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

These findings are in keeping with data documented for human cell lines [58] [59] [60] although previous studies documented a more robust effect, possibly due to differences in the pseudotyping system. Thus, furin cleavage motif and MLV are dispensable for GP-mediated transduction of human, primate and bat cells. Glycoprotein-driven entry into fruit bat and human cell lines depends on the same host cell factors We next investigated whether GP-mediated entry into fruit bat cells depends on the same host cell factors as described for human cells. To this end, we incubated human (HEK-293T) and fruit bat cell lines with inhibitors interrupting discrete steps of the entry process before pseudotypes harboring either of the filovirus GPs were added. We chose the fruit bat cell lines EpoNi/ 22.1 and EidNi/41 for these studies since they either showed a comparable susceptibility for transduction by all tested GPs or displayed varying susceptibility depending on which particular filovirus GP was used, respectively. For EidNi/41 cells, we only included VSVpp harboring SUDV-, TAFV-, RESTV-, MARV-and LLOV-GP, since transduction of pseudotypes decorated with EBOV1976-, EBOV2014-or BDBV-GP was only slightly above the limit of detection (Fig 1B) . On the side of the host cell factors we chose inhibitors ( Table 2 ) that targeted cellular lectins (mannan), endosomal acidification and thus indirectly cysteine protease activity (ammonium chloride, bafilomycin A1), cysteine proteases (E-64d; MDL28170), serine proteases (camostat mesylate), two-pore channels (tetrandrine) and NPC1 (U18666A, a compound that was recently shown to directly bind to NPC1 [61] ). Except for the serine protease inhibitor an inhibitory effect of these agents on GP-mediated entry into mammalian cells has been previously described [32, 35, 37, [62] [63] [64] [65] .