Measles Virus Entry: Engagement of the Receptors and Infection Progression

描述（由申请人提供）：麻疹仍然是儿童死亡的主要原因之一。麻疹病毒（MV）与两种细胞受体相互作用：免疫细胞特异性蛋白信号淋巴细胞活化分子（SLAM）和补体活化膜辅因子蛋白（MCP; CD 46）的普遍存在的调节剂。野生型MV使用SLAM作为细胞进入的端口;活疫苗株Edmonston另外有效地使用CD 46。即使强的CD 46相互作用与MV减毒相关，其他病原体（三种病毒和两种细菌）靶向CD 46，表明CD 46促进病原体的传播。本文提出的研究将进一步表征受体的参与机制，并评估这些相互作用对感染进展的影响。我们将测试两个假设：第一，以给定亲和力结合SLAM在选定类型的免疫细胞中维持感染的快速进展。第二，低亲和力的CD 46相互作用有利于病毒的传播，但高亲和力的相互作用会干扰病毒的传播。在目标1中，我们将描述病毒附着蛋白如何与其受体结合：我们将建立接触后被掩埋的MV H、SLAM和CD 46蛋白表面的模型。同时，我们将产生可溶性突变蛋白胞外域，通过表面等离子体共振测量其结合动力学，并使用结果指导进一步的模型构建和测试循环。为了了解结合动力学的变化对膜融合和细胞进入的影响，我们将评估突变的膜结合H蛋白在支持膜融合和取代病毒中的标准H蛋白的能力。目的2将评估SLAM和CD 46相互作用在MV感染人淋巴细胞中的作用。我们将用具有选择性受体特异性的病毒感染保留器官样结构的人扁桃体组织块和外周血单核细胞，并评估它们是否具有预测的细胞特异性复制模式。目的3：探讨CD 46相互作用对MV感染和上皮细胞侵袭的重要性。我们将比较野生型和疫苗MV在除了SLAM之外还表达或不表达CD 46的小鼠中的感染，并评估CD 46相互作用对病毒传播是否具有积极或消极影响。这项研究与公共卫生的相关性麻疹每年仍导致约60万儿童死亡。受体结合是病毒与其宿主之间的初始相互作用，是疾病结果的关键决定因素。更详细地了解麻疹病毒如何与其受体结合，将有助于设计用于免疫抑制患者的更减毒疫苗株。它还将促进靶向溶瘤病毒的进一步发展。

DESCRIPTION (provided by applicant): Measles remains one of the leading causes of children death. Measles virus (MV) interacts with two cellular receptors: the immune cell-specific protein signaling lymphocyte activation molecule (SLAM) and the ubiquitous regulator of complement activation membrane cofactor protein (MCP; CD46). Wild type MV use SLAM as a port of cell entry; the live vaccine strain Edmonston efficiently uses CD46 in addition. Even if strong CD46 interactions correlate with MV attenuation, other pathogens (three viruses and two bacteria) target CD46, suggesting that CD46 facilitates pathogen's spread. The research proposed here will further characterize the mechanisms of engagement of the receptors and assess the consequences of these interactions for infection progression. We will test two hypotheses: first, that binding SLAM with a given affinity sustains rapid progression of infection in selected types of immune cells. Second, that low affinity CD46 interactions favor virus spread, but high affinity interactions interfere with it. Our experimental plan foresees three aims. In aim 1 we will characterize how the viral attachment protein engages its receptors: we will build models of the surfaces of the MV H, SLAM and CD46 proteins that are buried after contact. In parallel we will produce soluble mutant protein ectodomains, measure their binding kinetics by surface plasmon resonance, and use the results to instruct further cycles of model building and testing. To understand the effects of changes in binding kinetics on membrane fusion and cell entry we will assess the competence of mutant membrane-bound H proteins in supporting membrane fusion, and in substituting the standard H protein in viruses. Aim 2 will assess the role of SLAM and CD46 interactions for MV infection of human lymphoid cells. We will infect blocks of tissues from human tonsils that retain an organ-like architecture, and peripheral blood mononuclear cells, with viruses with selective receptor specificity and assess whether they have the predicted cell-specific pattern of replication. Aim 3 will appraise how important CD46 interactions are for the progression of MV infection and epithelia invasion in an organism. We will compare infections of wild type and vaccine MV in mice that do or don't express CD46 in addition to SLAM and assess whether CD46 interactions have a positive or negative effect on virus spread. RELEVANCE OF THIS RESEARCH TO PUBLIC HEALTH Measles still causes the death of about 600,000 children yearly. Receptor engagement, the initial interaction between a virus and its host, is a critical determinant of disease outcome. More detailed understanding of how measles virus engages its receptors will facilitate the design of more attenuated vaccine strains for use in immunosuppressed patients. It will also boost further development of oncolytic viruses, targeted.