Fig. 2. GS-441524 derivatives exhibit antiviral activity against SARS-CoV-2 variants in vitro.

Vero E6 cells were infected with different strains of SARS-CoV-2(B.1, Beta, Delta and Omicron) at a multiplicity of infection (MOI) of 0.05 and treated with dilutions of the indicated compounds for 48 hours. Viral yield in the cell supernatant was then quantified by qRT-PCR [% inhibition= (viral RNA copies of treatment group / viral RNA copies of placebo control group) × 100]. The values of the concentration for 50% of maximal effect (EC₅₀) for each compound are shown above each plot and indicated with the red dashed line.