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

说明(申请人提供)：核苷逆转录酶抑制剂(NRTI)是临床上使用的最有效的抗逆转录病毒药物之一，经常用于艾滋病毒感染的一线治疗。然而，耐药在有艾滋病毒药物经验的患者中越来越常见，迫切需要确定和开发新的抗逆转录病毒药物，以对抗这些耐药的艾滋病毒毒株。所有被批准的NRTI都作为链终止子，因为它们缺乏3‘OH，并且长期以来一直存在的一个范例是，缺乏3’OH是抗病毒活性的关键。然而，这一特征也会给抑制剂带来不利的性质，例如与dNTP底物相比，对RT的亲和力降低，以及细胞内转化为活性核苷三磷酸的能力降低。我们和我们的合作者已经获得了挑战这一现有范式的新型核苷4‘-乙炔基，2-氟脱氧腺苷(4’E-2FdA)的数据。4‘E-2FdA是迄今为止描述的最有效的NRTI，尽管保留了可访问的3’OH，但仍充当链终止剂。我们的初步数据表明，这种明显的链终止是由于在掺入该化合物后，引物3‘-末端难以移位所致。因此，我们认为4‘E-2FdA是一种易位缺陷型逆转录酶抑制物(TDRTI)。我们推测，3‘OH、4’E和2F基团的存在有助于高效力，并导致了新的抑制机制。我们建议进行详细的生化研究，以更好地了解这些新的NRTI是如何工作的，并确定这些化合物的特定特性，这些特性有助于它们显着的抗病毒效力和出色的耐药性。为此，我们将追求以下具体目标：1.确定TDRTIs抑制RT的生化机制。2.用RT法确定TDRTI切除的生化机制。3.确定TDRTIs对临床相关NRTI耐药RTS的抑制作用；临床相关RT抑制剂与TDRTIs的相互作用以及联合用药的毒性。4.确定HIV对TDRTIs的耐药机制。解决这些目标应能极大地促进科学知识，并对设计新一代高度活跃的创新国家技术创新机构具有无价的价值。 与公共卫生相关：该项目将表征一类新型化合物的生化和分子基础，这些化合物极其有效地抑制艾滋病毒，通过这样做，它将有助于开发抗艾滋病毒疗法，这些疗法既不太容易受到当前临床上重大耐药性突变的影响，也更难产生病毒耐药性。

DESCRIPTION (provided by applicant): Nucleoside reverse transcriptase inhibitors (NRTIs) are among the most potent antiretrovirals used clinically, and are often used in first-line therapy for HIV infection. However, resistance is increasingly common in HIV drug experienced patients, and there is an urgent need to identify and develop new antiretrovirals active against these resistant HIV strains. All approved NRTIs act as chain terminators because they lack a 3'OH, and it has been a long standing paradigm that the absence of the 3'OH is essential for antiviral activity. However, this feature can also impart detrimental properties to the inhibitor, such as reduced affinity for RT compared to dNTP substrates, as well as reduced intracellular conversion to the active nucleoside triphosphate. We and our collaborators have obtained data with the novel nucleoside 4'-ethynyl, 2-fluoro deoxyadenosine (4'E-2FdA) that challenge this existing paradigm. 4'E-2FdA is the most potent NRTI described to date and acts as a chain terminator despite retaining an accessible 3'OH. Our preliminary data suggest that this apparent chain termination arises from difficulty of the primer 3'-terminus to translocate following incorporation of the compound. We therefore propose that 4'E-2FdA is a Translocation-Deficient Reverse Transcriptase Inhibitor (TDRTI). We hypothesize that the presence of the 3'OH, 4'E and 2F groups contribute to the high potency and result in the novel mechanism of inhibition. We propose to conduct detailed biochemical studies to better understand how these novel NRTIs work and to determine the specific characteristics of these compounds that contribute to their pronounced antiviral potency and excellent resistance profiles. To this end we will pursue the following Specific Aims: 1. Determine the biochemical mechanism of RT inhibition by TDRTIs. 2. Determine the biochemical mechanism of TDRTI excision by RT. 3. Determine inhibition of clinically relevant NRTI-resistant RTs by TDRTIs; interactions of clinically relevant RT inhibitors with TDRTIs and toxicity of combinations. 4. Determine the mechanism of HIV resistance to TDRTIs. Addressing these aims should significantly advance scientific knowledge and be invaluable in the design of new generations of highly active innovative NRTIs. PUBLIC HEALTH RELEVANCE: This project will characterize the biochemical and molecular basis for the unprecedented efficiency of a novel class of compounds that suppress HIV viruses extremely efficiently, and by doing so, it will help develop anti- HIV therapeutics that are both less susceptible to current clinically significant resistance mutations as well as more refractory to the development of viral drug resistance.