APOBEC3 family proteins mediate HIV-1 restriction in myeloid cells

最初的目标是阐明APOBEC3(A3)介导的HIV-1在THP-1细胞中的限制，作为HIV-1感染的髓系细胞的模型。我们使用CRISPR方法创建了A3F和A3F/A3G空THP-1克隆。HIV-1 Vif降解A3蛋白以便在HIV-1感染的CD4T细胞中有效复制。在THP-1细胞中，破坏的A3F和A3F/A3G蛋白完全恢复了Vif缺陷的HIV-1的传染性。此外，所有A3蛋白(A3缺失的THP-1)的破坏也导致Vif缺陷的HIV-1的感染性恢复。然而，我们发现内源性A3H不参与THP-1细胞对HIV-1的限制。此外，我们得出结论，A3蛋白对HIV-1感染的限制是通过依赖脱氨酶(G-to-A突变)和脱氨酶不依赖的机制(反转录产物的积累)来介导的。综上所述，我们的结果表明，A3蛋白是HIV-1 Vif被降解的主要靶点，以确保HIV-1在THP-1细胞中有效复制。

Initial goal is to clarify the APOBEC3 (A3)-mediated restriction of HIV-1 in THP-1 cells, as a model for HIV-1-infected myeloid cells. We created A3F and A3F/A3G-null THP-1 clones using CRISPR approach. HIV-1 Vif degrades A3 proteins in order to replicate efficiently in HIV-1-infected CD4 T cells.In THP-1 cells, disrupted A3F and A3F/A3G proteins fully restored infectivity of Vif-deficient HIV-1. Also, disruption of all A3 proteins (A3-null THP-1) also resulted in restoration of infectivity of Vif-deficient HIV-1. However, we found that endogenous A3H is not involved in HIV-1 restriction in THP-1 cells.Furthermore, we concluded that restriction of HIV-1 infection by A3 proteins is mediated through a deaminase-dependent (G-to-A mutations) and deaminase-independent mechanisms (accumulation of reverse transcription products). Collectively, our results indicate that A3 proteins are primary target of HIV-1 Vif to be degraded, in order to secure efficient HIV-1 replication in THP-1 cells.