HEK293 cells (human embryonic kidney cell line) and Vero cells (African green monkey kidney cell line) were obtained from the RIKEN BioResource Center Cell Bank. Vero/TMPRSS243 (link) were obtained from the Japanese Collection of Research Bioresources Cell Bank. 293T cells were maintained in Dulbecco’s modified Eagle’s Medium (DMEM) containing 10% fetal calf serum (FCS). Vero cells and Vero/TMPRSS2 cells were maintained in DMEM containing 5% FCS and 1 mg/ml G418 (Invivogen) was added to the growth medium for Vero/TMPRSS2 cells.
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