Ultrapotent Inhibitors of Wild-type and Multi-drug Resistant HIV

说明：核苷逆转录酶抑制剂(NRTI)是治疗HIV感染患者的高效抗逆转录病毒疗法(HAART)的关键成分。FDA批准的所有抗HIV NRTI都缺乏3‘-OH，因此通过立即链终止来抑制HIV RT的DNA聚合。与天然dNTP底物相比，3‘-OH的缺乏也降低了这些NRTI与RT的结合亲和力，并减少了细胞内向活性NRTI三磷酸的转化，从而赋予了这些NRTI有害的性质。我们在第一个资助周期中报告了4‘-乙炔基-2-氟-2’-脱氧腺苷(EFdA)是一种核苷类似物，它保留了3‘-OH部分，并显示出出色的抗病毒特性(在PBMC中EC50=50 PM)和显著的选择性指数(&gt；200,000)。EFdA的效力和选择性指数比目前批准的所有抗艾滋病毒药物都要有利几个数量级。尽管存在3‘-羟基，但被掺入的EFdA-单磷酸主要作为直接链终止子，因为RT难以在具有3’-末端EFdA-MP的引物上移位，这是一种独特的作用机制。因此，EFdA-TP是一种转位缺陷RT抑制因子(TDRTI)。此外，EFdA还被证明可以有效地抑制临床上重要的耐NRTI艾滋病毒株，并对耐替诺福韦的K65R艾滋病毒表现出超敏反应。值得注意的是，在我们对感染SIV的猕猴的研究中，使用EFdA治疗后抑制病毒载量的动物携带了M184V突变，这表明EFdA可以有效地抑制M184V。我们还表明，EFdA对艾滋病毒耐药具有非常高的屏障，许多耐EFdA的艾滋病毒株的复制能力降低。最近，我们已经证明了EFdA与利培韦林的结合显示出协同效应，这将在设计新的治疗方案中有用。我们将在第一个资助周期的工作基础上，了解EFdA在RT和细胞水平上的效力、EFdA耐药性的发展以及EFdA与目前批准的抗HIV药物的联合。我们还将使用生化和结构方法在RT水平上表征EFdA的抑制机制，脱氧胞苷激酶(DCK)激活EFdA的机制，以及腺苷脱氨酶(ADA)的脱氨作用。这项研究将提供指导设计新的NRTIs和EFdA与其他经批准的抗艾滋病毒药物的联合疗法的信息，这些药物可能导致艾滋病毒感染治疗的突破。

DESCRIPTION: Nucleoside reverse transcriptase inhibitors (NRTIs) are key components of Highly Active Antiretroviral Therapies (HAART) for the treatment of HIV-infected patients. All FDA-approved anti-HIV NRTIs lack a 3'-OH, and therefore inhibit DNA polymerization by HIV RT through immediate chain termination. The absence of a 3'-OH also imparts detrimental properties to these NRTIs by reducing their binding affinity for RT compared to the natural dNTP substrates and reducing intracellular conversion to active NRTI triphosphates. We have reported during the first funding cycle that 4'-ethynyl-2-fluoro-2'-deoxyadenosine (EFdA) is a nucleoside analog that retains the 3'-OH moiety and demonstrates exceptional antiviral properties (EC50 = 50 pM in PBMCs) and a remarkable selectivity index (>200,000). EFdA's potency and selectivity index is by orders of magnitude more favorable than all currently-approved anti-HIV drugs. Despite the presence of a 3'-OH, the incorporated EFdA-monophosphate acts primarily as an immediate chain terminator because RT has difficulty translocating on the primer possessing 3'-terminal EFdA-MP, which is a unique mechanism of action. Therefore, EFdA-TP is a Translocation-Defective RT inhibitor (TDRTI). Additionally, EFdA has also been shown to efficiently inhibit clinically-important NRTI-resistant HIV strains, and demonstrating hypersusceptibility to the tenofovir-resistant K65R HIV. Notably, in our study of SIV-infected macaques the animals that had suppressed viral loads upon treatment with EFdA carried the M184V mutation, suggesting that M184V can be effectively suppressed by EFdA. We have also shown that EFdA has a remarkably high barrier for HIV resistance, and many EFdA-resistant HIV strains have reduced replication capacity. More recently we have shown that the combination of EFdA with Rilpivirine shows a synergistic effect, which would be useful in the design of new therapeutic regimens. We will build on our work from the first funding cycle to understand the potency of EFdA at the RT and cellular levels, development of EFdA resistance, and EFdA combinations with currently-approved anti-HIV drugs. We will also use biochemical and structural approaches to characterize the inhibition mechanism of EFdA at the RT level, the activation of EFdA by deoxycytidine kinase (dCK) and deamination by adenosine deaminase (ADA). This study will provide information that will guide the design of novel NRTIs and EFdA combination therapies with other approved anti-HIV drugs that may lead to a breakthrough in the treatment of HIV infection.