Development of Immunogenicity- and Efficacy-Optimized CMV Vectors for an HIV/AIDS Vaccine

总体计划摘要 十多年前，我们团队开始了基于持久性β的疫苗载体的开发- 疱疹病毒巨细胞病毒(CMV)由于具有诱导和无限期维持高水平的能力 不同组织中频率效应器分化的T细胞反应。使用恒河猴(RM)模型， 我们测试了这样一个概念，即早期的病原体拦截是由这种“就地”效应-记忆T细胞提供的 将导致对免疫逃避病原体(如艾滋病毒/SIV)的更好保护，相对于典型的 传统疫苗方法引起的记忆反应。我们发现，不仅莱瑟斯(Rh) CMV易于“矢量化”(例如，我们证明，即使在传播不足的情况下，RhCMV载体也是如此 在天然RhCMV+细胞中产生有效、持久、外源性插入特异性效应记忆T细胞反应 Rm)，而且由这些载体引起的SIV特异性应答能够重复性地严格地 对照，然后清除粘膜注射的高致病性SIV，从大约54%的疫苗接种RM。虽然 这种史无前例的“控制和明确”保护与早期的感染拦截是一致的，其性质是 保护性免疫反应一直难以捉摸，直到我们发现Rh157.5/Rh157.4基因缺失 作为我们疫苗骨架的RhCMV载体还有另一个非常不寻常的免疫学特性：全CD8+ 发现由该载体诱导的T细胞识别受MHC-II或MHC-E限制的表位， 不是MHC-Ia。我们进一步证明，这种非常规的表位靶向被恢复为常规的 通过修复Rh157.5/Rh157.4的表达来限制MHC-Ia的表达，否则不影响功能或 载体诱导的CD8+T细胞的表型特征。值得注意的是，修复的RhCMV/SIV载体失败了 为抵御SIV挑战，强烈建议非常规CD8+T细胞表位识别 RCMV/SIV载体效力所必需的。最近的研究表明，传统与非传统 CD8+T细胞的启动受多个RhCMV基因的调控，这些基因的修饰有效地编程 利用不同的表位识别模式诱导CD8+T细胞应答。在这个节目中，我们 首先试图确定非常规CD8+T细胞反应产生的机制，以及 开发主要或唯一诱导MHC-II或MHC-E限制性CD8+T细胞的RhCMV载体 答复(项目2-4)。然后，我们将使用这些新向量来1)确定所需的响应类型(S) 有效性，2)确定这种响应聚焦是否提高了有效性，以及3)定义了定量和/或 这一保护的质的相关性(项目1)。最后，我们将使用在这些RM研究中获得的见解 设计(项目4)、制造和临床测试(项目5)喷雾剂的安全性和免疫原性- 缺陷的、“反应程序化”的人类巨细胞病毒/艾滋病毒载体，旨在诱导保护性反应类型。如果这个 如果努力取得成功，结果将是一种高度有效的艾滋病毒/艾滋病疫苗，无论是单独接种，还是与 补充性抗体靶向疫苗可大大有助于结束艾滋病毒/艾滋病的流行。

Overall Program Summary More than a decade ago our group initiated development of vaccine vectors based on the persistent β- herpesvirus Cytomegalovirus (CMV) because of the ability of CMV to elicit and indefinitely maintain high frequency effector-differentiated T cell responses in diverse tissues. Using the rhesus macaque (RM) model, we tested the concept that the early pathogen intercept afforded by such “in place” effector-memory T cells would result in superior protection against immune evasive pathogens like HIV/SIV, relative to the typical memory responses elicited by conventional vaccine approaches. We found that not only was Rhesus (Rh) CMV amenable to “vectorization” (e.g., we demonstrated that, even when spread-deficient, RhCMV vectors generate potent, durable, exogenous insert-specific effector-memory T cell responses in naturally RhCMV+ RM), but also that the SIV-specific responses elicited by these vectors were reproducibly able to stringently control and then clear mucosally-administered, highly pathogenic SIV from ~54% of vaccinated RM. Although this unprecedented “control and clear” protection was consistent with an early infection intercept, the nature of the protective immune response remained elusive until we discovered that the Rh157.5/Rh157.4 gene-deleted RhCMV vector used as the backbone of our vaccine had another very unusual immunologic property: all CD8+ T cell elicited by this vector were found to recognize epitopes that were restricted by either MHC-II or MHC-E, not MHC-Ia. We further demonstrated that this unconventional epitope targeting was reverted to conventional MHC-Ia restriction by repair of Rh157.5/Rh157.4 expression, which did not otherwise affect the functional or phenotypic characteristics of vector-elicited CD8+ T cells. Remarkably, the repaired RhCMV/SIV vectors failed to protect against SIV challenge, strongly suggesting that unconventional CD8+ T cell epitope recognition is required for RCMV/SIV vector efficacy. Recent work has demonstrated that conventional vs. unconventional CD8+ T cell priming is regulated by multiple RhCMV genes, the modification of which effectively programs RhCMV vectors to elicit CD8+ T cell responses with distinct epitope recognition patterns. In this program, we first seek to determine the mechanisms responsible for unconventional CD8+ T cell response generation, and develop RhCMV vectors that predominantly or exclusively elicit MHC-II vs. MHC-E-restricted CD8+ T cell responses (Projects 2-4). We will then use these new vectors to 1) identify the response type(s) needed for efficacy, 2) determine whether such response focusing improves efficacy, and 3) define quantitative and/or qualitative correlates of this protection (Project 1). Finally, we will use the insight gained in these RM studies to design (Project 4), manufacture and clinically test (Project 5) the safety and immunogenicity of a spread- deficient, “response-programmed” HCMV/HIV vector designed to elicit the protective response type. If this effort is successful, the result would be a highly effective HIV/AIDS vaccine that alone, or combined with a complementary antibody-targeted vaccine, could substantially contribute to ending the HIV/AIDS epidemic.