HIV-1 Neutralizing Antibody Binding to Viral Membrane Mimics

HIV-1 中和抗体与病毒膜模拟物结合

基本信息

批准号：
8525340
负责人：
Stefan Zauscher
金额：
$ 17.74万
依托单位：
DUKE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-08-10 至 2015-07-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Evidence suggests that lipid membrane interactions with rare, broadly neutralizing antibodies (NAbs), 2F5 and 4E10, play a critical role in HIV-1 neutralization. The objective of this proposal is to understand the polyreactivity of NAbs, specifically how lipid membrane properties, such as composition, lipid domain organization, and lipid diffusivity contribute to 2F5/4E10 membrane interactions and antigen localization at the membrane interface, with the ultimate vision of guiding immunogen designs. Recent immunization studies have shown that induction of antibodies that avidly bind the gp41-MPER antigen is not sufficient for neutralization. Rather, it is required that antigen designs induce polyreactive antibodies that can recognize MPER antigens as well as the viral lipid membrane. However, the mechanistic details of how membrane properties influence NAb-lipid and NAb-antigen interactions remain largely unknown. To understand how membrane properties contribute to 2F5/4E10 membrane interactions, we have engineered supported lipid bilayers (SLBs) whose compositions mimic the HIV-1 envelope (Env). We hypothesize that (1) NAbs, 2F5/4E10, and HIV-1 antigen, MPER656, exclusively associate with the most fluid membrane domains. The composition, diffusivity, and surface energies of these domains dictate NAb and antigen interactions with lipid membranes. (2) CDR H3 loops on 2F5 and 4E10 embed selectively into mobile domains on HIV-1 Env mimetic membranes. This ability of CDR H3 loops to anchor into the lipid bilayer gives rise to a preferential antibody binding orientation that reslts in extraction of membrane-submerged antigen residues. To test these hypotheses, we have two specific aims: (SA1) i) Identify the localization of NAbs and antigen on model membrane surfaces. ii) Determine the membrane characteristics that help drive NAb and antigen interactions with lipid domains; i.e., membrane diffusivity, domain composition, and domain surface energies. (SA2) i) Identify binding depth and orientation of 2F5/4E10 on SLBs that mimic mobile domains of HIV-1 lipid Env and ii) identify conformations of NAb-antigen binding at the membrane interface. Our research is significant in that it will reveal molecular details of th role of lipid membranes underlying 2F5/4E10 antigen binding. It is suggested that induction of polyreactive antibodies that can bind to both lipids and MPER antigen is required for neutralization. A recent attempt to use MPER peptide liposomes with only phospholipid components of the host cell membrane failed to induce polyreactive MPER antibodies, although MPER epitope specific antibodies were induced. Importantly, the liposomal design in the above study did not include key anionic lipid components to which 2F5 and 4E10 bind, and also did not include some of the viral lipid components that are abundant on HIV-1 virions. Thus, it is the objective of this proposal to provide information for new immunogen designs that incorporate, in addition to the gp41 MPER epitope, key viral lipid components to which 2F5 and 4E10 bind. The antigen paired with an optimal lipid environment is more likely to induce the required polyreactive antibodies.

描述（由申请人提供）：证据表明，脂质膜与稀有的，广泛中和的抗体（NABS），2f5和4e10的相互作用在HIV-1中和中起着至关重要的作用。该提案的目的是了解NABS的多反应性，特别是脂质膜特性，例如成分，脂质结构域组织和脂质扩散率，有助于2F5/4E10膜相互作用和在膜界面上的抗原位置，并具有最终的视觉效果。引导免疫原设计。最近的免疫研究表明，诱导与GP41-mper抗原的抗体诱导不足以中和。相反，需要抗原设计诱导可以识别MPER抗原以及病毒脂质膜的多反应性抗体。但是，膜特性如何影响NAB-脂质和NAB抗原相互作用的机械细节仍然很大未知。为了了解膜性能如何促进2F5/4E10膜相互作用，我们已经设计了支持的脂质双层（SLB），它们的组成模仿了HIV-1 Invelope（ENV）。我们假设（1）NABS，2F5/4E10和HIV-1抗原，MPER656，仅与最流体的膜结构域相关。这些结构域的组成，扩散性和表面能决定了NAB和抗原相互作用与脂质膜。（2）在2F5和4E10上的CDR H3环选择性地嵌入HIV-1 ENV模拟膜上的移动域。 CDR H3回路锚定入脂质双层的这种能力产生了优先的抗体结合方向，从而在提取膜含有膜的抗原残基中重新提取。为了检验这些假设，我们有两个具体的目的：（SA1）i）确定NAB和抗原在模型膜表面上的定位。 ii）确定有助于驱动NAB和抗原相互作用的膜特性；即，膜扩散率，结构域组成和结构域的表面能。（SA2）i）在模仿HIV-1脂质ENV的移动域和II）上确定2F5/4E10的结合深度和方向，并确定在膜界面上NAB抗原结合的构象。我们的研究很重要，因为它将揭示2F5/4E10抗原结合的脂质膜作用的分子细节。建议中和需要诱导可以与脂质结合和MPER抗原结合的多反应性抗体。尽管诱导了MPER表位特异性抗体，但最近尝试使用仅使用宿主细胞膜磷脂成分的MPER肽脂质体诱导了多反应MPER抗体。重要的是，上述研究中的脂质体设计不包括与2f5和4e10结合的关键阴离子脂质成分，并且还不包括一些在HIV-1病毒体上丰富的病毒脂质成分。因此，该提案的目的是为新的免疫原设计提供信息，除了GP41 MPer表位外，还融合了2F5和4E10结合的GP41 MPer表位。与最佳脂质环境配对的抗原更有可能诱导所需的多反应性抗体。