Project 2: Characterization of the in vivo T cell (and overall immune) interception of primary SIV infection after vaccination with differentially response programmed RhCMV/SIV vectors

项目2 -项目概要 用表达SIV插入片段的68-1恒河猴巨细胞病毒载体接种恒河猴（RM） （RhCMV/SIV）增强免疫应答，59%的疫苗接种者可以拦截并有效地阻止早期免疫应答。 主要传播SIV感染。这种独特的“复制抑制”功效模式与三种68- 1. RhCMV/SIV免疫特性，包括其产生和维持的能力：1）高量级， 循环和基于组织的效应记忆偏向性CD 8 + T细胞应答，2）主要组织相容性复合体 （3）在具有MHC-E限制性CD 8 + T细胞的RM中， 免疫应答，一种对疫苗接种的保护预测性先天免疫转录应答，包括中枢免疫应答。 IL-15信号传导成分;然而，复制阻滞保护的特定免疫机制 是未知的。RhCMV/SIV载体现在可以通过遗传操作进行编程，以诱导SIV特异性CD 8 + T细胞应答仅受MHC-E-、MHC-II-和MHC-Ia-限制，而后者2 反应类型在幅度和表型上与MHC-E限制性反应相似，它们以及 传统的初免-加强疫苗引起MHC-Ia限制性CD 8 + T细胞应答，不能介导SIV 复制停滞这表明保护性（IL-15/先天调节的）MHC-E限制性SIV特异性CD 8 + T细胞亚群在SIV特异性CD 8 + T细胞亚群中起作用。 T细胞在拦截原发性SIV感染时必须表现出与其他T细胞不同的反应。 应答类型，可能在体内检测和应答SIV感染的细胞方面更有效，和/或 在被感染的细胞识别时表现出不同的（更有效的）功能程序。在这个项目中，我们将 使用复杂的“组学”技术，能够详细描述组织免疫反应 （包括T细胞受体定义的、SIV特异性CD 8 + T细胞的特异性分析）来定义这些差异， 在体内的实际RM组织托管早期传播的SIV感染。在S.A.1中，我们将定义全身性病毒 和未接种疫苗与（长期，以前保护和功能治愈）的免疫激活轨迹 68-1通过分析系列尸检，确定最佳接种后的RhCMV/SIV接种RM 研究进行性病毒血症前病毒传播的细胞免疫拦截的攻毒时间点，或 复制停滞的稳定建立。在S.A.2中，我们将使用此优化的RM模型来识别 RhCMV/SIV引起的免疫接种的幼稚RM中MHC-E限制性CD 8 + T细胞应答的特征， 通过比较病毒介导的SIV复制阻滞功效：这些应答的免疫拦截与MHC- 通过差异编程诱导幼稚RM中仅II型和仅MHC-Ia型SIV特异性CD 8 + T细胞应答 RhCMV载体和相对于由常规ChAdOx 1/MVA引起的MHC-Ia限制性CD 8 + T细胞应答 疫苗这些对比将提供重要的洞察免疫过程负责复制 抑制疗效并促进基于免疫机制的疗效相关性的发展， CMV为基础的HIV疫苗的临床转化。

PROJECT 2 - PROJECT SUMMARY Vaccination of Rhesus macaques (RMs) with SIV insert-expressing 68-1 Rhesus Cytomegalovirus vectors (RhCMV/SIV) elicits an immune response that in 59% of vaccinees can intercept and effectively arrest an early spreading primary SIV infection. This unique pattern of “replication arrest” efficacy has been linked to three 68- 1 RhCMV/SIV immune characteristics, including its ability to generate and maintain: 1) high magnitude, circulating and tissue-based, effector memory-biased CD8+ T cell responses, 2) major histocompatibility complex (MHC)-E-restricted SIV-specific CD8+ T cell responses and 3) in RMs with MHC-E-restricted CD8+ T cell responses, a protection-predictive innate immune transcriptional response to vaccination that includes a central IL-15 signaling component; however, the specific immune mechanism(s) underlying replication arrest protection are unknown. RhCMV/SIV vectors can now be programmed by genetic manipulation to elicit SIV-specific CD8+ T cell responses that are restricted by MHC-E-only, MHC-II-only and MHC-Ia-only, and while the latter 2 response types are similar in magnitude and phenotype to the MHC-E-restricted responses, they, as well as conventional prime-boost vaccine elicited MHC-Ia-restricted CD8+ T cell responses, are unable to mediate SIV replication arrest. This indicates that the protective (IL-15/innate-modulated) MHC-E-restricted SIV-specific CD8+ T cells must manifest a different response upon interception of primary SIV infection than the other T cell response types, possibly being more efficient in detecting and responding to SIV-infected cells in vivo and/or manifesting a different (more effective) functional program upon infected cell recognition. In this project, we will use sophisticated `omics technologies that enable detailed characterization of tissue immune responses (including specific analyses of T cell receptor-defined, SIV-specific CD8+ T cells) to define these differences in vivo in the actual RM tissues hosting an early spreading SIV infection. In S.A.1, we will define the systemic viral and immune activation trajectories of unvaccinated vs. (long-term, previously protected and functionally cured) 68-1 RhCMV/SIV vaccinated RMs by analysis of serial necropsies with the goal identifying the optimal post challenge timepoint(s) to study the cellular immune interception of viral spread prior to progressive viremia or stable establishment of replication arrest. In S.A.2, we will use this optimized RM model to identify the unique characteristics of RhCMV/SIV-elicited MHC-E-restricted CD8+ T cell responses in vaccinated naïve RMs that mediate SIV replication arrest efficacy by comparison of the viral:immune intercept of these responses vs. MHC- II-only and MHC-Ia-only SIV-specific CD8+ T cell responses elicited in naïve RMs by differentially programmed RhCMV vectors and vs. MHC-Ia-restricted CD8+ T cell responses elicited by the conventional ChAdOx1/MVA vaccine. These contrasts will provide important insight into the immune processes responsible for replication arrest efficacy and facilitate development of immune mechanism-based correlates of efficacy that will guide clinical translation of a CMV-based HIV vaccine.