Targeting the HIV reservoir using optimized anti-HIV antibodies

使用优化的抗 HIV 抗体靶向 HIV 储存库

• 批准号: 9273865
• 负责人: Pamela J Bjorkman
• 金额: $ 41.08万
• 依托单位: CALIFORNIA INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-07-01 至 2022-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9273865
• 关键词: ADCC Assay; AIDS/HIV problem; Adverse effects; Anti-Retroviral Agents; Antibodies; Architecture; Avidity; Binding; Biological Assay; Cross-Linking Reagents; Crystallization; DNA; Drug resistance; Engineering; Epitopes; Evolution; Exhibits; Generations; Goals; HIV; HIV Antibodies; HIV-1; Half-Life; Homo; Immunity; Immunoglobulin G; In Vitro; Individual; Infection; Libraries; Linker DNA; Measures; Mediating; Molecular; Mutation; Patients; Persons; Pharmaceutical Preparations; Play; Population; Predisposition; Production; Public Health; Reagent; Research; Resistance; Role; Serum; Structure; Therapeutic; Therapeutic Uses; Time; Vaccines; Viral; Viral Load result; Viral reservoir; Virion; Virus; Virus Latency; antigen binding; base; cost; crosslink; density; design; experimental study; immunogenicity; improved; neonatal Fc receptor; neutralizing antibody; novel; prevent; protein structure; receptor; small molecule; synergism; viral rebound; viral resistance

Summary The rapid mutation rate of HIV-1 results in many thousands of viral strains, thus thwarting current vaccine efforts. Although HIV-1 infection can be controlled by anti-retroviral therapy (ART), the virus rebounds within weeks of ART cessation because complete elimination of HIV-1 is prevented by latent viral reservoirs. Broadly neutralizing antibodies (bNAbs) against the HIV-1 envelope spike (Env) that have been isolated from a subset of HIV-1–infected donors are protective against HIV-1 infection and can lower the viral load after infection, and it has been suggested that bNAbs could play a role in eliminating the viral reservoir. However, HIV-1 can evade even the most potent bNAbs by mutation. Here we seek to engineer bNAbs to be resistant to viral mutation so they could be used to eliminate viral reservoirs. Our strategy relies upon harnessing avidity effects to prevent viral resistance to bNAbs at both an individual and population level. We hypothesize that HIV-1 hinders IgGs from using both antigen-binding Fabs to bind bivalently. This is accomplished by the small number and low density of HIV-1 Env spikes, which prevent most IgGs from inter-spike crosslinking (bivalent binding between spikes), and the architecture of the Env trimer, which impedes intra-spike crosslinking (bivalent binding within a spike). We suggested that predominantly monovalent binding expands the range of HIV-1 mutations permitting Ab evasion, whereas reagents capable of bivalent binding through intra-spike crosslinking would be more potent across multiple strains of HIV-1. This hypothesis was supported by our demonstration of up to 100-fold increases in geometric mean potency achieved with our first generation intra- spike crosslinking reagents (homo- and hetero-diFabs joined by rigid DNA linkers). These results support the hypothesis that HIV's low spike density contributes to vulnerability of HIV-1 bNAbs to spike mutations and suggests that the ideal anti-HIV therapeutic for eliminating HIV reservoirs would utilize avidity to achieve intra- spike crosslinking because this sort of therapeutic would reduce the concentration required for sterilizing immunity and be resistant to Env mutations. Here we propose to design, produce, and evaluate second generation intra-spike crosslinking reagents with two improvements: (i) they will contain an IgG Fc to mediate effector functions and increase the serum half-life, and (ii) the DNA will be replaced by structured protein linkers. We will also evaluate the effects of Fc substitutions designed to enhance Fc-mediated effector functions through tighter binding to activating FcγR receptors and improve serum half-life through enhanced binding to FcRn, including a novel computational design strategy to improve binding to FcRn under conditions that promote increased IgG half-life. These more potent bNAbs could be used therapeutically at lower concentrations and thus reduce cost and/or production time, increase the number of patients being treated, and lower the potential for immunogenicity or other side-effects related to bNAb administration.

概括 HIV-1 的快速突变率导致产生数千种病毒株，从而阻碍了当前的疫苗 虽然 HIV-1 感染可以通过抗逆转录病毒治疗 (ART) 来控制，但病毒会在体内反弹。 ART 停止数周，因为潜伏病毒库阻止了 HIV-1 的完全消除。 针对 HIV-1 包膜刺突 (Env) 的中和抗体 (bNAb)，已从子集中分离出来 感染 HIV-1 的捐赠者对 HIV-1 感染具有保护作用，并且可以降低感染后的病毒载量，并且 有人认为 bNAb 可以在消除病毒库方面发挥作用，但 HIV-1 却可以。 在这里，我们试图通过突变来逃避最有效的 bNAb。 突变，以便它们可以用来消除病毒储存库，我们的策略依赖于利用亲和力效应。 为了防止病毒对个人和群体水平的 bNAb 产生耐药性，我们与 HIV-1 进行了斗争。 阻碍 IgG 使用两个抗原结合 Fab 进行二价结合，这是通过小分子实现的。 HIV-1 Env 尖峰的数量和低密度，可防止大多数 IgG 尖峰间交联（二价 尖峰之间的结合），以及阻碍尖峰内交联的 Env 三聚体的结构 （尖峰内的二价结合）。我们建议主要是单价结合扩大了范围。 HIV-1 突变允许抗体逃避，而试剂能够通过内尖峰进行二价结合 我们的研究支持了这一假设。 证明我们的第一代内部-几何平均效力提高了 100 倍 这些结果支持了尖峰交联试剂（由刚性 DNA 连接体连接的同源和异源 diFab）。 假设 HIV 的低尖峰密度导致 HIV-1 bNAb 容易发生尖峰突变，并且 表明消除 HIV 储存库的理想抗 HIV 疗法将利用亲和力来实现体内 尖峰交联，因为这种治疗剂会降低灭菌所需的浓度 在这里，我们建议设计、生产和评估第二个。 生成刺突内交联试剂，具有两项改进：(i) 它们将包含 IgG Fc 来介导 效应器功能并增加血清半衰期，并且 (ii) DN​​A 将被结构蛋白取代 我们还将评估旨在增强 Fc 介导效应器的 Fc 替换的效果。 通过与激活的 FcγR 受体更紧密地结合来发挥作用，并通过增强 与 FcRn 的结合，包括一种新颖的计算设计策略，以改善在一定条件下与 FcRn 的结合 这些更有效的 bNAb 可以在较低的剂量下用于治疗。 浓度，从而降低成本和/或生产时间，增加接受治疗的患者数量， 并降低与 bNAb 给药相关的免疫原性或其他副作用的可能性。