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Unlocking Envelope: A New Strategy for a Functional Cure Through Antibody-Dependent Cell-Mediated Cytotoxicity

解锁包膜：通过抗体依赖性细胞介导的细胞毒性实现功能性治愈的新策略

基本信息

批准号：
10176380
负责人：
Marzena Elzbieta Pazgier
金额：
$ 44.44万
依托单位：
HENRY M. JACKSON FDN FOR THE ADV MIL/MED
依托单位国家：
美国
项目类别：
财政年份：
2019
资助国家：
美国
起止时间：
2019-05-03 至 2023-09-30
项目状态：
已结题

项目摘要

Project Summary/Abstract Strategies for a functional cure with use of non-neutralizing antibodies (nnAbs) that eliminate HIV-infected cells through Fc receptor (FcR) effector function including antibody dependent cellular cytoxicity (ADCC) remain a significant yet largely unexploited avenue of research.This project is designed to test the hypothesis that conjugates of CD4-mimetic miniprotein M48U1 and nnAbs specific for epitopes in the first and second constant (C1-C2) region of HIV-1 Env (A32-region or Cluster A epitopes) will develop into therapeutic antibodies (tAbs) capable of efficient reduction of the infected cell reservoir in infected individuals on ART thus develop into agents capable of a functional cure exclusively through FcR-effector mechanisms. This hypothesis will be tested using set of anti-Cluster A nnAbs which recognize highly conserved and functionally critical regions of gp120 which provide breadth of killing while minimizing the possibility of epitope escape. We have characterized these epitope targets at atomic and mapped them to the discontinuous sites involving highly conserved residues of the g120 inner domain. These regions in unliganded Env trimers are important for trimer stability and are inaccessible for antibody recognition until interactions of the Env spike with the cellular CD4 receptor. Our recent data indicate that exposure of these targets on the infected cell is limited by the low levels of surface CD4 that could effectively trigger Env trimers emerging on the cell surface. This represents a highly sophisticated mechanism put in place by HIV to prevent antibody-mediated clearance of virally infected cells. We were able to overcome the unfavorable exposure of these A32-region epitopes on infected cells with a CD4-mimetic molecule, the miniprotein M48U1 which binds within the CD4 binding site of Env trimers and triggers them to assume the CD4-bound conformation required to expose the A32-region epitopes on the surface of infected cells in the sera of HIV-1 infected individuals. Accordingly, by conjugating the M48U1 with the appropriate linker to the anti- Cluster A nnAbs we aim to develop new tAbs capable of sensitizing HIV-1-infected cells to ADCC-mediated killing. This effect will result from the cooperative action of the two moieties of conjugate. The M48U1 moiety will expose the A32-region within the Env trimer which will be subsequently recognized by the A32-region nnAb arm. Aim 1 is designed to develop mAb-M48U1 conjugates using lead mAbs of the A32-region region and evaluate their ability to recognize envelope epitopes and eliminate HIV-1-infected cells through ADCC responses in in vitro and ex-vivo experiments. Aim 2 will evaluate the ability of mAb-M48U1 conjugate to reduce the size of the latent HIV reservoir in ex-vivo “shock and kill” experiments using primary CD4+ T cells from ART-treated and untreated individuals. Pursuing our goal with A32-region conjugates, we expect to diminish the unfavorable impact of HIV-1 Nef- and Vpu-mediated CD4 down regulation that leads to reduction of CD4-inducible ADCC targets on infected cells and fully utilize the potential of nnAbs to kill the HIV-1 infected cells through ADCC. If successful, this project will add new weapons to the arsenal being built to achieve a functional cure in HIV-1- infected individuals.

项目总结/摘要使用消除HIV感染细胞的非中和抗体（nnAb）进行功能性治疗的策略通过Fc受体（FcR）效应器功能，包括抗体依赖性细胞毒性（ADCC），重要的，但在很大程度上尚未开发的研究途径。该项目旨在测试的假设， CD 4模拟微蛋白M48 U1和对第一和第二恒定区中的表位特异的nnAb的缀合物 HIV-1 Env的（C1-C2）区（A32区或A簇表位）将发展成治疗性抗体（tAb）能够有效减少ART感染个体中的感染细胞贮库，从而开发成药剂能够完全通过FcR效应器机制进行功能性治疗。该假设将通过以下方式进行检验：一组抗簇A nnAb，其识别gp 120的高度保守和功能关键区域，提供杀伤的广度，同时使表位逃逸的可能性最小化。我们已经表征了这些表位目标在原子和映射到不连续的网站，涉及高度保守的残基的 g120内域。未配体的Env三聚体中的这些区域对于三聚体稳定性是重要的，在Env刺突与细胞CD 4受体相互作用之前，抗体无法识别。我们最近数据表明，感染细胞上这些靶点的暴露受到低水平的表面CD 4的限制，可以有效地触发细胞表面出现的Env三聚体。这代表了一个高度复杂的艾滋病病毒阻止抗体介导的病毒感染细胞清除的机制。我们能够用CD 4-模拟分子克服这些A32-区表位在感染细胞上的不利暴露，微蛋白M48 U1，其结合在Env三聚体的CD 4结合位点内，并触发它们呈现暴露血清中感染细胞表面A32区表位所需的CD 4结合构象 HIV-1感染者。因此，通过将M48 U1与适当的接头缀合至抗-M48 U1抗体，我们的目标是开发能够使HIV-1感染的细胞对ADCC介导的药物敏感的新tAb。杀人这种效应是由偶联物的两个部分的协同作用引起的。M48 U1部分将暴露Env三聚体内的A32区，其随后将被A32区nnAb臂识别。目的1设计为使用A32区区域的前导mAb开发mAb-M48 U1缀合物，并评估其在体外的生物学活性。它们识别包膜表位并通过ADCC反应消除HIV-1感染细胞的能力，体外和离体实验。目的2将评估mAb-M48 U1缀合物减小细胞内的细胞大小的能力。在使用来自ART处理和未经治疗的个体。追求我们的目标与A32-区域缀合物，我们希望减少不利的 HIV-1 Nef和Vpu介导的CD 4下调导致CD 4诱导的ADCC减少的影响靶向感染细胞，充分利用nnAb通过ADCC杀伤HIV-1感染细胞的潜力。如果如果成功，该项目将为正在建造的武器库增加新的武器，以实现对HIV-1的功能性治疗，感染的人。