IMMUNOSUPPRESION BY MEASLES & CANINE DISTEMPER VIRUSES

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心赠款提供。子项目的主要支持 子项目的主要研究者可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 表示子项目使用的中心基础设施的估计数量， NCRR赠款不直接向子项目或子项目工作人员提供资金。 麻疹是一种发现了病毒诱导的免疫抑制现象的疾病：1908年，冯·皮尔凯观察到，在急性麻疹过程中，结核菌素皮肤试验反应短暂下降。麻疹病毒，包括麻疹（MV），犬瘟热（CDV）和牛瘟是免疫抑制。这种现象背后的机制是复杂的，但病毒受体相互作用可能发挥核心作用：野生型MV，CDV和牛瘟病毒株优先使用免疫细胞特异性蛋白SLAM（分别为人类，犬或牛）作为受体。此外，MV疫苗株Edmonston也优先通过补体激活的普遍存在的调节因子CD 46进入细胞，并且CD 46相互作用改变对MV的免疫应答。此外，由MV非结构蛋白V和C引起的进入后宿主控制逃避机制干扰STAT蛋白磷酸化和干扰素活化。我们将测试两个假设：第一，SLAM依赖的进入是至关重要的免疫抑制麻疹病毒。第二，V和C蛋白有利于病毒在免疫细胞和系统中传播。将使用两种动物模型：用于麻疹的猕猴和用于犬瘟热的雪貂。我们已经产生了选择性受体盲重组MV和CDV。我们正在构建野生型来源的MV和CDV，其中V或C或两种蛋白质的表达被沉默或增强。猕猴或雪貂将被鼻内感染，并将鉴定支持MV和CDV在PBMC以及淋巴和非淋巴器官中传播的细胞类型。毒力和免疫抑制将根据分级参数进行表征，包括疾病体征、白细胞数量、病毒血症的强度和持续时间、体外淋巴细胞增殖水平、中和抗体升数和细胞因子谱。我们预测这些参数的差异变化感染后的病毒缺陷的受体识别或后进入水平。结果将在这些预测结果的背景下进行解释。将根据感染性cDNA的功能测定、测序和反向转移，在疾病晚期复制的病毒中寻找毒力返强的候选突变。这些实验将确定通过特异性受体进入细胞和进入后宿主控制逃避机制在两个生物学相关的动物系统中对麻疹病毒诱导的免疫抑制的相对重要性。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Measles is the disease with which the phenomenon of virus-induced immunosuppression was discovered: in 1908 von Pirquet observed that the tuberculin skin test response was transiently depressed during the course of acute measles. Morbilliviruses including measles (MV), canine distemper (CDV) and rinderpest are immunosuppressive. The mechanisms underlying this phenomenon are complex, but viral receptor interactions may play a central role: wild-type MV, CDV and rinderpest virus strains preferentially use the immune cell-specific protein SLAM (human, canine or bovine, respectively) as a receptor. In addition, the MV vaccine strain Edmonston enters cells preferentially also through the ubiquitous regulator of complement activation, CD46, and CD46 interactions modify the immune response to MV. Moreover, post-entry host control evasion mechanisms elicited by the MV non-structural proteins V and C interfere with STAT protein phosphorylation and interferon activation. We will test two hypotheses: first, that SLAM-dependant entry is of central importance for immunosuppression by morbilliviruses. Second, that the V and C proteins favor virus dissemination in immune cells and systemically. Two animal models will be used: macaques for measles and ferrets for canine distemper. We have produced selectively receptor-blind recombinant MVs and CDVs. We are constructing wild type-derived MVs and CDVs in which the expression of V or C, or of both proteins, is silenced or enhanced. Macaques or ferrets will be infected intranasally and the cell types supporting MV and CDV dissemination in PBMC, and in lymphatic and non-lymphatic organs, will be identified. Virulence and immunosuppression will be characterized based on graded parameters including disease signs, leukocyte number, strength and duration of viremia, in vitro lymphocyte proliferation levels, neutralizing antibody liters, and cytokine profile. We predict differential changes in these parameters following infections with viruses defective at the receptor recognition or post-entry level. Results will be interpreted in the context of these predicted outcomes. Candidate mutations for reversion to virulence will be sought in viruses replicating at late disease stages based on functional assays, sequencing, and back-transfer in infectious cDNAs. These experiments will define the relative importance of cell entry through specific receptors and of post-entry host control evasion mechanisms for morbillivirus-induced immunosuppression in two biologically relevant animal systems.