2.1 Cell lines
Human embryonic kidney 293T cells, cervical cancer HeLa cells, human liver Huh-7 cells, and African green monkey kidney Vero cells were cultured at 37°C, and 5% CO2 in DMEM (Gibco) supplemented with 8% fetal bovine serum (FBS) (Gibco), streptomycin, and penicillin (100 µg/ml). All cell lines were obtained from the American Type Culture Collection (ATCC).