Overcoming pre-existing immunity to AAV to enhance AAV-based HIV immunotherapies

项目摘要 腺相关病毒（AAV）介导的具有广泛（B）中和（n）抗体（Abs）的基因治疗 为预防和治疗艾滋病毒感染带来了巨大希望。这种方法是独特的，因为宿主细胞， 通过AAV转导接受相关基因后，可立即开始分泌bnAb进入 流通因为AAV是非致病性的并且其基因组在宿主细胞中持续存在，所以成功的AAV转导是不可能的。 长寿命细胞，如肌肉细胞，可以导致bnAbs持续表达多年， 几十年因为在人类身上实现这一愿景将大大简化与艾滋病毒/艾滋病作斗争的努力， 大流行，该项目的重点是克服AAV/bnAb治疗的临床使用的一个关键障碍： 抗AAV nAb在人类中的流行率。抗AAV nAb靶向AAV衣壳，并且主要由天然抗体诱导。 感染野生型（WT）AAV，其在灵长类动物中流行。AAV血清阳性率在地理上不同， 范围为30%至100%，取决于AAV血清型。由于不同的结构之间的相似性 在衣壳中，由WT AAV感染诱导的nAb经常与其他AAV血清型交叉反应，包括使用的那些 基因治疗这是有问题的，因为取决于nAb滴度，Ab介导的AAV中和是不可能的。 载体可以减少或甚至消除转导。因此，目前排除AAV血清阳性（+）个体 从基于AAV的基因疗法的临床试验中。这些观察，在3800万的背景下， 世界各地的艾滋病毒感染者（PLWH）谁可以从AAV/bnAb治疗中受益，强调需要开发 克服预先存在的抗AAV nAb的策略。在这里，我们提出了一系列的方法来绕过体液 在AAV（+）个体中对AAV的免疫力，最终目标是扩大人们获得AAV/bnAb治疗的机会。 该项目有四个具体目标。我们的第一个目标是确定亚细胞中最不常见的亲肌性AAV衣壳， 撒哈拉非洲，三分之二的艾滋病毒携带者的家园。从该血清调查中获得的知识将允许AAV（-） PLWH将受益于AV/bnAb疗法，无需任何额外干预。Aim 1还将确定范围 必须克服预先存在的抗AAV nAb滴度，以使AAV在田间环境中转导。我们的第二 第三个目的是评估血清IgG Ab的瞬时消耗可以减少抗AAV nAb的程度， AAV（+）恒河猴（RM）中的滴度。我们的最终目标是通过检验是否 在RM中耗尽预先存在的抗-AAV nAb，其中RM具有病毒控制的猿猴免疫缺陷病毒 (SIV)感染可增强AAV介导eCD 4-Ig-a bnAb样分子的递送， 艾滋病毒和SIV。目的4还将评估AAV表达的eCD 4-IG维持抗逆转录病毒疗法的能力。 自由控制SIV病毒复制。因此，该项目不仅将建立一个测试基于无人驾驶飞机的蓝图， 艾滋病毒免疫疗法在艾滋病毒/艾滋病流行病的中心，但它也将扩大我们的工具包， 干预以避免对AAV的预先存在的免疫。如果成功，这项研究可以使我们更接近 在人中实现持续的AAV驱动的抗HIV生物制剂的生产，而不管AAV血清状态如何。

PROJECT SUMMARY Adeno-associated virus (AAV)-mediated gene therapy with broadly (b) neutralizing (n) antibodies (Abs) holds great promise for preventing and treating HIV infection. This approach is unique in that host cells, after receiving the relevant genes through AAV transduction, can immediately begin to secrete bnAbs into the circulation. Because AAV is non-pathogenic and its genome persists in host cells, successful AAV transduction of long-lived cells, such as muscle cells, can result in continuous expression of bnAbs for years, possibly decades. Since realizing this vision in humans would dramatically simplify efforts to combat the HIV/AIDS pandemic, this project focuses on overcoming a key obstacle to the clinical use of AAV/bnAb therapy: the high prevalence of anti-AAV nAbs in humans. Anti-AAV nAbs target the AAV capsid and are mainly induced by natural infection with wild-type (WT) AAV, which is endemic in primates. AAV seroprevalence varies geographically, ranging from 30% to 100%, depending on the AAV serotype. Because of structural similarities among different capsids, nAbs induced by infection with WT AAV often cross-react with other AAV serotypes, including those used for gene therapy. This is problematic because, depending on the nAb titer, Ab-mediated neutralization of AAV vectors can reduce or even abrogate transduction. Hence, AAV seropositive (+) individuals are currently excluded from clinical trials of AAV-based gene therapies. These observations, viewed in the context of the 38 million people living with HIV (PLWH) worldwide who could benefit from AAV/bnAb therapy, highlight the need to develop strategies to overcome pre-existing anti-AAV nAbs. Here we propose a series of approaches to bypass humoral immunity to AAV in AAV(+) individuals, with the ultimate goal of expanding people’s access to AAV/bnAb therapy. This project has four specific aims. Our first aim is to identify the least prevalent muscle-tropic AAV capsid in sub- Saharan Africa, home of two thirds of all PLWH. Knowledge gained from this serosurvey would allow AAV(–) PLWH to benefit from AAV/bnAb therapies without any additional intervention. Aim 1 will also establish the range of pre-existing anti-AAV nAb titers that must be overcome to enable AAV transduction in field settings. Our second and third aims are to assess the extent to which transient depletion of serum IgG Abs can decrease anti-AAV nAb titers in AAV(+) rhesus macaques (RMs). Our final aim is to integrate the findings of Aims 1-3 by testing whether depleting pre-existing anti-AAV nAbs in RMs with pharmacologically controlled simian immunodeficiency virus (SIV) infection can enhance AAV-mediated delivery of eCD4-Ig–a bnAb-like molecule that potently neutralizes both HIV and SIV. Aim 4 will also assess the ability of AAV-expressed eCD4-Ig to maintain antiretroviral therapy- free control of SIV virus replication. Thus, this project will not only establish a blueprint for testing AAV-based HIV immunotherapies in the epicenter of the HIV/AIDS pandemic, but it will also expand our toolkit of interventions for evading pre-existing immunity to AAV. If successful, this research could bring us closer to achieving sustained AAV-driven production of anti-HIV biologics in people, regardless of AAV serostatus.