Fhs 74 int cells

A non-transformed human fetal small intestinal epithelial cell line (FHs 74 Int cells) was purchased from ATCC and cultured in DMEM with 10% (v/v) FBS, an antibiotic-antimycotic solution, and 30 ng/ml human epidermal growth factor (all from Gibco) at 37 °C in a humidified atmosphere at 5% (v/v) CO₂. The medium was changed every 2–3 days.

A non-transformed human fetal small intestinal epithelial cell line (FHs 74 Int cells) was purchased from ATCC (ATCC, Manassas, VA, USA) and cultured in DMEM with 10% (v/v) heat-inactivated fetal bovine serum (FBS), an antibiotic–antimycotic solution, and 30 ng/ml human epidermal growth factor (all from Gibco, Grand Island, NY, USA) at 37 °C in a humidified atmosphere at 5% (v/v) CO₂. The medium was changed every 2–3 days.

PD was obtained from the Meilun Biological Company (China). Xylene, ethanol, and ethylenediaminetetraacetic acid (EDTA) were purchased from the Sinopharm Chemical Reagent Co., Ltd. Anti-Ki-67 antibody was purchased from the BD Company, cleaved caspase-3 antibody was purchased from the Cell Signaling Company, and CD31 antibody was purchased from Abcam. The FHs74Int cells were obtained from the American Type Culture Collection (ATCC). The CCK-8 kit was purchased from the Biotool Company (USA). The multi-functional microplate reader was obtained from Molecular Devices (USA). The microscope was purchased from Olympus (Japan).

Human embryonic kidney 293T (293T) cells, human lung alveolar epithelial (A549) cells, and human fetal small intestinal epithelial (FHs 74 Int) cells were obtained from American Type Culture Collection (ATCC) (Manassas, VA, United States). All cell lines were cultured in Dulbecco’s modified Eagle’s medium (DMEM) with 1% penicillin-streptomycin and 10% fetal bovine serum (FBS) in a humidified atmosphere, 5% CO₂ at 37°C. All the peptides were purchased from GL Biochem (Shanghai, China). Mpro and NRP-1 were purchased from Abcam (Cambridge, MA, United States). The SARS-CoV-2 pseudovirus was obtained from ACROBiosystems (Newark, DE, United States). Peptide-21 and EG3287 were purchased from GL Biochem (Shanghai, China).