Analysis of HCMV Infection of Monocytes and Macrophages

描述（由申请人提供）：人巨细胞病毒（HCMV）在免疫功能低下的患者（艾滋病和移植患者以及新生儿）中引起严重疾病。它还与免疫活性的慢性人类疾病有关。HCMV感染的一个关键特征是病毒的血行播散，这是疾病发病机制的核心。HCMV病毒血症是细胞相关的，但负责的细胞类型尚未最终确定。单核细胞可能是介导病毒传播的候选者。单核细胞是血液中感染的主要细胞类型，也是感染器官中发现的主要浸润细胞类型。问题是单核细胞不能被HCMV有效感染;病毒复制失败。巨噬细胞（区别于单核细胞）支持生产性病毒复制，感染的巨噬细胞在HCMV患者的多种组织中发现。然而，它们不是血液传播的细胞，不能负责血行传播。因此，目前的研究结果是矛盾的，参与HCMV传播的细胞类型仍然没有解决。我们提出了一个解决这个明显的难题，也就是说，单核细胞的HCMV感染驱动其特异性迁移出血液进入外周组织，在那里它们可以分化成巨噬细胞，然后可以复制从血液携带的原始病毒到组织中的感染的单核细胞。因此，我们认为HCMV具有驱动外渗和单核细胞向巨噬细胞分化的能力，这是病毒的关键功能。我们有初步数据支持这一建议。据我们所知，这种策略在其他病毒中的先例尚未报道，这与已知的HCMV发病机制一致。我们假设HCMV诱导单核细胞外渗到外周组织，并分化为生产性感染的巨噬细胞。具体目的如下：1）研究病毒结合是否启动单核细胞向巨噬细胞分化以及HCMV感染在单核细胞外渗中的作用; 2）检查病毒分化的巨噬细胞中的病毒基因表达和复制;以及3）确定与病毒诱导的单核细胞向巨噬细胞分化相关的分子信号传导机制。总的来说，本提案调查了HCMV传播和持续存在的机制。

DESCRIPTION (provided by applicant): Human cytomegalovirus (HCMV) causes severe disease in the immunocompromised (AIDS and transplant patients, and neonates). It is also associated with chronic human diseases in the immunocompetent. A critical feature of HCMV infections is the hematogenous dissemination of the virus that is central to disease pathogenesis. HCMV viremia is cell-associated, but the cell type responsible has not been conclusively identified. Monocytes are likely candidates to mediate viral dissemination. Monocytes are the primary cell type infected in the blood and are the predominant infiltrating cell type found in infected organs. The problem is that monocytes are not productively infected by HCMV; virus replication is abortive. Macrophages (differentiate from monocytes) support productive viral replication and infected macrophages are found in multiple tissues in HCMV patients. However, they are not blood-borne cells and cannot be responsible for hematogenous spread. Thus, current findings are contradictory and the cell type involved in HCMV spread remains unresolved. We propose a solution to this apparent conundrum and that is, that HCMV infection of monocytes drives their specific migration out of the blood into peripheral tissues, where they can differentiate into macrophages and can then replicate the original virus carried from the blood into the tissue by the infected monocytes. Therefore, we suggest that HCMV possesses the ability to drive extravasation and monocyte-to-macrophage differentiation and that this is a critical function of the virus. We have preliminary data to support this proposal. To our knowledge, a precedent for this strategy in other viruses has not been reported and it is consistent with what is known about HCMV pathogenesis. We hypothesize that HCMV induces extravasation of monocytes to peripheral tissues and their differentiation into productively infected macrophages. The specific aims are as follows: 1) to investigate if viral binding initiates monocyte-to-macrophage differentiation and the role of HCMV infection in monocyte extravasation; 2) to examine viral gene expression and replication in viral differentiated macrophages; and, 3) to determine the molecular signaling mechanisms associated with the viral-induced differentiation of monocytes into macrophages. Overall, this proposal investigates the mechanisms involved in HCMV spread and persistence.