Liu Xiaoyu, Xia Xian, Martynowycz Michael W, Gonen Tamir, Zhou Z Hong
Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA, USA.
California NanoSystems Institute, University of California, Los Angeles, CA, USA.
Nat Commun. 2024 Dec 6;15(1):10638. doi: 10.1038/s41467-024-54968-7.
Virus-induced cellular condensates, or viral factories, are poorly understood high-density phases where replication of many viruses occurs. Here, by cryogenic electron tomography (cryoET) of focused ion beam (FIB) milling-produced lamellae of mammalian reovirus (MRV)-infected cells, we visualized the molecular organization and interplay (i.e., "molecular sociology") of host and virus in 3D at two time points post-infection, enabling a detailed description of these condensates and a mechanistic understanding of MRV replication within them. Expanding over time, the condensate fashions host ribosomes at its periphery, and host microtubules, lipid membranes, and viral molecules in its interior, forming a 3D architecture that supports the dynamic processes of viral genome replication and capsid assembly. A total of six MRV assembly intermediates are identified inside the condensate: star core, empty and genome-containing cores, empty and full virions, and outer shell particle. Except for star core, these intermediates are visualized at atomic resolution by cryogenic electron microscopy (cryoEM) of cellular extracts. The temporal sequence and spatial rearrangement among these viral intermediates choreograph the viral life cycle within the condensates. Together, the molecular sociology of MRV-induced cellular condensate highlights the functional advantage of transient enrichment of molecules at the right location and time for viral replication.
病毒诱导的细胞凝聚物，即病毒工厂，是一种人们了解甚少的高密度相，许多病毒在此进行复制。在这里，通过对聚焦离子束（FIB）铣削制备的感染哺乳动物呼肠孤病毒（MRV）细胞薄片进行低温电子断层扫描（cryoET），我们在感染后的两个时间点以三维方式可视化了宿主和病毒的分子组织及相互作用（即“分子社会学”），从而能够详细描述这些凝聚物，并从机制上理解MRV在其中的复制过程。随着时间的推移，凝聚物在其周边塑造宿主核糖体，并在其内部塑造宿主微管、脂质膜和病毒分子，形成一种支持病毒基因组复制和衣壳组装动态过程的三维结构。在凝聚物内部共鉴定出六种MRV组装中间体：星状核心、空的和含有基因组的核心、空的和完整的病毒粒子以及外壳颗粒。除了星状核心外，这些中间体通过对细胞提取物进行低温电子显微镜（cryoEM）观察，以原子分辨率呈现出来。这些病毒中间体之间的时间序列和空间重排编排了凝聚物内的病毒生命周期。总之，MRV诱导的细胞凝聚物的分子社会学突出了在正确的位置和时间对分子进行瞬时富集以利于病毒复制的功能优势。
