BIOCHEMISTRY OF CCR5/CXCR4/GP120 SIGNAL TRANSDUCTION

本提案旨在解决目前关于趋化因子及其受体在病毒性疾病发病机制中的作用的两个假设。第一种假设是趋化因子受体具有离散的结构特征，可以识别gp120分子上的构象保护特征（在CD4结合后暴露）。该结合位点的相互作用直接导致gp41介导的融合事件。第二种假设是，对病毒感染细胞作出反应的趋化因子是通过以协调的方式招募特定宿主防御细胞来形成免疫反应所必需的。在HIV-1感染的情况下，鉴定肺中的趋化因子反应可能对理解感染的肺部后果具有重要意义。提出了两个具体目标，作为收集有关这些假设的额外信息的手段。目的1将从噬菌体展示文库中鉴定和表征特异性识别gp120/CD4复合物的单链抗体，以更精确地鉴定R5和X4包膜糖蛋白的共受体结合位点。目的2将利用携带诱导型趋化因子拮抗剂或缺乏Th1极化受体CXCR3的转基因小鼠，研究趋化因子在肺部病毒宿主防御中的作用。在这项建议中收集的信息可能对制定控制艾滋病毒疾病的治疗策略具有重要意义。

This proposal seeks to address two current hypotheses regarding the role of chemokines and their receptors in viral disease pathogenesis. The first hypothesis is that the chemokine receptors bear discrete structural features which recognize the bind a conformationally protected feature on the gp120 molecule (exposed after CD4 binding). Interaction at this binding site directly leads to the fusion event mediated by gp41. The second hypotheses is that chemokines responding to virally infected cells are essential to shape the immune response by recruitment of specific host defense cells in a coordinated fashion. In the case of HIV-1 infection, identification of the chemokine response in the lung may be of significance in understanding the pulmonary consequences of the infection. Two specific aims are proposed as means to gather additional information regarding these hypotheses. Aim 1 will identify and characterize single chain antibodies from a phage display library which specifically recognize the gp120/CD4 complex in an effort to identify more precisely the co-receptor binding sites for R5 and X4 envelope glycoproteins. Aim 2 will examine the role of chemokines in viral host defense in the lung using a transgenic mouse bearing an inducible chemokine antagonist or lacking a Th1 polarized receptor CXCR3. Information gathered in this proposal may be of importance in the development of therapeutic strategies to control HIV disease.