CoV-2 was conducted under BSL-3 conditions at the German Primate Centre, Göttingen/Germany. Calu-3 cells were grown in 48-well plates until reaching approx. 70% confluency. Cells were incubated with 10-fold serial dilutions (10-0.001 μM) of inhibitors for 1 h at 37 °C prior to infection. Next, the inhibitorcontaining cell culture supernatant was removed, and cells were infected with SARS-CoV-2 isolate NK, Pango lineage B.1.513, at an MOI of 0.01 in an inoculum volume of 400 μL for 1 h at 37 °C. At 1 h p.i., the inoculum was removed, and cells were washed with PBS three times and further incubated in cell culture medium containing the respective inhibitor. Viruscontaining supernatants were harvested 24 h p.i. and stored at -80 °C until further usage. To determine viral titers, confluently grown Vero E6 cells were inoculated for 1 h at 37 °C with 10fold serial dilutions of virus-containing supernatants. Next, the inoculum was removed, and cells were washed once with PBS before they were overlaid with 1% plaque agarose (Biozym) dissolved in Eagle's minimal essential medium without phenol red (Lonza) and further incubated. At 48 h p.i., virus-induced plaques were counted, and viral titers were determined as PFU/mL.