12. IC50 (half-maximal inhibitory concentration) indicates the concentration of drug necessary to inhibit the action of a
process by half. High IC50 scores indicate resistance to antiviral drugs (in this case, Nirmatrelvir). Using the following
IC50 plot, indicate the IC50 values (see the figure, write the concentration at 50% inhibition) and IC50 fold increase (i.e,
how many times IC50 value for other variants increase with respect to wild type) for the use of Nirmatrelvir to following
SARS-CoV-2 3CLpro variants:
SARS-CoV-2 IC50 [µM] IC50 Fold
10pt
3CLpro
variant
Increase
from
Wild-type
n/a
Wild-type
Y54A/S144A
S144A/E166A
Percent Inhibition (%)
100
80
60
40
20
0
Wild-type 3CLpro
Y54A/S144A 3CLpro
S144A/E166A 3CLpro
0.001 0.01 0.1 1 10 100
[Nirmatrelvir] (µM)