HIV-1 Maturation

HIV-1成熟

• 批准号: 10262147
• 负责人: eric freed
• 金额: $ 69.71万
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10262147
• 关键词: Adverse effects; Anti-Retroviral Agents; Antiviral Agents; Betulinic Acid; Binding; Biochemical; Capsid; Cells; Cleaved cell; Clinical Trials; Collaborations; Conduct Clinical Trials; Development; Foundations; Generations; Genetic Polymorphism; Goals; HIV-1; Link; Maps; Molecular; Mutation; Pathway interactions; Patients; Peptide Hydrolases; Peptides; Pharmaceutical Preparations; Pharmacologic Substance; Phytic Acid; Play; Polyproteins; Preclinical Testing; Property; Research; Resistance; Role; SP1 gene; Site; Structural Biologist; Structure; Structure-Activity Relationship; Techniques; Time; Toxic effect; Viral; Viral Load result; Virus; Work; analog; antiretroviral therapy; gag Gene Products; inhibitor/antagonist; insight; multidisciplinary; mutant; novel; resistance mutation; response; structural biology; viral resistance

While currently available antiretroviral therapies are highly effective in suppressing HIV-1 replication in treated patients, these drugs are not curative. Patients are thus required to remain on continuous, lifelong therapy, which has been associated with a variety of toxicities and adverse effects. Also, over time, viral resistance is likely to pose an increasingly serious problem for patients on therapy. The development of novel classes of inhibitors that block steps in the replication cycle distinct from those targeted by currently available drugs is therefore a high priority. We have played a leading role in the development of one such novel class of HIV-1 antiviral drugs, the maturation inhibitors (MIs)._____In the HIV-1 replication cycle, Gag proteins are synthesized as a polyprotein precursor (Pr55Gag) that is cleaved by the viral protease (PR) during virus release from the infected cell. Completion of the Gag processing cascade is essential for virus maturation and infectivity. In collaboration with Panacos Pharmaceuticals, we found that 3-0-(3'-3'-dimethylsuccinyl) betulinic acid (PA-457, now known primarily as bevirimat or BVM) potently inhibits HIV-1 maturation by specifically blocking a late step in the Gag-processing pathway, the conversion of the capsid-spacer peptide 1 (CA-SP1) region of HIV-1 Gag to mature CA. Clinical trials conducted with BVM produced mixed results; in some patients, significant reductions in viral loads were achieved, whereas in other patients, no benefit of BVM therapy was observed. We and others demonstrated that this lack of response was linked to polymorphisms in SP1. We have also studied in detail the target, mechanism of action, and resistance pathways of a second, structurally distinct MI discovered by Pfizer (PF-46396 or PF96). We found that resistance to PF96 was conferred by mutations not only in the vicinity of the CA-SP1 cleavage site [where resistance to BVM maps] but also upstream in the CA major homology region (MHR). Notably, the MHR mutants that arose during selection for PF96 resistance were markedly PF96 dependent. The MHR mutants, which on their own are highly deficient in assembly and replication, could also revert by acquiring a second-site mutation in SP1 residue 8 (T8I). The study of the PF96-dependent MHR mutants and the T8I compensatory mutant is providing a wealth of information about the role of CA and SP1 in assembly and maturation and will advance our understanding of the structural properties of SP1. Our research on BVM and PF96 has provided novel insights into the structure-function relationship between CA and SP1, as well as a framework for increased structural understanding of HIV-1 MI activity._____We have now forged a multidisciplinary collaborative effort, together with chemists in Dr. Joel Schneider's lab (NCI), at DFH Pharmaceuticals, and at the Hetero Research Foundation (HRF), to develop "second-generation" BVM analogs that are significantly more potent and broadly active against polymorphic isolates of HIV-1 than BVM or PF96. The best of these analogs are undergoing preclinical testing in anticipation of clinical trials. More long term, we hypothesize that defining the structure of the MI-binding pocket in HIV-1 Gag will greatly facilitate the development of novel and more potent inhibitors; to this end, we are collaborating with several structural biology labs to define the structure of the CA-SP1 region in the immature Gag lattice, in both the presence and the absence of bound inhibitor. Our working hypothesis is that MIs block CA-SP1 processing by stabilizing a six-helix bundle that extends from the C-terminus of CA into SP1. Resistance mutations confer escape by stabilizing this helical bundle. We are collaborating with structural biologists to define the structure of MI-bound Gag by NMR techniques. We are also studying the effect of inositol hexakisphosphate (IP6) on MI activity. We believe that our work in this project will be transformative both in understanding the structure and function of the CA-SP1 region of Gag, which plays critical roles in HIV-1 assembly and maturation, and in developing MIs as a novel class of antiretroviral agents.

