Suppressing the latent reservoir with a Tat inhibitor

 描述：尽管抗逆转录病毒疗法(ART)在将艾滋病毒复制减少到非常低的水平方面取得了巨大的成功，但它未能根除病毒。在接受ART抑制治疗的个体中，HIV-1仍然持续存在于潜伏作用的记忆中的CD4+T细胞中，这些细胞代表着ART中断后复活病毒的长期来源。最常探索的根除艾滋病毒的策略被称为“休克并杀死”，它试图使用HDAC抑制剂等抗潜伏剂清除病毒库，同时通过维持抗逆转录病毒治疗来防止更多轮感染。已经采用了其他几种策略来根除潜伏的HIV-1储存库，包括强化抗逆转录病毒疗法、治疗性疫苗、基因疗法和干细胞移植。每一种方法都有其固有的挑战，没有一种方法显示出绝对的成功。另一种方法是使用针对HIV-1转录的治疗剂，这与根除潜伏宿主的既定范例有很大不同。我们不是激活内源潜伏库，而是将ART过程中发生的残余转录驱动到长期潜伏期或深潜伏期状态。我们基于最近的发现，二氢皮质抑素A(DCA)，一种从海绵中分离出来的天然化合物的类似物，在纳摩尔浓度下有效地抑制TAT介导的整合HIV-1启动子的反式激活。重要的是，DCA在体外使病毒基因表达进入一种持续的深潜伏期诱导状态，难以被病毒重新激活。TAT抑制剂联合ART治疗的目的是通过阻止正在进行的病毒复制、重新激活和补充潜伏病毒储存库来缩小潜伏储存池的大小，这是当前ART的一个关键限制。在这里，我们建议在感染猴免疫缺陷病毒(SIV)的恒河猴身上检测DCA。我们假设，通过减少持续的、低水平的病毒从储存库中产生，DCA将i)通过阻止其持续补充来减少病毒储存库的大小，ii)防止或至少显著延迟ART停止后的病毒反弹，以及iii)减少与抑制ART受试者的低水平病毒复制所引起的持续水平的免疫激活相关的发病率。在R21项目阶段，我们将验证DCA可以有效地阻断原始恒河猴CD4+淋巴细胞中SIV的转录。在成功完成R21里程碑后，我们将启动项目的R33阶段，旨在确定将DCA与ART结合的影响，以及一旦病毒转录抑制，DCA是否可以取代ART。

 DESCRIPTION: Despite the immense success of anti-retroviral therapy (ART) in reducing HIV replication to very low levels, it fails to eradicate the virus. HIV-1 still persists in latently ifected memory CD4+ T cells in individuals on suppressive ART and these cells represent a long-lasting source of resurgent virus upon ART interruption. The most commonly explored strategy for HIV eradication is dubbed "shock and kill", which attempts to purge viral reservoirs using anti-latency agents such as HDAC inhibitors, while simultaneously preventing additional rounds of infection by maintaining ART. Several other strategies have been employed for eradicating the latent HIV-1 reservoir including ART intensification, therapeutic vaccines, gene therapy, and stem cell transplantation. Each approach has its own inherent challenges and none have demonstrated definitive success. An alternative approach, which represents a significant departure from established paradigms of eradicating latent reservoirs, uses therapeutic agents targeting HIV-1 transcription. Rather than activating the endogenous latent reservoir, we propose to drive the residual transcription that occurs during ART into a state of long-term latency or deep latency. We based this proposal on the recent discovery that didehydro-Cortistatin A (dCA), an analog of a natural compound isolated from a marine sponge, potently inhibits Tat-mediated trans-activation of the integrated HIV-1 promoter at nanomolar concentrations. Importantly, dCA drives viral gene expression into an induced state of persistent deep-latency in vitro, refractory to viral reactivation. A Tat-inhibitor treatment combined with ART would be aimed at reducing the size of the latent reservoir pool by blocking ongoing viral replication, reactivation and replenishment of the latent viral reservoir, a key limitation of currnt ART. Here we propose to test dCA in rhesus macaques infected with simian immunodeficiency virus (SIV). We hypothesize that by reducing persistent, low-level virus production from reservoirs, dCA will i) reduce the size of the viral reservoir by preventing its continued replenishment, ii) prevent or at least significantly delay viral rebound upon ART discontinuation, and iii) reduce morbidities associated with persistent levels of immune activation caused by low-levels of virus replication in subjects on suppressive ART. During the R21 project phase we will validate that dCA can be efficiently used to block SIV transcription in primary rhesus macaque CD4+ lymphocytes. Upon successful accomplishment of R21 milestones, we will initiate the R33 phase of the project, which is aimed at determining the impact of combining dCA with ART, and whether dCA may replace ART once virus is transcriptionally suppressed.