Development of Murine Model for SARS-CoV Pathogenesis

严重急性呼吸系统综合症(SARS)是一种发病率和死亡率都很高的人类疾病，于2002年底首次被发现。几个月内，一种人类冠状病毒SARS-CoV被确定为这种疾病的病原体。对这种感染的发病机制知之甚少，但几个特征表明，这种疾病在一定程度上是免疫病理的。相比之下，关于冠状病毒诱导的机制知道得更多。 动物中的疾病。具体地说，关于免疫介导的脱髓鞘已经了解了很多。 小鼠肝炎病毒引起的疾病，一种小鼠冠状病毒，很大程度上是因为有有用的动物模型可供研究。目前，只有非人灵长类动物才能通过实验感染SARS-CoV。虽然这些动物将对一些研究有用，但如果能开发出一种小型啮齿动物模型来回答有关SARS-CoV发病机制的问题并评估治疗措施，那将是非常有价值的。 因此，该项目的中心目标将是开发和表征SARSCoV的动物模型。这一目标将通过以下具体目标来实现。具体目的1.建立利用靶向重组技术研究SARS-CoV基因组的方法。由于SARS-CoV似乎不会感染小鼠，因此将开发能够感染小鼠的重组SARS-CoV。还将开发将突变引入人类冠状病毒HCoV-OC43(普通感冒的原因)的方法，因为这种病毒的小鼠适应版本已可用。具体目的2.研究HCoV-OC43和重组SARS-CoV在小鼠体内的致病机制。在这一特定的目标下，将研究这些病毒感染小鼠的临床、病理和免疫学影响。具体目的3.评价SARS-CoV特异性蛋白在小鼠发病机制中的作用。将对表达单个SARS-CoV的重组HCoV-OC43进行鉴定。作为这一特定目标的一部分，将在病毒背景下对个别SARS-CoV特异性基因进行基因破坏。这些实验不仅将导致开发一种有用的SARS-CoV动物模型，而且将导致识别参与免疫调节的病毒因子。

Severe Acute Respiratory Syndrome (SARS), a human disease with significant morbidity and mortality, was first recognized in late 2002. Within a few months, a human coronavirus, SARS-CoV was identified as the etiological agent for this disease. Little is known about the pathogenesis of this infection, but several features suggest that the disease is, in part, immunopathological. In contrast, much more is known about mechanisms of coronavirus-induced disease in animals. In specific, much has been learned about the immune-mediated demyelinating disease caused by mouse hepatitis virus, a murine coronavims, in large part because useful animal models are available for its study. At present, only non-human primates can be infected experimentally with SARS-CoV. While these animals will be useful for some studies, it would be extremely valuable if a small rodent model could be developed to answer questions about SARS-CoV pathogenesis and also to evaluate therapeutic interventions. Therefore the central objective of this project will be to develop and characterize an animal model for SARSCoV. This objective will be approached in the following specific aims. Specific aim 1. To develop methods to study the SARS-CoV genome, using targeted recombination. Since SARS-CoV does not appear to infect mice, recombinant SARS-CoV able to infect mice will be developed. Methodology will also be developed to introduce mutations into the human coronavirus, HCoV-OC43 (a cause of the common cold) since a mouse-adapted version of this virus is available. Specific aim 2. To characterize the pathogenesls of HCoV-OC43 and of recombinant SARS-CoV in mice. The clinical, pathological and immunological effects of infection of mice with these viruses will be investigated in this specific aim. Specific aim 3. To evaluate SARS-CoVspecific proteins for their role in pathogenesis in the mouse. Recombinant HCoV-OC43 expressing individual SARS-CoV will be characterized. Individual SARS-CoV-specific genes will be genetically disrupted in the context of the virus as part of this specific aim. These experiments will not only result in the development of a useful animal model for SARS-CoV, but will lead to identification of viral factors involved in immunomodulation.