Down-regulation of MHC class l molecules by HCMV US2

描述（由申请方提供）：人巨细胞病毒（HCMV）是一种β-疱疹病毒，可建立持续性和潜伏性感染。HCMV可导致免疫功能低下个体如移植受体和HIV感染者的发病率和死亡率。事实上，HIV阳性患者有患HCMV相关性失明的风险。HCMV也是新生儿出生缺陷的主要传染性原因，导致听力障碍和轻度精神发育迟滞。免疫系统对病毒的选择性压力导致它们能够产生逃避策略以避免免疫检测。HCMV表达调节免疫系统的先天和适应性分支的蛋白质。细胞免疫似乎是HCMV的主要靶点，其重点在于干扰CD 8+细胞毒性T细胞（CTL）活化。来自基因组US 2、US 3、US 6和US 11的独特短区域的HCMV编码基因产物通过阻止主要组织相容性复合体（MHC）I类分子的表面表达来干扰HCMV感染细胞的CTL识别。这种策略将限制HCMV感染早期阶段针对HCMV表位的CTL的频率，并允许HCMV逃避免疫检测。US 2和US 11靶向I类分子用于蛋白酶体降解。最近的证据表明，US 2也可能靶向MHC II类DR α和DM α分子的蛋白酶体降解。这表明US 2是调节免疫系统的HCMV病毒蛋白库中的重要基因。为此，我们将确定US 2负责靶向MHC I类分子进行破坏的特定区域，并确定促进降解过程的细胞蛋白。我们将模拟HCMV感染的早期阶段，并确定US 2在其他病毒基因产物如US 3和US 11中的功能。充分了解HCMV US 2如何操纵宿主的细胞机制以防止MHC I类和II类抗原呈递，可能允许设计阻断US 2功能的药剂。

DESCRIPTION (provided by the applicant): Human cytomegalovirus (HCMV) is a beta-herpes virus that can establish persistence and latent infections. HCMV can cause morbidity and mortality in immuno-compromised individuals such as transplant-recipients and HIV-infected persons. In fact, HIV-positive patients are at risk of HCMV-related blindness. HCMV is also a major infectious cause of birth defects in newborns causing hearing disturbances and mild forms of mental retardation. Selective pressure by the immune system on viruses has resulted in their ability to generate evasive tactics to avoid immune detection. HCMV expresses proteins that modulate both the innate and adaptive branches of the immune system. Cellular immunity appears to be the main target of HCMV with an emphasis on interfering with CD8+ cytotoxic T cell (CTL) activation. HCMV encoded gene products from the unique short region of the genome US2, US3, US6 and US11 interfere with CTL recognition of HCMV-infected cells by preventing the surface expression of major histocompatibility complex (MHC) class I molecules. This strategy would limit the frequency of CTLs directed against HCMV epitopes during the early phase of HCMV infection and allow HCMV to escape immune detection. US2 and US11 target class I molecules for proteasomal degradation. Recent evidence suggests that US2 may also target the MHC class II DRalpha and DMalpha molecules for proteasomal degradation. This suggests that US2 is an important gene in the HCMV repertoire of viral proteins that modulates the immune system. To that end, we will define the specific regions of US2 responsible for targeting MHC class I molecules for destruction as well as identify the cellular proteins that facilitates the degradation process. We will mimic the early phase of HCMV infection and determine the function of US2 in the context of other viral gene products such as US3 and US11. A full understanding of how HCMV US2 manipulates the cellular machinery of the host to prevent MHC class I and class II antigen presentation may permit the design of pharmaceutical agents that block US2 function.