The crAss-like phages are ubiquitous and highly abundant members of the human gut virome that infect commensal bacteria of the order Bacteroidales. Although incapable of lysogeny, these viruses demonstrate long-term persistence in the human gut microbiome, dominating the virome in some individuals. Here we show that rapid phase variation of alternate capsular polysaccharides in Bacteroides intestinalis cultures plays an important role in a dynamic equilibrium between phage sensitivity and resistance, allowing phage and bacteria to multiply in parallel. The data also suggests the role of a concomitant phage persistence mechanism associated with delayed lysis of infected cells, similar to carrier state infection. From an ecological and evolutionary standpoint, this type of phage-host interaction is consistent with the Piggyback-the-Winner model, which suggests a preference towards lysogenic or other “benign” forms of phage infection when the host is stably present at high abundance. Long-term persistence of bacteriophage and host could result from mutually beneficial mechanisms driving bacterial strain-level diversity and phage survival in complex environments.

中文翻译：

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crAss 样噬菌体 crAss001 的长期存在与肠道拟杆菌的相位变化有关


类粗噬菌体是人类肠道病毒组中普遍存在且高度丰富的成员，可感染拟杆菌目共生细菌。尽管这些病毒无法溶原，但它们在人类肠道微生物组中表现出长期持续存在，并在某些个体的病毒组中占主导地位。在这里，我们表明，肠道拟杆菌培养物中交替荚膜多糖的快速相变在噬菌体敏感性和耐药性之间的动态平衡中发挥着重要作用，使噬菌体和细菌能够平行繁殖。数据还表明，与感染细胞延迟裂解相关的伴随噬菌体持续机制的作用，类似于携带者状态感染。从生态和进化的角度来看，这种类型的噬菌体-宿主相互作用与“胜者背负”模型一致，该模型表明当宿主以高丰度稳定存在时，倾向于溶原或其他“良性”形式的噬菌体感染。噬菌体和宿主的长期存在可能是由于驱动细菌菌株水平多样性和噬菌体在复杂环境中生存的互利机制所致。