Non‐enveloped RNA viruses pervade all domains of life. In a cell, they co‐assemble from viral RNA and capsid proteins. Virus‐like particles can form in vitro where virtually any non‐cognate polyanionic cargo can be packaged. How only viral RNA gets selected for packaging in vivo, in presence of myriad other polyanionic species, has been a puzzle. Through a combination of charge detection mass spectrometry and cryo‐electron microscopy, it is determined that co‐assembling brome mosaic virus (BMV) coat proteins and nucleic acid oligomers results in capsid structures and stoichiometries that differ from the icosahedral virion. These previously unknown shell structures are strained and less stable than the native one. However, they contain large native structure fragments that can be recycled to form BMV virions, should a viral genome become available. The existence of such structures suggest the possibility of a previously unknown regulatory pathway for the packaging process inside cells.

中文翻译：

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病毒组装途径：偏离但不会太远

无包膜 RNA 病毒遍及生命的所有领域。在一个细胞中，它们由病毒 RNA 和衣壳蛋白共同组装而成。病毒样颗粒可以在体外形成，几乎可以包装任何非同源聚阴离子货物。在无数其他聚阴离子物种存在的情况下，如何仅选择病毒 RNA 进行体内包装一直是个谜。通过电荷检测质谱和低温电子显微镜的结合，确定共组装溴花叶病毒 (BMV) 外壳蛋白和核酸寡聚体导致衣壳结构和化学计量不同于二十面体病毒粒子。这些以前未知的壳结构比天然的壳结构变形且稳定性差。然而，如果病毒基因组可用，它们含有大的天然结构片段，可以再循环形成 BMV 病毒粒子。