Role of Viral Reservoirs in the Pathogenesis of HIV Disease

早在十多年前，我们就证明了在接受临床有效抗逆转录病毒治疗的几乎所有HIV感染者中，静息的CD4+T细胞隔间中潜伏的病毒储存库持续存在。此外，我们还证明，在长期接受抗逆转录病毒治疗的慢性感染者中，艾滋病毒持续以低水平复制。基于上述发现和来自其他群体的类似观察，持续的病毒储存库已成为接受抗逆转录病毒治疗的感染者根除艾滋病毒的主要障碍。因此，目前艾滋病毒治疗研究的一个主要方向是制定战略，以消除艾滋病毒宿主并实现艾滋病毒感染的治愈。考虑到目前在大多数感染者中彻底根除艾滋病毒是不可行的，即使在涉及及早开始治疗的最好情况下，也正在考虑旨在遏制病毒复制的新方法。其目的不一定是实现彻底根除病毒，而是增强艾滋病毒特异性免疫反应或被动转移抗艾滋病毒抗体和其他免疫相关药物，以便在停止抗逆转录病毒治疗后控制血浆病毒血症。 为了解决这个问题，我们最近启动了一项临床试验，题为I期随机、双盲、安慰剂对照研究，通过体内电穿孔递送多抗原DNA疫苗原剂和重组水泡性口炎病毒(RVSV)加强疫苗，用于在急性/早期感染期间开始抗逆转录病毒治疗的HIV感染患者。这是一项随机、双臂(1：1，每臂15名患者)、双盲、安慰剂对照试验，评估HIV多抗原质粒DNA疫苗PRIME与通过电穿孔在体内传递的IL-12质粒DNA佐剂以及在HIV感染急性/早期阶段开始治疗的接受ART的受试者联合使用的安全性和有效性。研究对象在0、4、12和36周随机接种安慰剂或多抗原HIV DNA疫苗，在24周和48周接种rVSV HIV Gag加强疫苗。在第56周的访问后，所有受试者都将接受治疗中断，以确定疫苗接种策略是否导致病毒复制的减少，这是钝化或无反弹的艾滋病毒血浆病毒血症的证据。这项临床试验现已完全纳入。20名研究参与者已经完成了研究的疫苗接种阶段，并停止了抗逆转录病毒治疗。尽管这项研究仍然是盲目的，但我们已经开始对从这些研究对象获得的纵向标本进行广泛的免疫学和病毒学分析。这些分析包括各种实验室分析，旨在测量1)CD4+和CD8+T细胞群体对研究疫苗的免疫反应；2)疫苗接种对CD4+T细胞隔间中持久的HIV储存库的影响以及停止ART后对血浆病毒反弹的影响；以及3)在没有ART的情况下确定病毒学控制的预测因素和相关因素。我们预计所有研究参与者的数据集将于2016年9月完成。 抗体克隆技术的最新进展导致从艾滋病毒感染者的B细胞中发现了一些高度有效和广泛中和艾滋病毒特异性的单抗。在动物模型和少数HIV感染病毒症患者的治疗中断后，已经证明某些广中和HIV特异性抗体可以防止病毒获得，抑制病毒复制，延迟和/或防止血浆病毒反弹。然而，目前尚不清楚这些抗体在停止抗逆转录病毒疗法后对HIV感染者血浆病毒反弹的体内影响。鉴于几乎所有在感染慢性期开始抗逆转录病毒治疗的感染者在停止治疗后都会出现血浆病毒反弹，因此研究有效的HIV特异性单抗(如VRC01)是否可以防止已停止抗逆转录病毒药物的感染者的血浆病毒反弹是非常有意义的。为了解决这个问题，我们启动了一项临床试验，名为VRC01在接受分析治疗中断的慢性艾滋病毒感染患者中的探索性、开放标签研究。这是一项单臂开放研究，旨在检测VRC01对30名HIV感染者的血浆病毒反弹的影响，这些感染者在停止治疗后的慢性感染阶段开始抗逆转录病毒治疗。所有研究参与者在研究的第0、14、28天接受VRC01(40 mg/kg)的输注，此后每月输注VRC01(40 mg/kg)，最长达6个月。所有研究参与者在第3天停止抗逆转录病毒治疗，他们的血浆病毒血症每两周监测一次，以评估VRC01的疗效，这取决于它在停止抗逆转录病毒治疗后对血浆病毒反弹的影响。此外，还将研究研究参与者中耐VRC01艾滋病毒的出现和抗艾滋病毒免疫(即细胞毒性T淋巴细胞反应)发展的动力学。目前共有5名受试者(共30名受试者)进入我们的试验。我们预计这项研究将在2016年3月之前完全纳入研究。

Well over a decade ago, we demonstrated that the latent viral reservoir in the resting CD4+ T cell compartment persists in virtually all HIV-infected individuals receiving clinically effective ART. In addition, we demonstrated that HIV continually replicates at low levels in chronically infected individuals who are consistently aviremic during prolonged periods of receiving ART. Based on the above findings and similar observations from other groups, the persistent viral reservoir has become a major impediment to the eradication of HIV in infected individuals receiving ART. Consequently, a major current thrust of HIV therapeutic research is the development of strategies to eliminate HIV reservoirs and to achieve a cure for HIV infection. Considering that a complete eradication of HIV is not currently feasible in the majority of infected individuals, even under the best of circumstances involving early initiation of therapy, new approaches aimed at containing viral replication are being considered. The aim is not necessarily to achieve complete eradication of the virus, but rather to boost HIV-specific immune responses or passively transfer anti-HIV antibodies and other immune related agents in order to keep plasma viremia in check upon discontinuation of ART. To address this issue, we recently launched a clinical trial entitled a phase I randomized, double-blind, placebo-controlled study of a multi-antigen DNA vaccine prime delivered by in vivo electroporation and a recombinant vesicular stomatitis virus (rVSV) booster vaccine in HIV-infected patients who began antiretroviral therapy during acute/early infection. This is a randomized, 2-arm (1:1, 15 patients per arm), double-blind, placebo-controlled trial evaluating the safety and efficacy of an HIV multi-antigen plasmid DNA vaccine prime, in combination with