SGTA and AIDS: 20). Notably, HIV-1 and SIV Vpu proteins are genetically and functionally diverse, and this may affect the ability of the respective viruses to cross species barriers and to spread in new hosts. Specifically, HIV-1 group M strains that account for the AIDS pandemic encode Vpu proteins that counteract both tetherin and CD4, whereas the Vpu proteins of the rare or non-pandemic group N, O and P viruses are partly or completely lacking these functions19, 21, 22.