English: "Schematic Representation of the Key Structural Features of SIV and HIV-1 Entry into T Cells"

(A) Different stages of viral entry from budding, to maturation, to entry claw formation. For the SIV strain used here, viruses that are docked to the cell via an entry claw show very few, if any, viral spikes on their surface, whereas non-contacting viruses typically display between 60 and 100 spikes on their surface. The entry claw is composed of between five to seven anchors spanning the region between the virus and the cell, each ∼100 Å long, and spaced laterally by ∼150 Å.

(B and C) Two alternative models for viral entry. In the global fusion model (B), the formation of the entry claw is followed by progressive fusion of the viral membrane across its width, leading to merger of the contents of the viral membrane with the cellular membrane. In the local fusion model (C), the formation of the entry claw is followed by the creation of a local pore centered at one of the rods, leading to delivery of the viral core into the cell."