CD4 and HIV-1 infection: TREX1 downregulates the synthesis of IFN triggered by HIV-1 infection in both CD4+ T cells and macrophages; HIV-1 DNA accumulates in the cytoplasm in cells in which TREX1 is inhibited by RNA-mediated interference, although a modest induction of IFN-induced genes (ISG) can be observed upon infection [92,93].