Fig. 5.
SFL pseudotyped with E, M,andN helper packaging can effectively help SFL infect cells. A. Fluorescence images of SFL PVs with helper packaging after 48 h and 72 h cell infection. 72 h packaging SFL PVs cannot infect 293 T-ACE2 while 72 h packaging SFL PVs with M, E or M, E, N helper packaging infect cells successfully. But 72 h packaging Sdel18 PVs with N helper packaging without infectivity of budding viruses (Scale bar = 100 µm). Experiments were done twice and one representative is shown. B. SARS-CoV-2 S protein PVs were cleaved successfully when infecting the cells triumphantly by western blot. uncleaved S protein, about 180 kDa; cleaved S protein, about 100 kDa. C. PVs with E, M, and N helper packaging in 72 h show similar results. The total amount of uncleaved and cleaved spike molecules was calibrated for SARS-CoV-2 PVs entry. Experiments were done twice and one is shown.