2.9 Luciferase activity assay
One day before viral infection, 1×104 Vero cells were seeded in 96-well plates. Virion-containing supernatants were then added to Vero cells. After 48 h, the cell culture was terminated. Cells were washed with PBS 3 times and lysed with 100 μL of RIPA buffer. 100 μL of cell lysate was taken, mixed with an equal amount of substrate (Bright-Glo luciferase assay system, Promega) for 10 min at RT, and used for luminescence activity measurement.