Immune evasion by SARS-CoV-2: the role of HLA class I

SARS-CoV-2 的免疫逃避：HLA I 类的作用

• 批准号: 10575292
• 负责人: MARLENE BOUVIER
• 金额: $ 23.99万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-11-17 至 2024-10-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10575292
• 关键词: 2019-nCoV; Address; Affect; Alleles; Antigen Presentation; Binding; Biological Assay; Biology; CD8-Positive T-Lymphocytes; COVID-19; COVID-19 pathogenesis; COVID-19 treatment; Cell surface; Cells; Cellular Immunity; Characteristics; Code; Complex; Coronavirus; Crystallization; Data; Development; Diagnosis; Disease; Down-Regulation; Endowment; Epitopes; Evaluation; Flow Cytometry; Future; Genomic Segment; Goals; Growth; HLA-A gene; HLA-B Antigens; HLA-C Antigens; Histocompatibility; Histocompatibility Antigens Class I; Immune; Immune Evasion; Impairment; In Vitro; Innate Immune Response; Interferon Type I; Investigation; Knowledge; Mediating; Molecular; Morbidity - disease rate; Mutation; NK Cell Activation; Natural Immunity; Natural Killer Cells; Nuclear; Open Reading Frames; Pathogenesis; Pathologic; Pathway interactions; Patients; Phenotype; Proteins; Research; Role; SARS coronavirus; SARS-CoV-2 genome; SARS-CoV-2 infection; SARS-CoV-2 pathogenesis; Scheme; Specificity; Structure; Surface; System; T cell response; Variant; Viral; Virulence; Virus; Virus Replication; adaptive immune response; adaptive immunity; antiviral immunity; cellular transduction; clinically relevant; current pandemic; exhaustion; experience; gel electrophoresis; human pathogen; immune function; in vivo; innovation; interest; mortality; mutant; novel; novel therapeutics; pandemic coronavirus; pandemic disease; pathogen; pressure; prevent; protein protein interaction; response; severe COVID-19; small molecule inhibitor; therapeutic development

ABSTRACT Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is responsible for the current pandemic of coronavirus-induced disease 2019 (COVID-19). Since December 2019, coordinated research efforts have provided a wealth of critical data that have enhanced our ability to diagnose and treat COVID-19. To date, however, much of the molecular and cellular mechanisms underlying the pathogenesis of COVID-19 remain elusive. The genome of SARS-CoV-2 contains nine independent open reading frames (ORFs) coding for proteins that are not essential for viral replication but seem to exert important functions in modulating host antiviral immunity. Of these accessory proteins, the ORF8 protein stands out for its unique characteristics. ORF8 is a highly variable protein among SARS-related CoVs. ORF8 also appears to be involved in a network of host-pathogen interactions inside infected cells: ORF8 impairs immune pathways such as antigen presentation, interferon type I, and nuclear factor-kB, as well as possibly activate growth pathways. A central question is how ORF8 mediates interactions with multiple host protein targets. Towards this goal, we are investigating ORF8 interaction with major histocompatibility class I (MHC I) molecules. It was shown recently that SARS-CoV-2 ORF8 suppresses CD8+ T cell responses by downregulating MHC I molecules, both in vitro and in vivo. We hypothesize that ORF8 suppresses surface expression of HLA-A and HLA-B molecules to protect infected cells from recognition by CD8+ T cells, but spares HLA-C and HLA-E to avoid activation of natural killer (NK) cells. The possibility that ORF8 displays a locus specificity toward MHC I would provide a mechanism for SARS-CoV-2 to walk a fine line between adaptive and innate immunity. Specifically, we will undertake an analysis of interactions between ORF8 and MHC I by using a panel of HLA- A, -B, -C, and -E molecules, and also determine if ORF8 selectively downregulates MHC I in relevant cell systems (Aim 1). We will extend these studies to ORF8 variants that have been positively selected during the course of the pandemic and evaluate if and how these mutations affect MHC I binding and downregulation (Aim 2). The successful completion of these Aims is expected to uncover unknown features of ORF8 and elucidate its role in suppressing antigen presentation, as well as inform us on the selective pressure that MHC I exerts on SARS-CoV-2. The immediate and long-term impact of our proposed research is high. This is the first study that: (1) characterizes molecular interaction of ORF8 with a host protein; and (2) evaluates clinically relevant ORF8 variants. By studying the immune interactions underlying ORF8-mediated downregulation of MHC I, we will increase our understanding of how SARS-CoV-2 derails cellular immunity. Importantly, our study will stimulate similar investigations of other ORF8-interactors, providing novel opportunities for the development of therapeutics directed against ORF8 or its host targets.

抽象的 严重急性呼吸综合征冠状病毒-2 (SARS-CoV-2) 是造成当前大流行的罪魁祸首 2019 年冠状病毒引起的疾病 (COVID-19)。自 2019 年 12 月以来，协调研究工作已 提供了大量的关键数据，增强了我们诊断和治疗 COVID-19 的能力。迄今为止， 然而，COVID-19 发病机制的许多分子和细胞机制仍然存在 难以捉摸。 SARS-CoV-2 的基因组包含九个独立的开放阅读框 (ORF)，编码 对病毒复制不是必需的但似乎在调节宿主中发挥重要功能的蛋白质 抗病毒免疫力。在这些辅助蛋白中，ORF8 蛋白因其独特的特性而脱颖而出。 ORF8 是 SARS 相关冠状病毒中高度变异的蛋白质。 ORF8 似乎也参与了网络 受感染细胞内宿主与病原体相互作用的影响：ORF8 损害抗原等免疫途径 呈递、I 型干扰素和核因子-kB，并可能激活生长途径。一个中央 问题是 ORF8 如何介导与多个宿主蛋白靶标的相互作用。为了这个目标，我们 研究 ORF8 与主要组织相容性 I 类 (MHC I) 分子的相互作用。 最近发现 SARS-CoV-2 ORF8 通过下调 MHC 抑制 CD8+ T 细胞反应 I 分子，体外和体内。我们假设 ORF8 抑制 HLA-A 的表面表达， HLA-B 分子可保护受感染的细胞不被 CD8+ T 细胞识别，但不保留 HLA-C 和 HLA-E 避免激活自然杀伤 (NK) 细胞。 ORF8 对 MHC I 显示位点特异性的可能性 将为 SARS-CoV-2 提供一种在适应性免疫和先天免疫之间游走的机制。 具体来说，我们将使用一组 HLA- 来分析 ORF8 和 MHC I 之间的相互作用。 A、-B、-C 和 -E 分子，并确定 ORF8 是否选择性下调相关细胞中的 MHC I 系统（目标 1）。我们将把这些研究扩展到 ORF8 变体，这些变体是在 大流行的过程并评估这些突变是否以及如何影响 MHC I 结合和下调 （目标 2）。这些目标的成功完成预计将揭示 ORF8 的未知特征和 阐明其在抑制抗原呈递中的作用，并告知我们 MHC I 的选择压力 对 SARS-CoV-2 发挥作用。我们提出的研究的直接和长期影响很大。这是第一个 研究：(1) 表征 ORF8 与宿主蛋白的分子相互作用； (2) 临床评估 相关 ORF8 变体。通过研究 ORF8 介导的下调的免疫相互作用 MHC I，我们将加深对 SARS-CoV-2 如何破坏细胞免疫的了解。重要的是，我们的 研究将刺激其他 ORF8 相互作用子的类似研究，为 针对 ORF8 或其宿主靶标的疗法的开发。