FIG. 4.

TMPRSS2 does not affect virus production. (A) SDS-PAGE and Western blot analysis were performed to detect S protein in cell lysates (cell) and culture medium (med) of Vero or Vero-TMPRSS2 (Vero-TM2) cells at 20 h after SARS-CoV infection (left panel). Cells treated with 10 μg/ml trypsin (tryp) at 37°C for 5 min were used as a cleaved-S control. Influenza virus (Flu)-HA produced by plasmid transfection was also used as a cleavage control (right panel). (B) Infectivity of SARS-CoV produced in Vero or Vero-TMPRSS2 cells. Vero-E6 cells were infected with SARS-CoV produced in either Vero or Vero-TMPRSS2 cells in the presence of 5 μM HR2 peptide or 500 nM bafilomycin A1 and then cultured for 5 h. The amount of viral mRNA9 was measured by real-time PCR. Cells not treated with reagents were used as controls. The error bars are standard deviations of at least six independent measurements.