an interleukin-12 plasmid DNA adjuvant delivered in vivo by electroporation, and a rVSV vaccine boost in subjects receiving ART who initiated therapy during the acute/early phase of HIV infection. Study subjects were randomized to receive placebo or the multi-antigen HIV DNA vaccine at week 0, 4, 12, and 36 and the rVSV HIV gag booster vaccine at week 24 and 48. After the week 56 visit, all subjects will undergo treatment interruption to determine if the vaccination strategy resulted in a reduction of viral replication, as evidenced by blunted or absent rebound HIV plasma viremia. This clinical trial is now fully enrolled. Twenty study participants have already completed the vaccination phase of the study and have discontinued ART. Although the study remains blinded, we have begun extensive immunologic and virologic analyses on longitudinal specimens obtained from these study subjects. These analyses include a variety of laboratory assays that are designed to measure 1) immunologic responses of CD4+ and CD8+ T cell populations to the study vaccines; 2) the impact of vaccination on the persistent HIV reservoir in the CD4+ T cell compartment and on plasma viral rebound upon discontinuation of ART; and 3) identification of predictors and correlates of virologic control in the absence of ART. We expect data sets will be completed on all study participants by September 2016. Recent advances in antibody cloning technologies have led to the discovery of a number of highly potent and broadly neutralizing HIV-specific monoclonal antibodies from B cells of HIV-infected individuals. It has been shown that certain broadly neutralizing HIV-specific antibodies can prevent acquisition of the virus, suppress viral replication, delay and/or prevent plasma viral rebound following treatment interruption in animal models and a small number of HIV-infected viremic individuals. However, it has been unclear what in vivo effects these antibodies might have on plasma viral rebound in HIV-infected individuals following discontinuation of ART. Given that virtually all infected individuals who initiated ART during the chronic phase of infection experience plasma viral rebound upon cessation of therapy, it is of great interest to investigate whether a potent HIV-specific monoclonal antibody, such as VRC01, can prevent plasma viral rebound in infected individuals whose antiretroviral drugs have been discontinued. To address this issue, we have launched a clinical trial entitled an exploratory, open-label study of VRC01 in subjects with chronic HIV infection undergoing analytical treatment interruption. This is a single-arm, open-label study to examine the effect of VRC01 on plasma viral rebound in 30 HIV-infected individuals who initiated ART during the chronic phase of infection following discontinuation of therapy. All study participants receive infusions of VRC01 (40mg/kg) at study days 0, 14, 28, and monthly thereafter for up to 6 months. All study participants discontinue ART on day 3 and their plasma viremia is monitored every 2 weeks to evaluate the efficacy of VRC01 as determined by its effect on plasma viral rebound following discontinuation of ART. Additionally, the kinetics of the emergence of VRC01-resistant HIV and the development of anti-HIV immunity (i.e., cytotoxic T lymphocyte response) in the study participants will be studied. Currently, 5 subjects (total planned accrual of 30 subjects) are enrolled in our trial. We anticipate that the study will be fully enrolled by March 2016.