-21 cells were pretreated with DMSO or the indicated inhibitors for 1 h, followed by transfection with SARS-CoV-2 replicon RNA, GFP- or Renilla luciferase-expressing plasmids, or ZIKV replicon RNA. Luciferase assays or Western blot assays were performed at the indicated hours after transfection. MW, molecular weight; RLU, relative luciferase units. (F) Effect of PKC inhibitors on 3CLpro activity. The protein activities were determined using a 2019 nCoV Mpro/3CLpro inhibitor screening kit. SARS-CoV-2 3CLpro, the substrate, and the inhibitors were incubated at 37°C for 5 min, and luciferase activities were measured at 490 nm using a multimode plate reader. Ebselen was used as a positive control. Data are presented as means ± SD from three experiments. P values were calculated by ANOVA with Dunnett’s multiple-comparison test or unpaired, two-tailed Student’s t tests (*, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001; NS, not significant).