Using immune complex vaccines to optimize antibody responses to HIV Env

摘要 开发HIV包膜（Env）免疫原，能够引发有效对抗多种 HIV-1分离株的分离是HIV疫苗开发中的主要挑战。事实上，促成这一代人的因素 具有中和和/或非中和活性的广泛反应性Ab的存在尚不清楚。这项建议会 测试抗HIV Env抗体的诱导受抗Env抗体存在的影响这一概念， 免疫复合物（IC）和因此修饰Env上表位。具体来说，我们假设， 施用由Env和选择的抗Env单克隆抗体（mAb）制成的IC疫苗将形成表位 特异性、优势和对Env的从头Ab应答的成熟。我们早期的研究表明， 抗Env单克隆抗体可用于引导疫苗诱导的内源性抗体应答朝向或远离某些免疫原。 Env表位;该活性由mAb的精细特异性决定。用B亚型gp 120免疫小鼠 与抗CD 4结合位点（CD 4 bs）mAb复合后，引起高亲和力Ab应答，偏向V3 冠，而IC与抗V3单克隆抗体阻断诱导V3冠特异性抗体。相比之下， gp 120 CRF01.AE A244和抗V2 mAb 2158诱导的对V1 V2的Ab应答高于 未复合的A244 gp 120，该IC固有的变构效应导致与V1 V2顶点的更高反应性。 特异性mAb PG 9。值得注意的是，用稳定的Env三聚体（UFO或1 KNC）和V2的新构建体制备的IC mAb 2158与PG 9的反应性类似地高于其未复合的对应物。PG 9结合也是 抗V2 mAb 2158和抗V3冠状mAb 2558的组合增强IC形成，从而提供 在封堵V3牙冠的同时更好地瞄准V1 V2心尖的策略。这些结果提供了令人信服的 进一步评价IC疫苗潜在优势的理由。本申请旨在评估 三聚体Env IC疫苗在兔和恒河猴中增强 针对V1 V2顶点中的表位的多功能Ab和限制对免疫原性V3冠的Ab应答。 为此，在目标1中，我们将首先测试由UFO和1 KNC Env构建体和V2 mAb 2158制成的IC疫苗 加/减V3 mAb 2558，然后向下选择最佳UFO IC和最佳1 KNC IC。 恒河猴免疫原性研究。这些疫苗将包括IC和UFO Env DNA， 同步在目标2中，我们将在猕猴中比较用F（ab '）2制备的IC疫苗是否同样有效 作为用完整IgG制备的IC，将Ab应答引导至V1 V2顶点并远离V3冠。这 目的是评估Fab与Fc对IC免疫调节活性的重要性。将使用含恒河猴Fc的mAb 在所有的猕猴实验中。最后，目标3将测试是否与UFO DNA和IC的共同免疫， 具有多功能抗病毒活性的抗体可以阻断或控制SHIV感染。在本研究结束时，我们 将更好地了解IC疫苗调节针对HIV Env特定区域的Ab应答的效用。的 这些数据将有助于制定临床适用的策略，以生产有效的艾滋病毒疫苗。

Abstract Developing HIV envelope (Env) immunogens capable of eliciting antibodies (Abs) effective against a broad array of HIV-1 isolates is a major challenge in HIV vaccine development. Indeed, factors contributing to the generation of broadly reactive Abs with neutralizing and/or nonneutralizing activities are not understood. This proposal will test the concept that induction of Abs against HIV Env is influenced by the presence of anti-Env Abs that form immune complexes (ICs) and that consequently modify epitopes on Env. Specifically, we hypothesize that administration of an IC vaccine made of Env and select anti-Env monoclonal Ab (mAbs) will shape epitope specificity, dominance, and maturation of de novo Ab responses to Env. Our earlier studies have shown that anti-Env mAbs can be used to direct vaccine-induced endogenous Ab responses toward or away from certain Env epitopes; this activity is dictated by the mAb's fine specificity. Immunization of mice with subtype B gp120 in complex with an anti-CD4-binding site (CD4bs) mAb elicited high-affinity Ab responses skewed toward the V3 crown, while an IC made with an anti-V3 mAb blocked induction of V3 crown-specific Abs. In contrast, IC made of gp120 CRF01.AE A244 and anti-V2 mAb 2158 induced a higher Ab response to V1V2 compared to uncomplexed A244 gp120, and allosteric effects inherent to this IC resulted in higher reactivity with V1V2 apex- specific mAb PG9. Of note, ICs made with novel constructs of stabilized Env trimers (UFO or 1KNC) and V2 mAb 2158 were similarly more reactive with PG9 than their uncomplexed counterparts. PG9 binding was also enhanced upon IC formation with a combination of anti-V2 mAb 2158 and anti-V3 crown mAb 2558, thus offering a strategy to better target the V1V2 apex while occluding the V3 crown. These results provide a compelling rationale for further evaluation of the potential advantages of IC vaccines. This application proposes to evaluate trimeric Env IC vaccines in rabbits and rhesus macaques for the capacity to augment the induction of multifunctional Abs against epitopes in the V1V2 apex and to limit Ab responses to the immunogenic V3 crown. To this end, in Aim 1, we will initially test IC vaccines made of UFO and 1KNC Env constructs and V2 mAb 2158 plus/minus V3 mAb 2558 in rabbits, followed by down selection of the best UFO IC and the best 1KNC IC in rhesus macaque immunogenicity studies. The vaccines will comprise of ICs and UFO Env DNA delivered simultaneously. In Aim 2, we will compare in macaques whether an IC vaccine made with F(ab')2 is as effective as an IC made with intact IgG in directing Ab responses to the V1V2 apex and away from the V3 crown. This aim will assess the importance of Fab vs Fc to IC immunomodulatory activity. mAbs with rhesus Fc will be used in all macaque experiments. Finally, Aim 3 will test whether co-immunization with UFO DNA and IC that elicits Abs with polyfunctional antiviral activities can block or control SHIV infection. At the completion of this study, we will better understand the utility of IC vaccines to modulate Ab response against specific regions of HIV Env. The data will be useful in developing a clinically applicable strategy to produce effective HIV vaccines.