The Glycoproteins of All Filovirus Species Use the Same Host Factors for Entry into Bat and Human Cells but Entry Efficiency Is Species Dependent

Hoffmann, Markus; González Hernández, Mariana; Berger, Elisabeth; Marzi, Andrea; Pöhlmann, Stefan

The mannose-polymer mannan and the serine protease inhibitor camostat mesylate did not inhibit filovirus GP-driven entry into any of the cell lines tested. Mannan was previously shown to block augmentation of GP-driven entry by DC-SIGN and other mannose-binding lectins [62, 75] , which are endogenously expressed on a subset of primary filovirus target cells. The most straightforward explanation for the inability of mannan to block entry in the present study is thus that none of the cell lines tested expressed mannose-specific lectins able to augment filovirus entry. Camostat mesylate inhibits activation of influenza A virus and coronavirus glycoproteins by the type II transmembrane serine protease TMPRSS2 [76] [77] [78] [79] . Filovirus GPs are activated by the pH dependent endosomal cysteine proteases cathepsin B and L, at least in several target cell lines [34, 35] , and that lack of inhibition of GP-driven entry by camostat mesylate was thus not unexpected.