CD4 and HIV-1 infection: More recently, Nef-induced exosome-associated ADAM17 (ADAM metallopeptidase domain 17) had rendered resting CD4+ T cells permissive to HIV-1 infection [51], whereas ADAM17 along with TNF-α has been known to synergistically activate the latent HIV-1 in primary CD4+ T lymphocytes and macrophages [52].