Using immune complex vaccines to optimize antibody responses to HIV Env

摘要 开发能够诱导多种有效抗体的HIV包膜(Env)免疫原 艾滋病毒-1分离株的分离是艾滋病毒疫苗开发中的一项重大挑战。事实上，促成这一代的因素 具有中和和/或非中和活性的广谱活性抗体尚不清楚。这项提议将 测试抗HIV Env抗体的诱导受形成的抗Env抗体的存在的影响这一概念 免疫复合体(IC)，从而修饰环境抗原表位。具体地说，我们假设 用环状病毒和选择的抗环状病毒单抗(MAbs)制成的免疫疫苗将形成表位 对环境的从头抗体反应的特异性、显性和成熟性。我们早期的研究表明， 抗Env单抗可以用来引导疫苗诱导的内源性抗体反应向或远离某些特定的 包膜抗原表位；这种活性是由mAb良好的特异性决定的。B亚型gp120免疫小鼠的研究 在具有抗CD4结合位点(CD4bs)的复合体中，mAb可激发向V3偏向的高亲和力抗体反应 而用抗V3单抗制成的IC则阻断了V3冠特异性抗体的诱导。相比之下，IC制造 Gp120 CRF01、AEA244和抗V2mAb2158诱导的V1V2抗体应答较高 未复合的A244gp120，以及该IC固有的变构效应，导致与V1V2顶点的较高反应活性- 特异性单抗PG9。值得注意的是，用稳定的环境三聚体(UFO或1KNC)和V2的新结构制成的IC MAB 2158对PG9的反应性也比它们未复杂的同类更强。PG9结合也是 利用抗V2单抗2158和抗V3冠单抗2558的组合在IC形成时增强，从而提供 一种更好地瞄准V1V2顶端同时遮挡V3顶端的策略。这些结果提供了一个令人信服的 进一步评估IC疫苗潜在优势的理论基础。此应用程序建议评估 三聚体Env IC疫苗在兔和恒河猴体内的诱导能力 针对V1V2顶端表位的多功能抗体，并限制对免疫原性V3冠的抗体反应。 为此，在目标1中，我们将初步测试由UFO和1KNC包膜结构物以及V2单抗2158制成的IC疫苗 加/减V3mAb2558，然后向下选择最好的UFO IC和1KNC IC 恒河猴免疫原性研究。疫苗将由IC和UFO Env DNA组成 同时。在目标2中，我们将在猕猴身上比较用F(ab‘)2制成的IC疫苗是否同样有效 作为一种用完整的免疫球蛋白制备的IC，将抗体反应引导到V1V2尖端而远离V3冠状。这 目的评估Fab和Fc对IC免疫调节活性的重要性。将使用具有恒河猴Fc的单抗 在所有的猕猴实验中。最后，目标3将测试UFO DNA和IC联合免疫是否会引发 具有多功能抗病毒活性的ABS可阻断或控制SHV感染。在这项研究完成后，我们 将更好地理解IC疫苗在调节针对HIV Env特定区域的抗体反应方面的效用。这个 这些数据将有助于制定临床适用的战略，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.