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 filovirus glycoprotein (GP) is the only viral protein embedded in the viral envelope and constitutes the sole determinant of host cell entry [19] . In addition, the GP is a virulence factor [20, 21] . The filovirus GP is synthesized as a precursor protein (GP 0 ), which is extensively modified by N-and O-glycans and processed by subtilisin-like proprotein convertases (especially furin) during passage through the secretory pathway [22] . Cleavage occurs between the surface unit, GP1, which contains the receptor binding domain (RBD) and a mucin-like domain (MLD), and the transmembrane unit, GP2, which anchors the GP in the viral envelope and harbors the membrane fusion machinery (Fig 1B) . Although the cleavage motifs for proprotein-convertases are found in all filovirus GPs (RESTV-GP contains a non-classical furin recognition motif [22] ), processing of EBOV-GP by these enzymes is dispensable for robust viral spread in cell culture and in the host [23, 24] .