Fig 3.

Adaptive evolution of the Nef and Vpu viral proteins in primate lentiviruses. The degradation of CD4 receptors by the Nef and Vpu viral proteins and their antagonistic activity against the restriction factor tetherin are represented by +, and the absence of these properties or very low activity is represented by −. The Nef proteins of SIVcpz and SIVgor degrade CD4 receptors and antagonize the factor tetherin in their respective hosts, whereas those of HIV-1 do not have any activity against human tetherin. Only the Vpu protein from HIV-1 group M, through adaptive evolution, possesses antitetherin properties and degrades CD4 receptors. (Reprinted from reference 26 with permission from Elsevier.)