Using a novel neonatal mouse model to determine mechanisms of norovirus-induced disease

项目总结/摘要 诺如病毒是世界各地严重儿童腹泻的主要原因，也是急性腹泻的主要原因。 所有年龄组的肠胃炎。目前还没有批准的疫苗或针对诺如病毒的靶向治疗药物 感染和很少知道的致病机制，胃肠炎的症状。获得 为了进一步了解这种重要的病毒，鼠诺如病毒多年来一直被用作模型系统 并在理解诺如病毒生物学方面取得了许多重大进展。然而，缺乏 感染鼠诺如病毒的免疫活性成年小鼠的症状限制了该模型的适用性， 疾病的病毒机制的描述。我们最近发现基因野生型新生小鼠 当感染鼠诺如病毒时，会出现急性、自行消退的腹泻，这是一种与人类相似的疾病过程。 诺如病毒感染诺如病毒病的这种新型小动物模型代表了在 诺如病毒领域，因为它将使病毒疾病机制的完整表征，并最终服务于 作为测试体内抗病毒化合物功效的平台。在开发这个新模型时，我们观察到 遗传相似的鼠诺如病毒株之间疾病严重程度的差异， 诺如病毒引起的疾病的决定因素。本提案的目的是阐明细胞的 嗜性和致病机制的基础诺如病毒腹泻使用我们的新的症状小 动物模型在具体目标1中，我将检验淋巴细胞感染对诺如病毒至关重要的假设- 引起腹泻。这一假设得到了我们体外研究结果的有力支持， 弱毒株在巨噬细胞中复制噬菌体，只有强毒株在淋巴细胞中复制。 此外，在体外消除淋巴细胞感染的突变在成年干扰素缺陷小鼠中减弱。在 具体目标2，我将测试病毒诱导的促炎细胞因子引起的紧张性细胞分裂的假设。 连接维持肠上皮屏障，从而导致肠通透性增加 和腹泻。这一假设是基于我们的观察，即强毒鼠诺如病毒株诱导 尽管病毒水平相当，但促炎细胞因子的表达显著高于减毒株。 复制;以及促炎细胞因子破坏紧密连接的良好能力。总体看 本提案中描述的研究将测试我们的模型，即诺如病毒感染肠道免疫细胞诱导 一种免疫病理学的宿主反应，通过影响肠上皮屏障导致腹泻。

Project Summary/Abstract Norovirus is the leading cause of severe childhood diarrhea around the world and a major cause of acute gastroenteritis in all age groups. There are no currently approved vaccines or targeted therapeutics for norovirus infection and very little is known about the pathogenic mechanisms underlying gastroenteritis symptoms. To gain further understanding of this important virus, murine norovirus has been used as a model system for many years and has led to many significant advances in understanding norovirus biology. However, the absence of symptoms in immunocompetent adult mice infected with murine norovirus limits the applicability of this model to delineation of viral mechanisms of disease. We recently discovered that genetically wild-type neonatal mice develop acute, self-resolving diarrhea when infected with murine norovirus, a disease course that mirrors human norovirus infection. This novel small animal model of norovirus disease represents a major advance in the norovirus field since it will enable a complete characterization of viral disease mechanisms and ultimately serve as a platform to test the efficacy of antiviral compounds in vivo. While developing this new model, we observed differences in disease severity between genetically similar murine norovirus strains enabling identification of viral determinants of norovirus-induced disease. The objectives of this proposal are to elucidate the cellular tropism and pathogenic mechanisms underlying norovirus diarrhea using our novel symptomatic small animal model. In Specific Aim 1, I will test the hypothesis that infection of lymphocytes is critical to norovirus- induced diarrhea. This hypothesis is strongly supported by our in vitro findings revealing that, although virulent and attenuated strains replicate comparably in macrophages, only the virulent strain replicates in lymphocytes. Moreover, mutations abolishing lymphocyte infection in vitro are attenuating in adult interferon-deficient mice. In Specific Aim 2, I will test the hypothesis that virus-induced proinflammatory cytokines cause disruptions in tight junctions maintaining the intestinal epithelial barrier, consequently leading to increased intestinal permeability and diarrhea. This hypothesis is based on our observation that a virulent murine norovirus strain induces significantly more proinflammatory cytokine expression than attenuated strains despite comparable levels of viral replication; and on the well-established ability of proinflammatory cytokines to disrupt tight junctions. Overall, the studies described in this proposal will test our model that norovirus infection of intestinal immune cells induces a host response that is immunopathologic and leads to diarrhea via effects on the intestinal epithelial barrier.