Figure 2. SARS‐CoV‐2 makes differential use of host cell proteases for infectious penetration.

• A, B
  Cells were pretreated with the indicated concentrations of aprotinin (A) and SB412515 (B), which are inhibitors of TMPRSS2 and cathepsin L, respectively. Infection of Calu‐3, Caco‐2, A549*, and Vero cells with SARS‐CoV‐2 at MOIs of 0.3, 0.4, 0.2, and 0.3, respectively, was achieved in the continuous presence of the drug. Infected cells were quantified by flow cytometry as described in Fig 1D, and data were normalized to samples where inhibitors had been omitted. n = 2–4 biological replicates.
• C, D
  SARS‐CoV‐2 particles were bound to A549* and Vero cells (MOIs 0.2 and 0.3, respectively) (C) or Calu‐3 and Caco‐2 cells (0.6 and 0.5, respectively) (D) on ice for 90 min and subsequently warmed rapidly to 37°C to allow infectious penetration. SB412515 (10 µM, C) or aprotinin (30 µM, D) was added at different times postwarming to block further proteolytic activation. Infection was analyzed by flow cytometry, and data were normalized to samples where protease inhibitors had been omitted. n = 2.

Data information: (A, B) Data are expressed as mean ± SEM from two independent experiments. (C, D) Results are representative of 2–3 independent experiments and expressed as mean ± SEM of two biological replicates.

Source data are available online for this figure.