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激活分子（SLAM）和补体激活膜辅助因子蛋白（MCP; CD46）。野生型MV使用SLAM作为细胞进入端口；Edmonston活疫苗株有效地利用CD46。即使强烈的CD46相互作用与MV衰减相关，其他病原体（三种病毒和两种细菌）也会靶向CD46，这表明CD46促进了病原体的传播。本文提出的研究将进一步表征受体参与的机制，并评估这些相互作用对感染进展的影响。我们将验证两个假设：第一，结合具有给定亲和力的SLAM维持特定类型免疫细胞感染的快速进展。其次，低亲和力的CD46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。我们的实验计划有三个目标。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CD46蛋白表面的模型。同时，我们将生产可溶性突变蛋白外结构域，通过表面等离子体共振测量它们的结合动力学，并使用结果指导进一步的模型构建和测试周期。为了了解结合动力学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标准H蛋白方面的能力。目的2将评估SLAM和CD46相互作用在人淋巴样细胞MV感染中的作用。我们将用具有选择性受体特异性的病毒感染人类扁桃体中保留器官样结构的组织块和外周血单个核细胞，并评估它们是否具有预测的细胞特异性复制模式。目的3将评估CD46相互作用对生物体中MV感染进展和上皮浸润的重要性。我们将比较野生型和疫苗型MV在小鼠中除了SLAM外表达CD46或不表达CD46的感染，并评估CD46相互作用对病毒传播是否有积极或消极的影响。麻疹每年仍造成约60万儿童死亡。受体结合，即病毒与其宿主之间的初始相互作用，是疾病结局的关键决定因素。更详细地了解麻疹病毒如何与受体结合，将有助于设计用于免疫抑制患者的更多减毒疫苗株。它还将进一步促进目标溶瘤病毒的发展。

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.