MYOCARDITIS--RECEPTORS FOR A CARDIOTROPIC VIRUS

病毒性心肌炎被认为启动了 在美国导致近9000人死于扩张型心肌病 年。与靶细胞上表达的受体分子的结合是 病毒生命周期的关键第一步，以及表达 特异性受体是病毒嗜性的重要决定因素 特别的纸巾。 柯萨奇B组病毒是病毒性心肌炎的主要病原体。我们有 确定了这些病毒的两个受体。在早期的工作中，我们展示了 衰变加速因子(DAF)，作为依恋受体 病毒株的一个子集。我们现在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 以及所有六种柯萨奇B型病毒的感染。虽然这项提议 与柯萨奇病毒有关，这也是有趣的 作为腺病毒的受体，另一个病毒组 与心肌炎有关。 在这里提出的工作中，我们将定义 对于柯萨奇病毒与DAF和CAR的相互作用很重要，使用 冷冻电子显微镜、定点突变和x射线 结晶学技术我们还将研究早期事件在 与每个感受器相连后的感染。 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，来定义它们之间的关系 病毒嗜性和受体表达。基于Northern杂交分析， 结果表明，CAR基因在原发灶中优先表达。 柯萨奇病毒感染的目标器官。因为一辆老鼠车的同源物 在小鼠中起柯萨奇病毒受体的作用，我们还将使用 小鼠模型，包括转基因和基因敲除动物，以定义 柯萨奇受体在病毒致病中的作用。

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.