Structure and arrangement of viral proteins in HIV, Marburg and Influenza viruses

病毒颗粒的形成是由病毒结构蛋白组装成规则的晶格驱动的。然而，对于许多包膜病毒，包括人类病原体，如人类免疫缺陷病毒（HIV）、马尔堡病毒和流感病毒，这种有规律的组装导致产生大小和形状高度异质的病毒颗粒。这些病毒使用结合灵活性和可变性的组装机制，允许在异质细胞环境中进行稳健的组装和包膜。这种结构的异质性使研究病毒结构蛋白排列的尝试受挫。因此，目前尚不清楚病毒结构蛋白的结构域是如何排列在重复晶格内的，也不清楚晶格是如何排列形成整个病毒颗粒的。在这里，我们建议将最先进的冷冻电子断层扫描和亚断层扫描平均方法应用于艾滋病毒，马尔堡病毒和流感病毒。在每种情况下，我们都将求解局部病毒蛋白晶格的结构，并绘制蛋白质晶格中每个单个单元细胞在完整病毒颗粒中的位置。在马尔堡病毒的情况下，我们也会对细胞出芽的颗粒这样做。这些实验将回答有关单个病毒的具体结构问题，并揭示这些病毒如何结合规律性和异质性来组装和包膜感染性颗粒的一般原理。

The formation of virus particles is driven by the assembly of viral structural proteins into regular lattices. Nevertheless, for many enveloped viruses, including human pathogens such as Human immunodeficiency virus (HIV), Marburg and Influenza viruses, this regular assembly leads to the production of virus particles that are highly heterogenous in size and shape. These viruses use assembly mechanisms which incorporate flexibility and variability to allow robust assembly and envelopment in the heterogeneous cellular environment. This structural heterogeneity has frustrated attempts to study the arrangement of the viral structural proteins. As a result it is not clear how the domains of the virus structural proteins are arranged within the repeating lattice, or how the lattice is arranged to form a whole virus particle. Here we propose to apply state of the art cryo-electron tomography and sub-tomogram averaging approaches to HIV, Marburg and Influenza viruses. In each case, we will solve the structure of the local viral protein lattice, and map the position of every individual unit cell of the protein lattice in complete virus particles. In the case of Marburg virus, we will also do this for particles budding from cells. These experiments will answer specific structural questions about the individual viruses, and also reveal general principles as to how these viruses combine regularity and heterogeneity to assemble and envelope infectious particles.