ERVW-1 and infection: In addition to antagonism by the HIV-1 Vpu, the Nef protein of various strains of SIV and the Env of HIV-2 antagonize BST2, and this Nef antagonism of BST2 is important during in vivo infection of rhesus macaques [335,336,337,338,339,340].Unlike their primate counterparts, mouse and rat BST2 orthologs cannot be counteracted by Vpu, Nef or HIV-2 Env [341].