Combination

The combination of OZ418 and RDV against OC43 was measured by Western blot. Two × 10⁶ HFFs were seeded in 6 well plates, and 2 wells were used for each condition. Cells were infected with OC43 (MOI = 1) for 1 h, washed, and then treated with various concentrations of OZ418 and RDV and their respective combinations for 72 h. Cells were lysed using lysis buffer containing protease inhibitors, and 25 μg of the lysate was analyzed by Western blot for detection of the OC43 antigen as mentioned earlier. The combination effect was tested in SARS-CoV-2-infected Calu-3 and Vero E6 based on the biomass determination in 12 well plates. Staining of the cell monolayers with 2% crystal violet in a 20% methanol solution was followed by solubilization in 10% acetic acid followed by OD determination at 595 nm. The relative biomass was calculated compared to noninfected cells and is represented as %.