Figure 2.

Model of pre-integration latency in HIV-1-infected microglia. Pre-integration latency is controlled by interaction of host restriction factors, including APOBEC3, SAMHD1, and MX2 in the monocyte- or macrophage-lineage cells. APOBEC3 plays a pivotal role in causing G to A hypermutation of the HIV-1 genome. In particular, SAMHD1 reduces the pool of dNTPs in macrophages by hydrolyzing them into their precursors (nucleosides and triphosphates), resulting in ineffective viral reverse transcription. Furthermore, MX2 restricts HIV replication in macrophages and microglia. Moreover, MX2 blocks HIV infection at the post-entry level by hindering the nuclear accumulation and integration of pro-viral DNA into host chromatin.