Cells
Vero E6 and COS-7 cells were purchased from the American Type Culture Collection (Manassas, VA, United States) and cultured in Dulbecco’s Modified Eagle’s Medium (DMEM; Thermo Fisher Scientific, Waltham MA, United States) supplemented with 10% fetal bovine serum (FBS; HyClone, Logan, UT, United States), 100 units/mL penicillin and 100 µg/mL streptomycin (Thermo Fisher Scientific). 293FT cells were purchased from Invitrogen (Carlsbad, CA, United States) and grown in DMEM supplemented with 10% FBS, 100 units/mL penicillin, 100 µg/mL streptomycin and 500 µg/mL geneticin (Thermo Fisher Scientific). Cells were maintained at 37 °C with 5% CO2.