Development and In Vivo Characterization of Safety-Enhanced RhCMV/SIV Vectors

安全性增强的 RhCMV/SIV 载体的开发和体内表征

• 批准号: 8227957
• 负责人: Louis J. Picker
• 金额: $ 81.28万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-02-15 至 2016-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8227957
• 关键词: AIDS/HIV problem; Adolescent; Alleles; Antibody Formation; Area; Attenuated; Autopsy; Blood; CD4 Positive T Lymphocytes; CD8B1 gene; Characteristics; Clinical; Coculture Techniques; Cytomegalovirus; Data; Detection; Development; Disease; Dose-Limiting; Engineering; Epidemic; Exhibits; Frequencies; Goals; Growth; HIV; HIV Infections; Human; Immune; Immune response; In Vitro; Individual; Infection; Link; Lymphocyte Depletion; Macaca mulatta; Mediating; Memory; Modeling; Murid herpesvirus 1; Nested PCR; Nucleic Acids; Pathogenicity; Pattern; Phase; Plasma; Population; Pregnant Women; Prevalence; Resistance; SIV; SIV Vaccines; Safety; Site; Southern Africa; T cell response; T memory cell; T-Cell Depletion; T-Lymphocyte; Testing; Time; Tissues; Translations; Vaccinated; Vaccines; Viral; Viremia; Virus; Work; base; combat; design; design and construction; efficacy trial; fetal; immunogenic; immunogenicity; in vivo; nonhuman primate; novel; novel strategies; novel vaccines; prophylactic; public health relevance; rectal; response; vaccine development; vector

DESCRIPTION (provided by applicant): We have demonstrated that CMV/SIV vectors can 1) re-infect CMV+ rhesus macaques (RM), 2) during re-infection, elicit potent and persistent SIV-specific CD4+ and CD8+ T cell responses with a strong "effector memory" (TEM) bias, and 3) completely protect ~50% of vaccinated RM from progressive infection after limiting dose rectal challenge with the highly pathogenic SIVmac239 virus. The protection manifested in these RM is distinct from previous vaccines in its abruptness and extent, with protected RM exhibiting a viral burst in plasma of varying size upon initial infection, followed by immediate control to undetectable levels. Although occasional viral blips in plasma are observed in protected RM, these decline with time, and after 1 year, protection is unaffected by CD8+ or CD4+ cell depletion, and extensive tissue analysis with ultrasensitive nested PCR has shown only rare detection of ~ single copy SIV nucleic acid and no viable SIV. Protection correlates with the total SIV-specific CD8+ TEM generated during the vaccine phase, and occurs without an anamnestic response. These data indicate a novel pattern of protection consistent with very early control, likely taking place at the site of viral entry and/or early sites of viral replication and amplification, and involving tissue-resident CD8+ TEM. Thus, CMV vectors and the "TEM" vaccine concept offer a powerful new approach to HIV/AIDS vaccine development. However, fully replicative CMV vectors are unlikely to be advanced to human use due to the pathogenic potential of CMV. A central goal is therefore to develop CMV vectors that maintain immunogenicity and efficacy, but are safe to use in humans. Fortunately, preliminary data indicates that replication/spread-deficient CMVs can be robustly immunogenic. Here, we will explore the extent to which replication/spread-deficient CMV vectors can be attenuated with respect to pathogenicity and transmissibility, while retaining immunogenicity and efficacy. Three specific aims are proposed: 1) to design, construct and in vitro characterize replication/spread-deficient CMV/SIV vectors, 2) to determine the pathogenicity of replication/spread-deficient CMV/SIV vectors in fetal RM, and 3) to determine the immunogenicity and shedding of replication/spread-deficient CMV/SIV vectors in juvenile RM, and to take the optimal replication/spread deficient vector design to an efficacy trial to determine its ability to protect against limiting dose rectal SIVmac239 challenge. PUBLIC HEALTH RELEVANCE: Worldwide, ~2.5 million new HIV infections occurred in 2007 (with prevalence rates in some areas of southern Africa exceeding 15%), and it is generally agreed that an effective prophylactic vaccine is the only practical means by which the HIV/AIDS epidemic can be controlled. We have demonstrated that cytomegalovirus (CMV) vectors can harness tissue-resident effector memory T cells to combat the AIDS virus very early in infection, and can protect rhesus monkeys from progressive infection after mucosal challenge. The work proposed in this application will enhance the safety of CMV vectors, and provide crucial information for the further clinical development of this novel vaccine approach.

描述（由申请人提供）：我们已经证明 CMV/SIV 载体可以 1) 重新感染 CMV+ 恒河猴 (RM)，2) 在重新感染期间，引发有效且持久的 SIV 特异性 CD4+ 和 CD8+ T 细胞应答，强烈的“效应记忆”(TEM) 偏差，以及 3) 在用高致病性有限剂量直肠攻击后，完全保护约 50% 的接种 RM 免受进行性感染SIVmac239 病毒。这些 RM 所表现出的保护作用在突然性和程度方面与以前的疫苗不同，受保护的 RM 在初次感染时在血浆中表现出不同大小的病毒爆发，随后立即控制到不可检测的水平。尽管在受保护的 RM 中偶尔观察到血浆中的病毒斑点，但这些病毒斑点会随着时间的推移而下降，并且 1 年后，保护不会受到 CD8+ 或 CD4+ 细胞耗竭的影响，并且使用超灵敏巢式 PCR 进行的广泛组织分析显示，仅很少检测到〜单拷贝 SIV核酸，没有活的 SIV。保护作用与疫苗阶段产生的 SIV 特异性 CD8+ TEM 总量相关，并且无需记忆反应即可发生。这些数据表明一种与非常早期控制一致的新型保护模式，可能发生在病毒进入位点和/或病毒复制和扩增的早期位点，并涉及组织驻留的 CD8+ TEM。因此，CMV 载体和“TEM”疫苗概念为 HIV/AIDS 疫苗的开发提供了一种强大的新方法。然而，由于 CMV 的致病潜力，完全复制的 CMV 载体不太可能应用于人类。因此，一个中心目标是开发能够保持免疫原性和功效，但可以安全地用于人类的 CMV 载体。幸运的是，初步数据表明复制/传播缺陷的 CMV 具有很强的免疫原性。在这里，我们将探讨复制/传播缺陷的 CMV 载体的致病性和传播性可在多大程度上减弱，同时保留免疫原性和功效。提出了三个具体目标：1) 设计、构建和体外表征复制/传播缺陷型 CMV/SIV 载体，2) 确定复制/传播缺陷型 CMV/SIV 载体在胎儿 RM 中的致病性，3)确定幼年 RM 中复制/传播缺陷 CMV/SIV 载体的免疫原性和脱落，并将最佳复制/传播缺陷载体设计用于功效试验以确定其能力以防止限制剂量直肠 SIVmac239 挑战。 公共卫生相关性：2007 年，全球新增艾滋病毒感染人数约 250 万（南部非洲某些地区的流行率超过 15%），人们普遍认为，有效的预防性疫苗是预防艾滋病毒/艾滋病的唯一实用手段。艾滋病流行是可以控制的。我们已经证明，巨细胞病毒（CMV）载体可以在感染早期利用组织驻留效应记忆T细胞来对抗艾滋病病毒，并且可以保护恒河猴在粘膜攻击后免受进行性感染。本申请中提出的工作将增强 CMV 载体的安全性，并为这种新型疫苗方法的进一步临床开发提供重要信息。