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

项目1--项目总结 表达SIV抗原的恒河猴巨细胞病毒68-1株HIV疫苗的临床前研究 (RhCMV/SIV)诱导细胞免疫反应，严格阻止原发SIV的复制和传播 59%接种疫苗的恒河猴(RMS)感染。这些疫苗保护的RMS中的绝大多数将 保持这种SIV复制停止(组织中具有复制能力的SIV的无血症状态)，直到病毒 在接下来的1-3年里腐烂或被清除到灭绝。这种免疫介导的病毒模式 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)复制抑制效果取决于 重组人巨细胞病毒/SIV对SIV特异性CD8+T细胞的诱导作用 组织相容性复合体(MHC)-E而不是MHC-II或常规MHC-Ia，以及(B)RMS与 MHC-E限制的CD8+T细胞反应，通过持续的全血转录预测疗效 带有IL-15信号的签名。这些数据表明，一种先天免疫/IL-15信号促进的MHC- E-限制性、SIV特异性CD8+T细胞应答介导/协调复制抑制效应 这种模式功效背后的活体功能输出对于这种反应是独一无二的，因此不同于 其他类型的SIV特异性CD8+T细胞反应的功能输出。这反过来又表明，详细的 有效应答与其他疫苗诱导的失败CD8+T细胞应答类型的功能比较 介导复制抑制效应(包括MHC-Ia和MHC-II通过编程的限制性反应 RhCMV/SIV和MHC-Ia对传统加强免疫的限制性反应)将阐明 作为复制阻止结果的基础的差异。因此，在S.A.1中，我们将利用T细胞受体(TCR)- 编入索引的单细胞转录切片，以确定区分这些SIV- 疫苗后期的特异性CD8+T细胞反应，更重要的是。与后续SIV挑战相关 结果(复制停止与进行性感染相比)。在S.A.2中，我们将对早期复制进行病毒学表征 阻断，确定残留SIV的组织范围、细胞分布和状态(转录、翻译、 在68-1RhCMV/SIV载体保护的rM中)。我们的目标是定义地点和 宿主复制停滞的细胞及其是否涉及SIV基因表达和病毒粒子产生的抑制 (类似于深度潜伏期)和/或对目标细胞的影响，使其对病毒感染具有抵抗力。最后，在 S.A.3，我们将表征细胞(CD8+T细胞和辅助细胞类型)对受阻SIV的反应 在尸检中通过批量和单细胞转录和空间图谱在RhCMV/SIV保护的RMS中复制 纸巾。成功完成这些研究将进一步加深我们对所提供的独特保护的理解 通过CMV载体，并促进基于CMV的预防性HIV疫苗载体的临床成功翻译。

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.