Immune evasion by the Adenovirus E3-19K protein

描述（由申请人提供）：人体免疫系统的主要功能之一是通过控制入侵病原体的传播和毒力来引发保护免受感染的反应。 维持免疫力的核心是通过I类主要组织相容性复合体（MHC）分子将抗原肽呈递至CD 8+细胞毒性T淋巴细胞的细胞表面。 现在已经确定的是，病毒已经进化出选择性机制来破坏宿主的抗病毒细胞免疫防御并建立持续感染。 在大多数情况下，这些机制通过能够抑制I类MHC分子在细胞表面表达的病毒蛋白的作用而起作用。 本研究旨在探讨腺病毒中一种病毒蛋白的免疫调节功能。 Ad基因组包括许多编码免疫调节蛋白的基因，其中来自E3的19 kDa蛋白（E3- 19 K）是最好的特征。 E3- 19 K是一种I型膜蛋白，已显示其与Ad感染细胞的内质网（ER）中的I类MHC分子缔合，并阻止它们转运至细胞表面。 E3- 19 K的两个结构特征被认为是导致这些观察结果的原因：其内腔结构域与I类MHC分子的内腔结构域相关联，而其C-末端胞质尾部的功能是凭借ER-检索基序将I类MHC分子保留在ER中。 这个过程的几个分子和机制方面知之甚少。 本研究计划有两个具体目标：生产重组可溶性E3- 19 K并表征其生物化学和生物物理特性;以及在体外重建其与两种不同形式（肽填充和“空”）的重组可溶性I类MHC分子的相互作用。 这些研究将提供E3- 19 K与I类MHC分子结合区域的见解，以及直接证据表明E3- 19 K如何与I类组装途径中的一系列事件相关。 这些知识将增加我们对Ad发病机制和宿主细胞生物学的理解。 这对于我们预防、治疗和治愈与呼吸道、胃肠道、眼部和泌尿道疾病相关的广告诱导的免疫功能障碍的能力至关重要。 这些研究对于免疫和基因治疗也很重要，因为有可能使用广告作为载体来传递基因。

DESCRIPTION (provided by applicant): One of the primary functions of the human immune system is to elicit responses that protect against infections by controlling the spread and virulence of invading pathogens. Central to maintaining immunity is the cell-surface presentation of antigenic peptides to CD8+ cytotoxic T-lymphocytes by class I major histocompatibility complex (MHC) molecules. It is now well-established that viruses have evolved selective mechanisms to subvert the host antiviral cellular immune defenses and establish persistent infections. In most cases, these mechanisms operate by the action of viral proteins able to suppress the expression of class I MHC molecules at the cell-surface. This proposal is focused on investigating the immunomodulatory function of one such viral protein from Adenoviruses (Ads). The Ad genome includes a number of genes that code for immunomodulatory proteins, of which the 19 kDa protein from E3 (E3-19K) is the best characterized. E3-19K is a type I membrane protein that has been shown to associate with class I MHC molecules in the endoplasmic reticulum (ER) of Ad-infected cells, and prevent their transport to the cell-surface. Two structural features of E3-19K are thought to be responsible for these observations: its lumenal domain associates with the lumenal domain of class I MHC molecules, whereas its C-terminal cytosolic tail functions to retain class I MHC molecules in the ER by virtue of an ER-retrieval motif. Several molecular and mechanistic aspects of this process are poorly understood. This Research Plan has two specific goals; to produce recombinant, soluble E3-19K and characterize its biochemical and biophysical properties; and to reconstitute in vitro its interactions with two distinct forms, peptide-filled and "empty", of recombinant, soluble class I MHC molecules. These studies will provide insights in the region of E3-19K that binds to class I MHC molecules, as well as direct evidence to suggest how E3-19K may function in relation to the sequential series of events in the class I assembly pathway. This knowledge will increase our understanding of Ad pathogenesis and host cell biology. This is fundamental to our ability to prevent, treat, and cure, Ad-induced immune dysfunctions associated with respiratory, gastrointestinal, ocular, and urinary tract diseases. These studies are also important in relation to immunization and gene therapy given the potential to use Ads as vectors for the delivery of genes.