Virus particles attach to the cell-surface through the interaction between GP and some cellular molecules (e.g., putative ubiquitous receptors, C-type lectins). Following virus uptake and trafficking to late endosomes, GP is cleaved by cellular proteases such as cathepsins to remove heavily glycosylated regions including the MLR and expose the RBR of GP1. Binding of cleaved GP1 to a coreceptor (e.g., NPC1) might be necessary for the GP conformational change leading to membrane fusion.