Fig. 2.

Entry driven by the glycoproteins of the four Ebola virus species depends on cathepsin activity. A. 293T target cells were preincubated with the indicated concentrations of cathepsin B and L inhibitors (MDL28170, E64c), a serine protease inhibitor (AEBSF) and an inhibitor blocking cysteine and serine proteases (leupeptin). Subsequently, cells were infected with pseudotypes bearing the indicated GPs, normalized for equal infectivity. Luciferase activity in cell lysates was measured at 72 h post infection. B. The experiment was carried out as described in (A), using two different concentrations of cathepsin L inhibitor III and cathepsin B inhibitor CA074. C. The experiment was carried out as described in (A) but cells were incubated with the cathepsin B inhibitor CA074Me. The results of representative experiments performed in triplicates are shown in A–C; error bars indicate SD. Similar results were obtained in three separate experiments.