MYOCARDITIS--RECEPTORS FOR A CARDIOTROPIC VIRUS

病毒性心肌炎被认为是启动病理过程， 在美国每年有近9,000人死于扩张型心肌病 年 与靶细胞上表达的受体分子的附着是 病毒生命周期中关键的第一步， 特异性受体是病毒嗜性的重要决定因素， 特殊组织。 科萨基B病毒是病毒性心肌炎的主要病原。我们有 发现了两种病毒的受体 在早期的工作中，我们展示了 衰变加速因子（DAF）充当附着受体 病毒株的一个子集。 我们已经提纯并克隆了另一个- --新的-细胞表面蛋白，CAR，既在附着中起作用， 以及所有六种科萨基B血清型的感染。 虽然这一提议 与柯萨奇病毒有关，有趣的是CAR还 作为腺病毒的受体， 与心肌炎有关 在这里提出的工作中，我们将定义结构特征， 是重要的柯萨奇病毒相互作用与ESTA和CAR，使用 冷冻电子显微镜定点突变和X射线 晶体学技术 我们还将研究早期的事件， 与每种受体结合后感染。 此外，我们还将研究受体在人体内的分布， 组织，包括心肌细胞，以确定 病毒嗜性和受体表达。 基于北方印迹分析， 似乎CAR mRNA优先在原发性肝癌中表达， 科萨基感染的靶器官因为鼠CAR同源物 在小鼠中作为柯萨奇病毒受体，我们也将使用 小鼠模型，包括转基因和敲除动物，以定义 科萨基受体在病毒发病机制中的作用。

Viral myocarditis is believed to initiate the pathologic processes that lead to nearly 9,000 deaths from dilated cardiomyopathy in the US each year. Attachment to a receptor molecule expressed on a target cell is a critical first step in the virus life cycle, and expression of specific receptors is and important determinant of virus tropism for particular tissues. Coxsackie B viruses are the major agents of viral myocarditis. We have identified two receptors for these viruses. In earlier work, we showed that decay accelerating factor (DAF), serves as an attachment receptor for a subset of viral strains. We have now purified and cloned another- --novel---cell surface protein, CAR, that functions both in attachment and infection by all six coxsackie B serotypes. Although this proposal is concerned with coxsackieviruses, it is of interest that CAR also functions as the receptor for adenoviruses, another virus group implicated in myocarditis. In the work proposed here, we will define the structural features that are important for coxsackievirus interactions with DAF and CAR, using cryoelectronmicroscopy, site-directed mutagenesis, and x-ray crystallographic techniques. We will also examine the early events in infection that follow attachment to each of the receptors. In addition, we will study the distribution of receptors in human tissues, including cardiac myocytes, to define the relationship between virus tropism and receptor expression. Based on Northern blot analysis, it appears that CAR mRNA is preferentially expressed in the primary target organs for coxsackie infection. Because a murine CAR homologue functions as the coxsackievirus receptor in mice, we will also use murine models, including transgenic and knock-out animals, to define the role of the coxsackie receptor in viral pathogenesis.