A Novel Mechanism of Restriction by an APOBEC3 Protein

描述（由申请人提供）：慢病毒都编码一种Vif蛋白，该蛋白已被证明与载脂蛋白mrna编辑、催化多肽样3 （APOBEC3）超家族蛋白的成员相互作用。APOBEC3蛋白是胞苷脱氨酶，被认为在先天抗病毒免疫中起重要作用。人类和猕猴都编码7个APOBEC3基因（A3A, A3B, A3C, A3D, A3F， A3G和A3H）。APOBEC3蛋白可大致分为单脱氨酶结构域（A3A、A3C和A3H）和双脱氨酶结构域蛋白（A3B、A3D、A3F和A3G）。人A3A （hA3A）不限制HIV-1 vif在293细胞或HeLa细胞中的复制，但最近被证明可以抑制巨噬细胞源性巨噬细胞（MDM）中HIV-1 vif的复制。相比之下，恒河猴的rhA3A能够限制HIV-1和SHIV（表达SIV Vif）。我们最近评估了其他非人灵长类动物A3A蛋白限制HIV-1和HIV-1 vif的能力。我们提供的初步数据表明，来自旧大陆猴，疣猴，colA3A蛋白不仅抑制HIV-1和HIV-1 vif的复制，而且还抑制产生细胞中的病毒产生。我们的初步研究表明，colA3A通过一种新的进入后机制抑制，而不是在原病毒整合之后。在Specific Aim 1中，我们提出确定colA3A抑制HIV-1复制的机制并评估所涉及的分子决定因素。在Specific Aim 2中，我们拟确定colA3A在人CD4+ T细胞和巨噬细胞中的表达是否能限制HIV-1在其自然感染的细胞中的表达。这些研究将为A3蛋白抑制HIV-1的新机制提供机制上的洞见，这可能作为一种新的抗病毒策略来对抗HIV-1。

DESCRIPTION (provided by applicant): The lentiviruses all encode for a Vif protein that has been shown to interact with members of the apolipoprotein mRNA-editing, catalytic polypeptide-like 3 (APOBEC3) superfamily of proteins. The APOBEC3 proteins are cytidine deaminases that are thought to play an important role in innate anti-viral immunity. Humans and macaques both encode for seven APOBEC3 genes (A3A, A3B, A3C, A3D, A3F, A3G, and A3H). The APOBEC3 proteins can be broadly divided into the single deaminase domain (A3A, A3C, and A3H) and double deaminase domain proteins (A3B, A3D, A3F, and A3G). Human A3A (hA3A) does not restrict the replication of HIV-1 vif in 293 cells or HeLa cells but has recently been shown to inhibit replication of HIV vif in macrophage-derived macrophages (MDM). In contrast, rhA3A from rhesus macaques is capable of restricting both HIV-1 and SHIV (expressing the SIV Vif). We recently have assessed the ability of other non-human primate A3A proteins to restrict HIV-1 and HIV-1 vif. We present preliminary data that the A3A protein from the Old World monkey, Colobus guereza (the mantled guereza, colA3A), not only inhibits the replication of HIV-1 and HIV-1 vif but also inhibits virus production in producer cells. Our preliminary studies indicate that the colA3A inhibits by a novel post-entry mechanism and, but not after, proviral integration. In Specific Aim 1, we propose to determine the mechanism though which colA3A inhibits HIV-1 replication and assess the molecular determinants involved. In Specific Aim 2, we propose to determine whether expression of colA3A in human CD4+ T cells and macrophages can restrict HIV-1 in cells it naturally infects. The proposed studies will provide mechanistic insight into this novel mechanism of A3 protein inhibition of HIV-1, which could serve as a new anti-viral strategy against HIV-1.