EARLY STAGES OF INFECTION BY NONENVELOPED VIRUSES

描述：人脊髓灰质炎病毒受体（PVR）的表征导致 详细描述了进入过程的初始阶段， 病毒-受体相互作用 然而，动力学和遗传学证据也 表明存在涉及膜的额外阶段 相互作用，仍然知之甚少。 在这一修改后的申请，博士。 阿肯色州大学的Chow和她的合作者M.托斯特森在 哈佛大学，将评估两个合理的模型，RNA交付到 细胞质 这两种模型都要求原生（160 S）粒子相互作用 与PVR产生“进入活性”颗粒，这改变了 颗粒与宿主细胞膜相互作用。 最简单的模型提出 在PVR相互作用后，只有RNA基因组被直接转运， 通过病毒特异性离子渗透通道穿过质膜。 第二种模式涉及“传递活跃”病毒的通过 颗粒穿过细胞膜进入细胞质，随后释放 从粒子中提取RNA 为了剖析这些早期事件， 研究将建立在Chow博士和Tosteson最近的观察基础上， 感受态病毒在模型膜中产生离子渗透通道。 在 第一个目的，申请人提出表征电导、动力学 通道的特性和管腔尺寸。 他们还将分别 确定对接病毒颗粒对通道形成的影响 使用PVR对比使用Fc受体与抗体包被的颗粒。 他们还将监测粒子通道形成过程中引起的效应 结合Win药物或肽特异性抗体的特性。 的 第二个目标将表征参与膜的衣壳蛋白结构域 交互并定义它们在病毒进入中的角色。 现有的和新 在VP 4或VP 1的N-末端构建进入缺陷突变体 将使用模型膜检查通道中的任何变化 如果发现，这些特性将与生物表型相关。 预计这些研究将提供生物化学和 生物物理组成的通道结构，并允许申请人 建立无包膜感染早期阶段的一般模型 病毒

DESCRIPTION: Characterization of human poliovirus receptor (PVR) has led to a detailed description of the initial stage of the entry process, the virus-receptor interaction. However, kinetic and genetic evidence also indicate the existence of additional stages which involve membrane interactions and remain poorly understood. In this revised application, Dr. Chow at the University of Arkansas and her collaborator, Dr. M. Tosteson at Harvard, will evaluate two plausible models of RNA delivery into the cytoplasm. Both models require that the native (160S) particles interact with PVR to generate an "entry-active" particle and that this altered particle interacts with host cell membranes. The simplest model proposes that, after PVR interaction, only the RNA genome is transported directly across the plasma membrane through virus-specific ion-permeable channels. The second model involves the passage of the "delivery active" virus particle across the membrane into the cytoplasm and subsequent release of the RNA from the particle. To dissect these early events, the proposed studies will build on Drs. Chow and Tosteson's recent observation that entry competent viruses produce ion-permeable channels in model membranes. In the first Aim, the applicants propose to characterize conductance, kinetic characteristics and lumen size of the channels. They will also separately determine the effects on channel formation of docking the virus particles using the PVR versus using an Fc receptor with antibody coated particles. They also will monitor effects induced in the particle's channel forming properties from binding Win drugs or peptide specific antibodies. The second Aim will characterize the capsid protein domains involved in membrane interaction and define their roles in virus entry. Existing and newly constructed mutants in VP4 or in the N-terminus of VP1 defective in entry will be examined using model membranes for any changes in channel properties; if found, these will be correlated with biological phenotypes. It is aticipated that the studies will provide the biochemical and biophysical make-up of the channel structure and allow the applicants to build a general model of the early stages of infection by nonenveloped viruses.