Analysis of MHC Class Ib-Restricted Polyoma Virus-Specific CD8 T Cells

摘要 细胞内病原体的免疫监视主要由传统的TCR、CD 8 T介导。 淋巴细胞识别由高度多态性的“经典”或 MHC Ia类分子。然而，越来越多的人认识到，这些寡型“非经典”或MHC Ib类分子也可呈递病原体衍生的抗原。然而，迄今为止的证据表明， MHC-Ib-限制性CD 8 T细胞介导的免疫力是宿主防御细胞内细菌感染的一种机制， 感染.使用小鼠多瘤病毒（PyV）模型，我们最近发现缺乏MHC类抗原的小鼠， Ia类分子但保留MHC Ib类分子（即，Kb-/-Db-/-小鼠）与其野生型一样具有抗性 对应于这种病毒的致癌潜力，有效地控制急性和持续阶段， 感染，并以CD 8 T细胞依赖的方式进行。我们鉴定了病毒肽及其MHC类 Ib限制性分子，构建了MHC-I四聚体试剂，并跟踪了MHC-I的进化、功能完整性， 并在整个PyV感染过程中维持这些新的非常规CD 8 T细胞。 重要的是，我们确定了这些抗病毒CD 8 T细胞提供针对PyV感染的保护， 构成抗病毒CD 8 T细胞库的先前未被认识的组分。我们的新数据 提供了第一个证据，证明一个明确的MHC Ib类限制性抗病毒CD 8 T细胞应答， 来主持防守本应用程序的总体目标是使用小鼠PyV感染系统， 全面定义引发这些非常规CD 8 T细胞的要求，并应用见解 从这些研究中评估候选干预措施，以促进抗病毒CD 8 T细胞的招募， MHC Ia类同种异体屏障。提出了三个具体目标：（1）确定以下要求： 选择和维持PyV特异性、MHC Ib类限制性CD 8 T细胞;（2）研究 解释大多数这些T细胞功能受损的发现的机制;和（3） 确定CD 4 T细胞的贡献，并选择共刺激途径， 功能性抗PyV MHC Ib类限制性CD 8 T细胞，以促进对小鼠中PyV感染的控制。 MHC-Ia同种异体株。公共卫生相关性：这些研究应该激励人们努力揭示 在其他病毒感染中的MHC Ib类限制性CD 8 T细胞应答，并且，考虑到MHC Ib类限制性CD 8 T细胞的有限多态性， MHC Ib类分子为开发具有广泛免疫原性的基于肽的病毒疫苗提供了平台。 覆盖整个MHC单倍型。

ABSTRACT Immunosurveillance for intracellular pathogens is primarily mediated by conventional TCR¿¿ CD8 T lymphocytes that recognize pathogen-derived oligopeptides presented by the highly polymorphic "classical" or MHC class Ia molecules. Yet, there is growing appreciation that these oligomorphic "nonclassical" or MHC class Ib molecules may also present pathogen-derived antigens. Evidence to date, however, has suggested that MHC-Ib-restricted CD8 T cell-mediated immunity is relegated to host defense against intracellular bacterial infections. Using the mouse polyoma virus (PyV) model, we recently discovered that mice lacking MHC class Ia molecules but retaining MHC class Ib molecules (i.e., Kb-/-Db-/- mice) are as resistant as their wild type counterparts to the oncogeneic potential of this virus, efficiently control acute and persistent phases of infection, and do so in a CD8¿¿ T cell-dependent manner. We identified the viral peptide and its MHC class Ib-restricting molecule, constructed MHC-I tetrameric reagents, and tracked the evolution, functional integrity, and maintenance of these novel unconventional CD8 T cells throughout the course of PyV infection. Importantly, we determined that these antiviral CD8 T cells confer protection against PyV infection, and constitute a previously unappreciated component of the antiviral CD8 T cell repertoire. Our new data thus provides the first evidence for a defined MHC class Ib-restricted antiviral CD8 T cell response that contributes to host defense. The overall goal of this application is to use the mouse PyV infection system to comprehensively define the requirements for eliciting these unconventional CD8 T cells, and to apply insights from these studies to evaluate candidate interventions to promote recruitment of antiviral CD8 T cells across MHC class Ia allogeneic barriers. Three Specific Aims are proposed: (1) to define the requirements for selection and maintenance of PyV-specific, MHC class Ib-restricted CD8 T cells; (2) to investigate mechanism(s) to explain the finding that the majority of these T cells are functionally compromised; and (3) to define the contributions of CD4 T cells and select costimulatory pathways in generating and maintaining functional anti-PyV MHC class Ib-restricted CD8 T cells in order to promote control of PyV infection in mice of MHC-Ia allogeneic strains. PUBLIC HEALTH RELEVANCE: These studies should motivate efforts to uncover MHC class Ib-restricted CD8 T cell responses in other viral infections, and, given the limited polymorphism of MHC class Ib molecules, provide a platform for developing peptide-based viral vaccines having broad coverage across MHC haplotypes.