虽然目前可用的抗逆转录病毒疗法在抑制治疗患者的HIV-1复制方面非常有效，但这些药物尚未治愈。因此，需要患者继续进行终身治疗，这与多种毒性和不良反应有关。同样，随着时间的流逝，病毒抗性可能对治疗患者构成越来越严重的问题。因此，在复制周期中阻止与当前可用药物靶向的新型抑制剂的新型抑制剂的开发是一个很高的优先级。我们在一种此类新型HIV-1抗病毒药物，成熟抑制剂（MIS）的开发中发挥了领先作用。在HIV-1复制周期中，GAG蛋白在从病毒蛋白酶中裂解的杂种蛋白（PR55GAG）合成为多蛋白前体（PR55GAG），在病毒蛋白酶中释放在病毒蛋白酶中（PR）。完成插科打加工级联对于病毒的成熟和感染性至关重要。 In collaboration with Panacos Pharmaceuticals, we found that 3-0-(3'-3'-dimethylsuccinyl) betulinic acid (PA-457, now known primarily as bevirimat or BVM) potently inhibits HIV-1 maturation by specifically blocking a late step in the Gag-processing pathway, the conversion of the capsid-spacer peptide 1 (CA-SP1) region of HIV-1堵嘴到成熟的ca。用BVM进行的临床试验产生了不同的结果。在某些患者中，病毒载量的显着降低，而在其他患者中，没有观察到BVM治疗的好处。我们和其他人表明，这种缺乏反应与SP1中的多态性有关。我们还详细研究了辉瑞（PF-46396或PF96）发现的第二个结构上不同的MI的目标，作用机理和电阻途径。我们发现，对PF96的耐药性不仅是由CA-SP1裂解位点附近的突变（其中对BVM地图的耐药性），而且在CA主要同源区（MHR）上游的突变。值得注意的是，在选择PF96抗性期间出现的MHR突变体明显取决于PF96。 MHR突变体本身在组装和复制方面高度不足，也可以通过在SP1残基8（T8i）中获得第二位突变来恢复。对PF96依赖性MHR突变体和T8i补偿性突变体的研究提供了有关CA和SP1在组装和成熟中的作用的大量信息，并将促进我们对SP1结构特性的理解。我们对BVM和PF96的研究为CA和SP1之间的结构功能关系提供了新的见解，以及增加对HIV-1 MI活动的结构理解的框架。与BVM或PF96相比，针对HIV-1的多态性分离株的BVM类似物明显更有效且广泛地活跃。在预期临床试验时，这些类似物中最好的类似物正在进行临床前测试。更长远，我们假设定义HIV-1插科打gag的MI结合口袋的结构将极大地促进新颖和更有效的抑制剂的发展。为此，我们正在与几个结构生物学实验室合作，以在存在和不存在结合抑制剂的情况下定义了未成熟插入晶格中CA-SP1区域的结构。我们的工作假设是，通过稳定从CA的C末端延伸到SP1的六螺旋束来进行MIS Block CA-SP1处理。电阻突变通过稳定这个螺旋束来避免逃脱。我们正在与结构生物学家合作，以通过NMR技术来定义MI-BON-BOND的结构。我们还研究了肌醇六磷酸（IP6）对MI活性的影响。我们认为，我们在该项目中的工作将在理解CA-SP1区域的结构和功能方面具有变革性，该区域在HIV-1组装和成熟中起着至关重要的作用，以及作为新型抗逆转录病毒药物的新成熟。