CTSS and infection: To further investigate the proteolytic activation of unprimed rVSV∆G EBOV preGP in VeroE6 and Huh-7 cells, infections were performed under single and combined furin (MI-1148), endosomal cathepsins (E64d) and trypsin-like protease (BAPA) inhibitor treatment for 72 h (Fig. 1C, middle and right panels).