Figure 4.
Live-cell reporter enables high-throughput chemical screening for SARS-CoV-2 3CLpro inhibition. (A) 3CLpro inhibitor efficiency was evaluated in the reporter cells. Compounds were added at the indicated concentrations and incubated for 48 h, and inhibition was calculated as the percentage of luminescence signal relative to the vehicle-treated group. Data was plotted as mean ± SD, and statistical analysis was performed using a two-tailed Student’s t-test, N = 3, ** = p ≤ 0.01. (B) Schematic of the chemical screen methodology; cells were plated in 384 poly-lysine coated plates and incubated overnight. The following day, compounds were added at a concentration of 10 μM together with 100 ng/mL of doxycycline to induce 3CLpro expression. (C) Chemical screen result summary, the luminescence signal of treated cells was measured 48 h post-doxycycline induction, and signal percentage was calculated relative to the vehicle-treated group. Top leads were compounds that decreased the signal by 80% and more. (D) Inhibition efficacy and cell toxicity curves of PRT, EGCG, MND, IDX, and BEN. Each compound was tested at multiple concentrations, and compound toxicity and luminescent signal reduction was evaluated 48 h after addition. Data was plotted as mean ± SD, N = 3 for each concentration point, and nonlinear correlation analysis was used to evaluate compounds’ IC50.