Figure 4.

Ebola virus entry. (A) Lectins DC-SIGN and L-SIGN act as attachment factors to concentrate Ebola virus particles at the cell surface (Alvarez et al., 2002; Simmons et al., 2003), facilitating interaction with the receptor TIM-1. (B) Axl receptor tyrosine kinase is thought to promote virus particle uptake via macropinocytosis. Critically, Ebola virus does not directly engage Axl; the Axl ligand Gas-6 may associate with virus particles and facilitate indirect interaction between Ebola virus and Axl, as demonstrated for other viruses (Morizono et al., 2011). (C) Within the late endosome/lysosome, viral glycoprotein GP1 undergoes sequential proteolytic cleavage by cathepsins L and B, allowing interaction with NPC1, a putative endosomal receptor. Ebola virus membrane fusion is dependent on the viral glycoprotein GP2 and occurs from the late endosome/lysosome, although the exact molecular triggers remain unclear.