Project 1: Immunologic and Virologic Characterization of RhCMV/SIV Vaccine-Mediated SIV Replication Arrest Efficacy

项目1 -项目概要 基于表达SIV抗原的恒河猴巨细胞病毒68-1株的HIV临床前疫苗研究 （RhCMV/SIV）增强细胞免疫应答，严格阻止原发性SIV的复制和传播 59%的接种疫苗的恒河猴（RM）感染。绝大多数疫苗保护的RM将 维持这种SIV复制停滞（组织中具有复制能力的SIV的一种病毒血症状态）， 在随后的1-3年内腐烂或灭绝。这种免疫介导的病毒 抑制没有先例，尽管精确的病毒学和免疫学机制 这一现象的基础仍然未知，我们已经确定，（a）复制抑制功效取决于 对RhCMV/SIV诱导靶向SIV肽的SIV特异性CD 8 + T细胞的作用 组织相容性复合物（MHC）-E而不是MHC-II或常规MHC-Ia，和（B）在具有 MHC-E限制性CD 8 + T细胞应答，通过持续的全血转录组学预测疗效。 特征在于IL-15信号传导。这些数据表明，先天免疫/IL-15信号促进，MHC- E-限制性SIV特异性CD 8 + T细胞应答介导/协调复制阻滞功效， 作为这种模式功效基础的体内功能输出对于这种响应是独特的，因此不同于 其他类型的SIV特异性CD 8 + T细胞应答的功能输出。这反过来又表明， 有效应答与其他疫苗诱导的CD 8 + T细胞应答类型的功能比较， 介导复制抑制功效（包括通过程序化的MHC-Ia-和MHC-II-限制性应答）， 通过常规初免-加强免疫接种的RhCMV/SIV和MHC-Ia限制性应答）将阐明 这些差异是复制停滞结果的基础。因此，在S.A.1中，我们将利用T细胞受体（TCR）- 索引的单细胞转录组学，以确定区分这些SIV的细胞内在转录模式， 疫苗后期的特异性CD 8 + T细胞反应，重要的是。与随后的SIV激发相关 结果（复制停滞vs.进行性感染）。在S.A.2中，我们将对早期复制进行病毒学表征 阻滞，确定残留SIV的组织范围、细胞分布和状态（转录，翻译， 在尸检时，68-1 RhCMV/SIV载体保护的RM中的病毒体产生）。我们的目标是定义网站， 宿主细胞复制停滞以及是否涉及抑制SIV基因表达和病毒体产生 （类似于深潜伏期）和/或对靶细胞的作用，使它们对病毒感染具有抗性。最后在 S.A.3，我们将表征对被抑制的SIV的细胞应答（CD 8 + T细胞和辅助细胞类型 在尸检中通过本体和单细胞转录组学和空间分析在RhCMV/SIV保护的RM中复制 组织中这些研究的成功完成将使我们进一步了解所提供的独特保护 并促进基于CMV的载体成功临床转化用于预防性HIV疫苗。

PROJECT 1 - PROJECT SUMMARY A pre-clinical HIV vaccine approach based on strain 68-1 of rhesus cytomegalovirus expressing SIV antigens (RhCMV/SIV) elicits cellular immune responses that stringently arrest replication and spread of primary SIV infection in 59% of vaccinated rhesus macaques (RMs). The vast majority of these vaccine-protected RMs will maintain this SIV replication arrest (a state of aviremia with replication-competent SIV in tissues) until virus decays or is cleared to extinction over the subsequent 1-3 years. This pattern of immune-mediated viral suppression has no prior precedent and although the precise virologic and immunological mechanisms underpinning this phenomenon remain unknown, we have established that (a) replication arrest efficacy depends on RhCMV/SIV elicitation of SIV-specific CD8+ T cells that target SIV peptides in the context of major histocompatibility complex (MHC)-E rather than MHC-II or conventional MHC-Ia, and (b) that among RMs with MHC-E-restricted CD8+ T cell responses, efficacy is predicted by a sustained whole blood transcriptomic signature featuring IL-15 signaling. These data suggest that an innate immune/IL-15 signaling-facilitated, MHC- E-restricted, SIV-specific CD8+ T cell response mediates/coordinate replication arrest efficacy and that the in vivo functional outputs underlying this pattern efficacy are unique to this response and thus different from functional outputs of other types of SIV-specific CD8+ T cell responses. This, in turn, suggests that detailed functional comparison of the effective responses with other vaccine-elicited CD8+ T cell response types that fail to mediate replication arrest efficacy (including MHC-Ia- and MHC-II-restricted responses by programmed RhCMV/SIV and MHC-Ia-restricted responses by conventional prime-boost vaccination) will elucidate differences that underlie the replication arrest outcome. Thus, in S.A.1 we will utilize T cell receptor (TCR)- indexed single cell transcriptomics to identify cell-intrinsic transcriptional patterns that distinguish these SIV- specific CD8+ T cell responses in late vaccine phase and, importantly. correlate with subsequent SIV challenge outcome (replication arrest vs. progressive infection). In S.A.2, we will virologically characterize early replication arrest, determining the tissue extent, cellular distribution and state of residual SIV (transcription, translation, virion production) among 68-1 RhCMV/SIV vector-protected RM at necropsy. Our goal is to define the sites and cells hosting replication arrest and whether it involves suppression of SIV gene expression and virion production (analogous to deep latency) and/or an effect on target cells, rendering them resistant to viral infection. Finally, in S.A.3, we will characterize the cellular response (both CD8+ T cells and accessory cell types) to arrested SIV replication in RhCMV/SIV-protected RMs via bulk and single cell transcriptomics and spatial profiling in necropsy tissues. Successful completion of these studies will further our understanding of the unique protection afforded by CMV vectors and facilitate successful clinical translation of CMV-based vectors for a prophylactic HIV vaccine.