Ebola and Marburg viruses are filoviruses: filamentous, enveloped viruses that cause haemorrhagic fever. Filoviruses are within the order Mononegavirales, which also includes rabies virus, measles virus, and respiratory syncytial virus. Mononegaviruses have non-segmented, single-stranded negative-sense RNA genomes that are encapsidated by nucleoprotein and other viral proteins to form a helical nucleocapsid. The nucleocapsid acts as a scaffold for virus assembly and as a template for genome transcription and replication. Insights into nucleoprotein–nucleoprotein interactions have been derived from structural studies of oligomerized, RNA-encapsidating nucleoprotein, and cryo-electron microscopy of nucleocapsid or nucleocapsid-like structures. There have been no high-resolution reconstructions of complete mononegavirus nucleocapsids. Here we apply cryo-electron tomography and subtomogram averaging to determine the structure of Ebola virus nucleocapsid within intact viruses and recombinant nucleocapsid-like assemblies. These structures reveal the identity and arrangement of the nucleocapsid components, and suggest that the formation of an extended α-helix from the disordered carboxy-terminal region of nucleoprotein-core links nucleoprotein oligomerization, nucleocapsid condensation, RNA encapsidation, and accessory protein recruitment.

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埃博拉病毒核衣壳的结构和组装

埃博拉病毒和马尔堡病毒是filoviruses：导致出血热的丝状包膜病毒。丝状病毒属于Mononegavirales，也包括狂犬病病毒，麻疹病毒和呼吸道合胞病毒。Mononegagavirus病毒具有无节段的单链负义RNA基因组，被核蛋白和其他病毒蛋白包裹，形成螺旋核衣壳。核衣壳充当病毒组装的支架，并充当基因组转录和复制的模板。核蛋白与核蛋白相互作用的见解来自寡聚化，RNA衣壳化的核蛋白的结构研究，以及核衣壳或核衣壳样结构的冷冻电子显微镜检查。没有完整的单负病毒核衣壳的高分辨率重建。在这里，我们应用低温电子层析成像和子断层图平均法来确定完整病毒和重组核衣壳样装配体内的埃博拉病毒核衣壳结构。这些结构揭示了核衣壳组分的身份和排列，并表明从核蛋白核心的无序羧基末端区域形成扩展的α-螺旋连接了核蛋白寡聚，核衣壳缩合，RNA衣壳化和辅助蛋白募集。