非病毒科的噬菌体,或者病毒,是以前通过促进生物膜形成而与细菌发病机理有关的特征不足的噬菌体,免疫逃避,和毒素分泌。不像大多数噬菌体,病毒不会裂解它们的宿主细胞来释放新的后代病毒粒子;相反,它们编码一个分泌系统,主动将它们从细菌细胞中抽出。迄今为止,尚未分离或表征与人类肠道微生物组相关的病毒。
在这项研究中,我们利用了硅片,在体外,和体内方法来检测肠道微生物群的细菌成员中的病毒。通过筛选肠道共生的代表性基因组文库,我们在肠浮菌属中检测到病毒原病毒。(以前是梭菌属。).我们使用成像和qPCR证实了这些生物体的体外培养物中病毒颗粒的分泌。为了评估肠道非生物环境,细菌生理学,和病毒的分泌可能有联系,我们部署了一项三方体外试验,逐步评估细菌生长动力学,生物膜的形成,和在渗透环境变化的情况下分泌病毒。对抗其他产内病毒的细菌,肠浮菌属病毒的产生与生物膜的形成无关。相反,肠浮菌菌株对与肠道生理相关的渗透压水平变化具有异质性反应。值得注意的是,以毒株依赖性方式增加渗透压诱导的病毒分泌。我们证实了在未受干扰的条件下在体内接种单个肠浮菌菌株的生性小鼠模型中的病毒分泌。此外,与我们的体外观察一致,由于渗透性泻药,肠道中渗透环境的变化调节了病毒的分泌。
在这项研究中,我们报告了从肠球藻属的肠道共生中检测到的新型病毒的特征。一起,我们的结果证明人类肠道相关细菌可以分泌病毒,并开始阐明共生细菌中病毒填充的环境生态位。视频摘要。
Bacteriophages in the family Inoviridae, or inoviruses, are under-characterized phages previously implicated in bacterial pathogenesis by contributing to biofilm formation, immune evasion, and toxin secretion. Unlike most bacteriophages, inoviruses do not lyse their host cells to release new progeny virions; rather, they encode a secretion system that actively pumps them out of the bacterial cell. To date, no inovirus associated with the human gut microbiome has been isolated or characterized.
In this study, we utilized in silico, in vitro, and in vivo methods to detect inoviruses in bacterial members of the gut microbiota. By screening a representative genome library of gut commensals, we detected inovirus prophages in Enterocloster spp. (formerly Clostridium spp.). We confirmed the secretion of inovirus particles in in vitro cultures of these organisms using imaging and qPCR. To assess how the gut abiotic environment, bacterial physiology, and inovirus secretion may be linked, we deployed a tripartite in vitro assay that progressively evaluated bacterial growth dynamics, biofilm formation, and inovirus secretion in the presence of changing osmotic environments. Counter to other inovirus-producing bacteria, inovirus production was not correlated with biofilm formation in Enterocloster spp. Instead, the Enterocloster strains had heterogeneous responses to changing osmolality levels relevant to gut physiology. Notably, increasing osmolality induced inovirus secretion in a strain-dependent manner. We confirmed inovirus secretion in a gnotobiotic mouse model inoculated with individual Enterocloster strains in vivo in unperturbed conditions. Furthermore, consistent with our in vitro observations, inovirus secretion was regulated by a changed osmotic environment in the gut due to osmotic laxatives.
In this study, we report on the detection and characterization of novel inoviruses from gut commensals in the Enterocloster genus. Together, our results demonstrate that human gut-associated bacteria can secrete inoviruses and begin to elucidate the environmental niche filled by inoviruses in commensal bacteria. Video Abstract.