2.4 Cells and viruses
H1299 cells were obtained from the Korean Cell Line Bank (KCLB, South Korea, 25803) and cultured in RPMI-1640 (Gibco, USA). HEK293T and Vero cells were obtained from the American Type Culture Collection (CRL-3216 and CCL-81) and cultured in Dulbecco’s Modified Eagle’s Medium (DMEM; Corning, USA), respectively. Both culture media were supplemented with 10% fetal bovine serum (FBS) (Gibco, USA) and 1X Penicillin-Streptomycin solution (HyClone, USA). Cell cultures were incubated at 37°C in a humidified incubator containing 5% CO2. For viruses, early isolates of SARS-CoV-2 viruses (NCCP43326) and four SARS-CoV-2 variants including Alpha (NCCP43381), Beta (NCCP43382), Delta (NCCP43390), and Omicron (NCCP43408) were obtained from Korea Disease Control and Prevention Agency (KDCA). These viruses were propagated in Vero E6 cells and the viral titers were determined by plaque assay using Vero cells. All experiments with these viruses were conducted in an enhanced biosafety level 3 (BSL‐3) containment facility at Institut Pasteur Korea as approved by the KDCA.