Harnessing Abs specific for immunogenic and conserved Env epitopes to protect against HIV

项目摘要/摘要 免疫效应器机制提供了对艾滋病毒感染的保护，但仍然知之甚少。 初级/增强ALVAC+gp120蛋白疫苗第三阶段RV144试验的免疫相关性分析， 这使得HIV感染总体减少了31.2%，这表明抗gp120具有保护潜力 抗体反应。具体来说，在RV144病例中评估的6个主要免疫学参数中- 对照研究，对HIV包膜(Env)gp120 V1V2环的高免疫球蛋白应答与 降低感染艾滋病毒的风险。自那以后，这种保护的相关性在SIV/猕猴中得到了概括 模特。此外，在中和抗体水平和环境特异性血浆水平较低的一组疫苗接种者中 免疫球蛋白、对V3环的抗体应答和抗体介导的抗体依赖的细胞毒作用 (ADCC)也与保护有关。然而，目前尚不清楚这些V1V2和V3是否以及如何- 特异性抗体直接介导其保护作用。这些抗体没有广泛的中和作用。 活性，但靶向V1V2和V3环的保守区，并能够介导FC依赖 体外抗病毒作用。针对保守构象表位的非中和抗体也 协同作用，增强ADCC活性。我们在此建议研究保护潜力和 针对V1V2、V3和其他类似免疫原性的保守环境的抗体的作用机制 在人源化小鼠(人源化小鼠)中测试被动注射的人源单抗(MAbs)的表位。 小鼠)模型。拟议的研究是基于我们的初步发现，非中和的V1V2单抗和 弱中和V3单抗均能降低HU-小鼠的病毒感染率和/或病毒载量 植入CD34+的人造血干细胞，并用JRFL HIV-1病毒第二级攻击。 通过接种疫苗可诱导的这些和其他抗环境病毒抗体提供保护的程度 不同的HIV-1毒株尚未确定，其抗病毒机制也尚未确定。 因此，我们建议进行以下实验：首先，评估抗V1V2和抗V3人源单抗对 用HIV-1分离株，特别是传播型/方正毒株攻击HU-小鼠，保护其免受病毒感染 来自B和C亚型的病毒。第二，我们建议测试疫苗诱导的人抗保守型单抗。 利用相同的单抗转移/病毒攻击，在HU-小鼠中表达包膜蛋白V3和恒定区的表位 接近。第三，我们将调查这些单抗在预防艾滋病毒方面的Fab和Fc贡献。至 为此，我们将测量mAb靶向游离病毒粒子和感染细胞的能力，包括体外病毒粒子 以及来自病毒感染的HU-小鼠的细胞。我们还将制备具有Fc突变的单抗，这些单抗可以消除或 增强Fc-受体的相互作用，并测试其保护HU-小鼠免受病毒攻击的能力。来自于此的数据 拟议的研究将帮助我们了解抗体和免疫原性环境抗原表位的类型，由于 它们的保护潜力，应该在未来的艾滋病毒疫苗开发中考虑到。

Project Summary/Abstract Immune effector mechanisms that confer protection against HIV acquisition remain poorly understood. Immune-correlates analysis of the Phase III RV144 trial of the prime/boost ALVAC+gp120 protein vaccine, which delivered an overall 31.2% reduction in HIV acquisition, suggested a protective potential in anti-gp120 antibody responses. Specifically, of the 6 primary immunologic parameters evaluated in the RV144 case- control study, high IgG responses to the V1V2 loop of HIV envelope (Env) gp120 significantly correlated with a reduced risk of HIV acquisition. This correlate of protection has since been recapitulated in the SIV/macaque model. Moreover, in a subset of vaccinees with lower levels of neutralizing antibodies and Env-specific plasma IgA, antibody responses to the V3 loop and antibodies mediating antibody-dependent cellular cytotoxicity (ADCC) were also associated with protection. However, it remains unclear if and how these V1V2- and V3- specific antibodies directly mediate their protective effects. These antibodies have no broad neutralizing activity, but target conserved regions of the V1V2 and V3 loops and are capable of mediating Fc-dependent antiviral functions in vitro. Nonneutralizing antibodies against conserved conformational epitopes also synergize to enhance ADCC activity. We propose herein to investigate the protective potential and mechanisms of action of antibodies targeting V1V2, V3, and other, similarly immunogenic, conserved Env epitopes by testing passively administered human monoclonal antibodies (mAbs) in a humanized mouse (hu- mice) model. The proposed study is based on our preliminary findings that a nonneutralizing V1V2 mAb and a weakly neutralizing V3 mAb were each able to reduce virus infection rate and/or virus burden in hu-mice that were engrafted with CD34+ human hematopoietic stem cells and challenged with a tier 2 JRFL HIV-1 virus. The extent to which these and other anti-Env antibodies inducible by vaccination confer protection against diverse HIV-1 strains has not been determined, and their antiviral mechanisms also have not been defined. Therefore, we propose experiments to, first, evaluate the ability of anti-V1V2 and anti-V3 human mAbs to protect against virus infection in hu-mice upon challenge with HIV-1 isolates, particularly transmitted/founder viruses from subtypes B and C. Second, we propose testing vaccine-induced human mAbs against conserved epitopes in the V3 and constant regions of Env in hu-mice, using the same mAb transfer/virus challenge approach. Third, we will investigate the Fab and Fc contributions of these mAbs in protection against HIV. To this end, we will measure the mAb capacity to target free virions and infected cells, including ex vivo virions and cells from virus-infected hu-mice, in vitro. We will also prepare mAbs with Fc mutations that abrogate or enhance Fc-receptor interactions and test their ability to protect hu-mice against virus challenge. Data from this proposed study will help us understand the types of antibodies and immunogenic Env epitopes that, due to their protective potential, should be considered in future HIV vaccine development.