RESEARCH TRAINING IN VIRUS ENTRY STUDIES

细小病毒在包括人类在内的许多动物中引起疾病。B19人细小病毒引起儿童疾病第五病，以及罕见但更严重的成人和胎儿疾病。没有任何细小病毒的感染细胞进入途径被描述。这些研究的目的是确定犬细小病毒（CPV）进入组织培养细胞的感染途径，并利用这些信息了解宿主范围限制的机制。CPV的感染进入途径将通过gtp酶的显性干扰突变体的过表达来剖析，gtp酶在正常内吞运输过程中调节特定步骤。此外，阻断这些步骤的抑制性抗体将被微注射到细胞中，并测定其对病毒传染性的影响。CPV是最近出现的一种致病性细小病毒，由猫泛白细胞减少病毒（FPV）的衣壳蛋白自然突变引起。CPV衣壳上的三个表面区域控制着犬的宿主范围，许多在这些区域发生氨基酸变化的突变体在感染猫细胞的同时失去了感染犬细胞的能力。这些突变体的感染在细胞结合后病毒进入时被阻断，但在病毒DNA复制之前。CPV及其宿主范围突变体在允许或限制细胞系中的感染进入途径的比较可能解释这些衣壳区域在不同宿主中的功能。

Parvoviruses cause disease in many animals, including humans. The B19 human parvovirus causes the childhood disease Fifth Disease, as well as rarer, but more severe diseases of adults and fetuses. The infectious cellular entry pathway has not been described for any parvovirus. The aims of these studies are to define the infectious entry pathway of canine parvovirus (CPV) into tissue culture cells, with the longer range goal of using this information to understand the mechanisms of host range restriction. The infectious entry pathway of CPV will be dissected by overexpression of dominant interfering mutants of GTPases which regulate specific steps during normal endocytic trafficking. Additionally inhibitory antibodies which block these steps will be microinjected into cells and the effect on viral infectivity assayed. CPV is a recently emerged pathogenic parvovirus that arose by natural mutation of the capsid protein of a cat virus, feline panleukopenia virus (FPV). Three surface regions on the CPV capsid control canine host range, and many mutants with amino acid changes within these regions lose the ability to infect canine cells while still infecting feline cells. Infection by these mutants is blocked during viral entry at a point after cell binding, but prior to viral DNA replication. A comparison of the infectious entry pathways of CPV and its host range mutants in permissive or restrictive cell lines may explain how these regions of the capsid function in different hosts.