The activating ligands included NTB-A, which binds NTB-A on the NK cell surface and leads to activation and secretion of interferon-γ, CD48, which binds 2B4, ULBP-1 and -2, ligands that bind NKG2D and that have been demonstrated to be upregulated in the setting of HIV-1 infection by the viral protein vpr (32), and CD155, a NK ligand that binds DNAM-1 on NK cells and induces activation (33). Here, SLAMF6 is linked to HIV-1 infection.