Human Cytomegalovirus G Protein-Coupled Receptors

描述（由申请方提供）：人巨细胞病毒是β-疱疹病毒家族的原型成员。流行病学研究表明，人巨细胞病毒感染广泛存在。在健康的个体中，感染通常是无症状的，但该病毒可在免疫系统不成熟或受损的人中引起严重疾病。它是导致出生缺陷的主要传染病原因，也是移植受者中威胁生命的外源因子。该研究计划的长期目标是阐明人巨细胞病毒基因的功能，这些基因调节病毒与其宿主细胞的相互作用，从而控制病毒复制和发病机制。该提案旨在促进对HCMV编码的几种G蛋白偶联受体的理解。其中一种待研究的受体是US 28基因的产物。初步研究表明，缺乏US 28编码区的突变型人巨细胞病毒在感染G 0成纤维细胞后表现出加速的基因表达模式;早期和晚期mRNA在野生型病毒感染的成纤维细胞中检测到之前很久就积累了。在缺乏US 28受体的情况下，在野生型病毒感染中观察到的即刻早期、早期和晚期基因表达的时间依赖性级联被破坏。第一个具体的目标是描述HCMV编码的pUS 28对多种感染细胞类型内的转录级联的影响，并探索pUS 28作用的机制。第二个要研究的G蛋白偶联受体是UL 78基因的产物。该基因的鼠巨细胞病毒同源物被包装到病毒体中，并且在通过病毒体包膜与质膜融合将受体递送到细胞后，其促进病毒m123立即早期基因的激活。在第二个具体目标中，将在多种细胞类型中表征不表达UL 78产物的人巨细胞病毒突变体以探索该受体的功能。本项目将包括对人巨细胞病毒的实验室菌株（AD 169）和两种临床分离株（VR 1814、FIX和PH）的分析。病毒复制将在成纤维细胞中进行研究，成纤维细胞通常用于传播HCMV;主动脉内皮细胞和平滑肌细胞，与HCMV在动脉粥样硬化中的可能作用有关;视网膜色素上皮细胞，在病毒性视网膜炎中感染;和巨噬细胞，促进病毒传播。

DESCRIPTION (provided by applicant): Human cytomegalovirus is the prototypical member of the beta-herpes virus family. Epidemiological studies have shown that human cytomegalovirus infection is widespread. In healthy individuals infection is generally asymptomatic, but the virus can cause serious disease in people with immature or compromised immune systems. It is the leading infectious disease cause of birth defects and a life-threatening adventitious agent in transplant recipients. The long-term objective of this research program is to elucidate the function of human cytomegalovirus genes that regulate the interaction of the virus with its host cell and thereby control viral replication and pathogenesis. This proposal is designed to contribute to the understanding of several of the G protein-coupled receptors encoded by HCMV. One of the receptors to be studied is the product of the US28 gene. Preliminary studies have shown that a mutant human cytomegalovirus lacking the US28 coding region exhibits an accelerated pattern of gene expression after infection of G0 fibroblasts; early and late mRNAs accumulate long before they are detected in wild-type virus-infected fibroblasts. In the absence of the US28 receptor, the time-dependent cascade of immediate-early, early and late gene expression observed in wild-type virus infections is disrupted. The first specific aim seeks to characterize the effects of HCMV-coded pUS28 on the transcriptional cascade within multiple infected cell types and explore the mechanism of pUS28 action. The second G protein-coupled receptor to be studied is the product of the UL78 gene. The murine cytomegalovirus homologue of this gene is packaged into virions, and, after the receptor is delivered to cells by fusion of the virion envelope with the plasma membrane, it facilitates activation of the viral m123 immediate-early gene. In the second specific aim human cytomegalovirus mutants that do not express the UL78 product will be characterized in multiple cell types to explore the function of that receptor. This project will include analysis of a laboratory strain (AD169) and two clinical isolates (VR1814, FIX; and PH) of human cytomegalovirus. Viral replication will be studied in fibroblasts, the cell commonly used to propagate HCMV; aortic endothelial and smooth muscle cells, which are relevant to the possible role of HCMV in atherosclerosis; retinal pigmented epithelial cells, which are infected in viral retinitis; and macrophages, which facilitate virus spread.