Figure 1
From: Host hindrance to HIV-1 replication in monocytes and macrophages
Schematic representation of host restriction factors in human Mos and Mφ. On the left, low levels of CD4 and CCR5 may limit viral entry in monocytes. Low expression of thymidine phosphorylase associated with a limited stock of dTTP reduces RT rate. APOBEC3A and 3G may interfere with HIV-1 RT in Mos. HIV-2/SIV Vpx antagonizes the restriction of HIV-1 in Mos and Mφ by counteracting an unidentified host factor. Cellular miRNAs have been proposed to target the 3'UTR of HIV-1 transcripts. miR-198 may repress CycT1 expression that contributes to Tat transactivation. On the right, the CCR5Δ32 mutation restricts viral entry of R5 HIV-1 in Mφ. LPS targets the early phases of the HIV-1 cycle in Mφ, through the down-regulation of CCR5 expression and the LTR-driven transcription by IL-10/IFN-β-induced expression of 16 kDa C/EBPβ. p21Waf1 interferes with both RT and integration and is induced by FcγR engagement. CTIP2 and TRIM22 have been implicated in the inhibition of HIV-1 transcription. Urokinase-type plasminogen activator (uPA) blocks the release of viral particles from intracellular vacuoles.