Zhang Haonan, Wang Haina, Li Yan, Fan Yunxuan, Zhang Zhenfeng, Chen Hongyu, Song Kai, Huang Li, Zhu Ping
Key Laboratory of Epigenetic Regulation and Intervention, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Adv. 2025 Jul 18;11(29):eadv7326. doi: 10.1126/sciadv.adv7326.
Archaeal viruses are well known for their diverse morphologies and extreme stability. Here, we used cryo-electron tomography to analyze the structure of ellipsoid virus 1 (SEV1), an archaeal virus with an ellipsoidal shape and a lipid envelope, and its infection strategy. We show that the SEV1 nucleocapsid adopts a "coil-stacking" architecture with substantial flexibility. The major capsid protein VP4, whose homologs are widespread in the thermoacidic environments around the Pacific Rim, binds genomic DNA in the formation of a nucleoprotein filament with a "beads-on-a-string" appearance. The virion is notably stable at high temperature and acidic pH, and the envelope of SEV1 is crucial to the thermostability of the virion. The infected cell undergoes cytoplasmic condensation to form patches associated with the assembly intermediates of the progeny virions. The nascent virions are released through virus-associated pyramids (VAPs), which are constructed of an SEV1 protein distinctly different at the amino acid sequence level from other known VAP proteins.
古菌病毒以其多样的形态和极高的稳定性而闻名。在此，我们使用冷冻电子断层扫描技术分析了椭圆病毒1（SEV1）的结构及其感染策略，SEV1是一种具有椭圆形形态和脂质包膜的古菌病毒。我们发现，SEV1核衣壳采用具有显著灵活性的“线圈堆叠”结构。主要衣壳蛋白VP4的同源物广泛存在于环太平洋地区的热酸性环境中，它在形成具有“串珠”外观的核蛋白细丝时与基因组DNA结合。该病毒粒子在高温和酸性pH条件下具有显著的稳定性，并且SEV1的包膜对于病毒粒子的热稳定性至关重要。受感染的细胞会发生细胞质浓缩，形成与子代病毒粒子组装中间体相关的斑块。新生病毒粒子通过病毒相关金字塔结构（VAPs）释放，VAPs由一种在氨基酸序列水平上与其他已知VAP蛋白明显不同的SEV1蛋白构成。
