Evolution of CD8+ TCR affinity during chronic viral infection

描述（由申请人提供）：CD8+ T细胞是适应性免疫反应的关键组成部分，对控制病毒感染很重要。T细胞受体对抗原的亲和力触发CD8+ T细胞的激活并驱动抗病毒反应的程度。尽管亲和性在T细胞活化中起着关键作用，但我们对抗原识别的动态知之甚少，即亲和性的广度和随着免疫反应从初始触发阶段到记忆阶段的演变，亲和性的潜在变化。此外，我们缺乏关于急性感染期间T细胞亲和力差异的数据，急性感染引起有效的免疫反应，慢性感染时细胞免疫被证明无效。TCR亲和力对抗原识别的重要性和我们缺乏知识是研究这个问题的令人信服的理由。为了实现这些目标，我们建议使用微管粘附试验严格定义急性、慢性和表位丢失病毒感染期间CD8+ T细胞在二维（2D）上的亲和力宽度。最近的工作强调了二维动力学测量的重要性，以获得T细胞和APC相互作用的准确视图。虽然我们的建议主要集中在LCMV动物模型上，以证明概念的证明和定义亲和力的作用，但这些技术可以很容易地转移到患者样本中，以评估慢性感染（如HIV和HCV）期间的T细胞亲和力和CD8+ T细胞前体频率，其中肽抗原和HLA限制分子已经确定。提出的实验将增加我们对慢性免疫反应中T细胞生物学的认识，并应用于T细胞参与病理的任何情况。为了测试所述

DESCRIPTION (provided by applicant): CD8+ T cells are critical components of the adaptive immune response important for controlling viral infections. The affinity of T cell receptor for antigen triggers the activation of CD8+ T cells and drives the extent of the anti-viral response. Despite the key role of affinity in T cell activation, we still know quite little about the dynamic of antigen recognition in terms of the breadth of affinities and potential changes in affinity as the immune response evolves from initial triggering stage through memory. In addition, we lack data on differences in T cell affinities during acute infections, which elicit effective immune responses, and chronic infections where cellular immunity proves ineffective. The importance of TCR affinity for antigen recognition and our lack of knowledge are compelling reasons to investigate this issue. Toward these goals, we propose to use the micropipette adhesion assay to rigorously define the breadth of CD8+ T cell affinities in 2 dimensions (2D) during acute, chronic, and epitope loss viral infections. Recent work has highlighted the importance of 2D kinetic measurements to obtain an accurate view of T cell and APC interactions. While our proposal is focused toward the LCMV animal model to demonstrate proof of concept and define the role of affinity, the techniques could be readily transferred to patient samples to assess T cell affinity and CD8+ T cell precursor frequency during chronic infections such as HIV and HCV for which peptide antigens and HLA restriction molecules have been identified. The proposed experiments will increase our knowledge of T cell biology during chronic immune responses, with application to any situation in which T cells participate in the pathology. To test the stated hypotheses as to the breadth of the CD8+ anti-viral T cell response, we propose the following three specific aims: Aim 1- Determine the affinity profile of CD8+ T cells undergoing acute or chronic viral infections. Aim 2- Define the affinity profile and the parameters of diminished fitness of CD8+ T cells challenged by viral escape mutants. Aim 3- Characterize the affinity profile of CD8+ T cells after therapeutic interventions. PUBLIC HEALTH RELEVANCE: CD8+ T cells play a major role in the anti-viral immune response. The overall goal of this grant is to define the range of polyclonal T cell affinities for viral antigens during acute and chronic infections. The proposed studies apply a novel means for assessing affinity to the LCMV animal model, but our results should be equally translatable to human chronic infections such as HIV and HCV. Therefore, our findings are highly relevant to human health and will prove to be a valuable asset for assessing disease prognosis and for the development of effective treatments.