2.8 Dose-response curve (DRC) analysis with SARS-CoV-2-Nluc
A549-ACE2-TMPRSS2 cells (1.2 x 104 cells per well)
were plated into white 384-well µClear plates (Greiner Bio-One). On the
next day, the cells were treated with 2-fold serial dilution of the
compound prepared in DMSO and infected with SARS-CoV-2-Nluc (MOI 0.01)
(Rihn et al., 2021). After incubation at
37°C for 24 hours, nanoluciferase substrates (Promega) were added to
each well and luciferase signals were measured using a
VICTOR3TM multilabel plate reader (PerkinElmer). Cell
viability was measured using the CellTiter-Glo Luminescent Cell
Viability Assay (Promega, Madison, WI, USA) according to the
manufacturer instructions. The relative luciferase signals of the
compound-treated groups were normalized to that of non-infection control
(set as 0%) and DMSO-treated groups (set as 100%). The DRCs were
generated using Prism6 software (GraphPad, San Diego, CA), and
IC50 (half-maximal inhibitory concentration) and
CC50 (half-maximal cytotoxic concentration) values were
calculated using a nonlinear regression model.