Schmidtke Danica T, Hickey Angela S, Wirbel Jakob, Lin Jordan D, Liachko Ivan, Sherlock Gavin, Bhatt Ami S
Department of Microbiology and Immunology, Stanford University, Stanford, CA, USA.
Department of Genetics, Stanford University, Stanford, CA, USA.
Cell Host Microbe. 2025 Aug 13;33(8):1347-1362.e5. doi: 10.1016/j.chom.2025.07.004. Epub 2025 Jul 28.
The prototypic crAssphage (Carjivirus communis) is an abundant, prevalent, and persistent human gut bacteriophage, yet it remains uncultured and its lifestyle uncharacterized. C. communis does not readily plaque, suggesting a largely non-lytic lifestyle. Here, we find that C. communis is a linear phage-plasmid that stably persists extrachromosomally within its host. Plasmid and phage-related genes are transcribed, and multiple putative replication origins may initiate replication for multiple lifestyles and genome conformations, including both circular and linear formations. Leveraging these findings, we use a plaque-free culturing approach to measure C. communis replication on prevalent gut bacteria, notably Phocaeicola vulgatus, P. dorei, and Bacteroides stercoris, revealing a broad host range. C. communis persists without causing major cell lysis events or integrating into host chromosomes. Taken together, C. communis' ability to switch between phage and plasmid lifestyles within a wide range of hosts may contribute to its widespread presence in human gut microbiomes.
典型的crAssphage（普通卡吉病毒）是一种丰富、普遍且持久存在的人类肠道噬菌体，但它仍未被培养，其生活方式也未得到表征。普通卡吉病毒不易形成噬菌斑，这表明其生活方式在很大程度上是非裂解性的。在这里，我们发现普通卡吉病毒是一种线性噬菌体 - 质粒，它在宿主细胞内以染色体外的形式稳定存在。质粒和噬菌体相关基因被转录，多个假定的复制起点可能启动多种生活方式和基因组构象的复制，包括环状和线性形式。利用这些发现，我们采用无噬菌斑培养方法来测量普通卡吉病毒在常见肠道细菌（特别是沃氏嗜胆菌、多雷嗜胆菌和粪拟杆菌）上的复制情况，结果显示其宿主范围广泛。普通卡吉病毒持续存在，不会引发重大细胞裂解事件，也不会整合到宿主染色体中。综上所述，普通卡吉病毒在广泛的宿主范围内在噬菌体和质粒生活方式之间切换的能力，可能有助于其在人类肠道微生物群中广泛存在。
