IMMUNOSUPPRESION BY MEASLES & CANINE DISTEMPER VIRUSES

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 麻疹是一种病毒诱导的免疫抑制现象被发现的疾病：1908年，冯·皮尔奎特观察到，在急性麻疹过程中，结核菌素皮试反应一过性地受到抑制。麻疹(MV)、犬瘟热(CDV)和牛瘟等麻疹病毒具有免疫抑制作用。这种现象背后的机制很复杂，但病毒受体的相互作用可能起到核心作用：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、犬或牛)作为受体。此外，MV疫苗毒株Edmonston也通过补体激活的普遍调节因子优先进入细胞，CD46和CD46相互作用调节对MV的免疫应答。此外，MV非结构蛋白V和C的进入后宿主控制逃避机制干扰STAT蛋白的磷酸化和干扰素的激活。我们将检验两个假设：第一，SLAM依赖的进入对麻疹病毒的免疫抑制具有核心重要性。第二，V蛋白和C蛋白有利于病毒在免疫细胞和系统内的传播。将使用两种动物模型：猕猴用于麻疹，雪貂用于犬瘟。我们已经选择性地生产了受体不敏感的重组MVS和CDV。我们正在构建野生型衍生的MVS和CDV，在这些MVS和CDV中，V或C或这两种蛋白的表达被沉默或增强。猕猴或雪貂将被鼻内感染，并将确定支持MV和CDV在PBMC以及淋巴和非淋巴器官传播的细胞类型。毒力和免疫抑制将基于分级参数来表征，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、中和抗体滴度和细胞因子谱。我们预测在感染受体识别缺陷或进入后水平的病毒后，这些参数会发生不同的变化。结果将在这些预测结果的背景下进行解释。基于功能分析、测序和感染性cDNA的反向转移，将在疾病晚期复制的病毒中寻找恢复毒力的候选突变。这些实验将确定通过特定受体进入细胞和进入后宿主控制逃避机制在两个生物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.