Role of Glycoprotein B in HCMV infection

描述(申请人提供)：人类巨细胞病毒(HCMV)是一种医学上重要的病原体，与免疫缺陷人群的严重临床疾病有关。近年来，医学研究人员认识到，人巨细胞病毒感染也与一些增殖性疾病有关，如心血管疾病、慢性肠炎性疾病和胃肠癌。这些表现的核心是对细胞机械的病毒编程劫持。巨细胞病毒直接调节信号转导途径，促进细胞过程的改变，全球改变基因表达，并诱导炎症细胞因子等疾病介质。巨细胞病毒被膜蛋白与细胞受体的相互作用是许多这些变化的始发者。人巨细胞病毒包膜糖蛋白B(GB)在感染过程中发挥着重要作用，包括受体结合、膜融合和信号转导通路激活等。相应地，英国队正处于严密的东道主监视之下。Gb由病原体传感器识别，称为Toll样受体，是宿主先天免疫的触发者，这是我们实验室在前一个资助期发现的。适应性免疫系统的两个分支也识别GB。它能产生强大的中和抗体，并具有细胞毒性T细胞反应识别的多个表位。这些研究的目标是确定GB与细胞分子相互作用的分子基础。我们还试图描述这些相互作用的后果和细胞反应，希望这些知识将对HCMV的发病机制产生有价值的见解。在之前的资助阶段，我们发现HCMV参与了细胞整合素作为进入介质和信号分子的作用。我们还在GB的氨基末端检测到一个新的去整合素样结构域，它与细胞整合素结合蛋白具有同源性。值得注意的是，这个结构域在所有的贝塔和许多伽马疱疹病毒中都是高度保守的，这表明整合素可能是这组具有医学意义的病原体的辅助受体。本文提出的研究将检验一种假设，即gB去整合素样结构域直接介导细胞整合素的参与，这种相互作用的结果是启动下游事件，如膜融合、衣壳-被膜转位和/或基因表达。我们还发现，预测阿尔法螺旋线圈的七重复制区存在于GB中，并且在感染的穿透阶段很重要。去整合素样区和七肽重复区都将接受遗传分析。在与贝塔多肽技术先驱萨姆·盖尔曼博士的合作研究中，我们将合成和表征GB盘绕结构域的贝塔多肽模拟物。这些数据将被用来开发合理的抗融合基因模拟物，这些模拟物最终可能在治疗HCMV病方面有用。

DESCRIPTION (provided by applicant): Human cytomegalovirus (HCMV) is a medically significant pathogen associated with severe clinical disease in immune deficient people. In recent years, medical researchers have gained appreciation that HCMV infection is also associated with a number of proliferative diseases such as cardiovascular disease, chronic bowel inflammatory disease and gastro-intestinal cancer. At the core of these manifestations is a virally programmed highjacking of cellular machinery. HCMV directly modulates signal transduction pathways, promotes changes in cellular processes, globally alters gene expression and induces disease mediators such as inflammatory cytokines. Interactions of HCMV envelope proteins with cellular receptors are the initiators of many of these changes. HCMV envelope glycoprotein B (gB) plays several fundamental roles in infection including receptor binding, membrane fusion, and activation of signal transduction pathways. Correspondingly, gB is under intense host surveillance. gB is recognized by pathogen sensors known as Toll-like receptors and serves as a trigger of host innate immunity, a discovery made by our laboratory in the previous funding period. Both branches of the adaptive immune system also recognize gB. It elicits potent neutralizing antibodies and has multiple epitopes recognized by cytotoxic T cell responses. The goal of these studies is to define the molecular underpinnings of the interactions of gB with cellular molecules. We also seek to characterize the consequences and cellular responses to these interactions in hopes that this knowledge will yield valuable insights into HCMV pathogenesis. In the previous funding period, we discovered that HCMV engages cellular integrins as entry mediators and signaling molecules. We also detected a novel disintegrin-like domain in the amino terminus of gB that had homology to cellular integrin binding proteins. Strikingly, this domain is very highly conserved in all beta and many gamma herpesviruses suggesting that integrins may serve as co-receptors for this medically significant group of pathogens. Studies proposed herein will test the hypothesis that the gB disintegrin-like domain directly mediates engagement of cellular integrins and that the consequence of this interaction is to prime downstream events such as membrane fusion, capsid-tegument translocation and/or gene expression. We also discovered that heptad repeat regions predictive of alpha helical coil-coils are present in gB and are important in the penetration stage of infection. Both the disintegrin-like domain and heptad repeat region will be subject to genetic analysis. In collaborative studies with Dr. Sam Gellman, a pioneer in beta-peptide technology, we will synthesize and characterize beta-peptide mimics of the gB coiled-coil domain. These data will be used to develop rational design of anti-fusogenic mimics that may ultimately be useful in treatment of HCMV disease.