CryoEM and image reconstruction of viruses

病毒是寄主的寄生虫。因此，任何病毒的生命周期都与宿主细胞的生命周期密不可分。尽管存在这种依赖性，但所有病毒都有一些生存所必须完成的基本任务。病毒必须能够找到并识别能够在其中复制的细胞，将其基因组释放到细胞中，通过转录和翻译产生新的病毒成分，并将这些成分组装成前体，这些前体成熟为稳定的子代病毒粒子，从宿主细胞释放出来，并通过传播遇到新的宿主。由于适应不同的细胞环境，不同的病毒以不同的方式完成这些任务。这些任务中的每一项都涉及整个病毒粒子范围内各组分之间的相互作用，因此需要对整个结构进行可视化，而低温透射电子显微镜(CryoTEM)和三维(3D)图像重建(“低温重建”)技术在这一点上表现出色。我们利用低温重建技术研究了各种病毒，包括那些感染哺乳动物以及昆虫、细菌和植物(包括真菌和藻类)的病毒。由目前的PPG资助的几项研究说明了不同病毒对病毒生命周期常见任务的结构反应。这项提议涉及几项新的冷冻重建研究，旨在探索病毒感染关键方面的结构基础。与库恩和罗斯曼实验室的合作将继续分析甲型病毒基因(TogaVirus家族)的几种包膜病毒的组装。我们还将启动三种重要的人类致病机制的新研究：风疹病毒(红斑病毒属)和两个密切相关的黄病毒囊膜病毒家族成员，黄热病病毒和丙型肝炎病毒。与史密斯实验室的合作将解决两种植物病毒--黄瓜花叶病毒和西葫芦黄花叶病毒--中的病毒传播问题。与弗里德曼实验室的合作将确定人类乳头状瘤病毒的病毒表位，包括致癌的HPV血清型16。

Viruses are parasites of their hosts. Hence, the life cycle of any virus is inextricably tied to that of the host cell. Despite this dependence, all viruses share a number of essential tasks which they must accomplish for survival. A virus must be able to find and recognize a cell in which it can replicate, release its genome into the cell, generate new viral components by transcription and translation and assembly these components into precursors that mature into a stable progeny virion which is released from the host cell and transmitted to encounter a new host. Different viruses accomplish these tasks in different ways as a result of adaptation to different cellular environments. Each of these tasks involves interactions between components within the context of the whole virion and hence require the visualization of the entire structure at which the techniques of cryo-transmission electron microscopy (cryoTEM) and three-dimensional (3D) image reconstruction ('cryo-reconstruction') excel. We have exploited cryo-reconstruction techniques to study a diverse range of viruses, including those that infect mammals as well as insects, bacteria, and plants (including fungi and algae). Several studies funded by the current PPG have illustrated the structural response of different viruses to the common tasks of the viral life cycle. This proposal involves several new cryo-reconstruction studies aimed at exploring the structural basis for key aspects of viral infection. Work with the Kuhn and Rossmann laboratories will continue analyses of the assembly of several enveloped viruses of the alphavirus gene (Togavirus family). We will also initiate new studies of the assembly of three important human pathogenesis: rubella virus (rubrivirus genus) and two members of the closely related Flavivirus family of enveloped viruses, yellow fever virus and Hepatitis C virus. A collaboration with Smith's laboratory will address issues related to viral transmission in two plant viruses, cucumber mosaic virus and zucchini yellow mosaic virus. A collaboration with Friedman's laboratory will define viral epitopes on human papilloma viruses, including the carcinogenic, HPV serotype 16.