Norovirus regulation via bacterial modulation of interferon-lambda

项目概要/摘要 诺如病毒是全球流行性胃肠炎的主要原因，但缺乏有效的疫苗或 抗病毒治疗感染后，病毒可以慢性脱落数周至数月，可能导致 未来的爆发。持续性诺如病毒感染的小动物模型显示， 微生物组增强诺如病毒感染。干扰素-λ（IFN-λ）是一种先天性免疫细胞因子， 在这一过程中，通过一个不明确的机制发挥重要作用。IFN-λ刺激肠道抗病毒信号传导 上皮细胞，在体内被持续性诺如病毒感染的相同细胞，并且可以预防或治愈感染。 因此，共生细菌可能通过阻止宿主对病毒的IFN-λ应答来促进诺如病毒感染。 最近的数据还显示，免疫功能低下小鼠中微生物群落的改变与以下因素有关： 过量的IFN-λ和诺如病毒抗性。这些发现的一个统一假设是， 减少或增强肠上皮细胞产生IFN-λ以调节诺如病毒的能力。 鉴定促进诺如病毒的特定肠道细菌对于了解体内 病毒调节稀释粪便移植和定殖实验揭示了一种有前途的细菌 候选者;将该候选者与不促进诺如病毒的相关种属进行比较， 决定病毒感染的细菌表型特征。这种细菌对特定的 代谢物，以及评估其在体内接近诺如病毒感染的细胞的定位，将被 探讨了该提案还将评估这种候选细菌如何调节诺如病毒允许的簇细胞。 初步数据表明，细菌产物在体外阻止诺如病毒诱导IFN-λ。记者老鼠会 用于测定细菌对干扰素信号传导和病毒感染的体内调节。的机制 哪些细菌改变了对病毒的转录反应也将在一种新的体外肠内 上皮细胞模型最后，免疫功能低下小鼠的粪便因子赋予诺如病毒抗性， 转移，并与过量的IFN-λ和改变肠道细菌相关。IFN-λ在这种病毒中的作用 将使用缺乏IFN-λ受体的小鼠品系测试耐药性，并将转移因子 通过处理转移的材料和检测候选分离株进行鉴定。因为免疫功能低下的小鼠 具有广泛的适应性免疫缺陷，将测试不同的适应性免疫因子对免疫缺陷的调节。 微生物组和可转移因子。 完成这一建议将提供机制的理解，以调节肠道先天性 免疫信号传导和诺如病毒感染。这些研究将揭示细菌与 对肠上皮细胞的调节作用，以适应益生菌对抗肠道病毒的策略。

PROJECT SUMMARY/ABSTRACT Norovirus is the leading cause of epidemic gastroenteritis worldwide, but lacks an effective vaccine or antiviral treatment. After infection, virus can be shed chronically for weeks to months, potentially contributing to future outbreaks. A small animal model for persistent norovirus infection revealed that the commensal bacterial microbiome enhances norovirus infection. Interferon-lambda (IFN-λ), an innate immune cytokine, plays an important role in this process via an unclear mechanism. IFN-λ stimulates antiviral signaling on intestinal epithelial cells, the same cells infected by persistent norovirus in vivo, and can prevent or cure infection. Commensal bacteria may therefore promote norovirus infection by preventing host IFN-λ responses to virus. Recent data also revealed that altered microbial communities in immunocompromised mice are associated with excessive IFN-λ and norovirus resistance. A unifying hypothesis for these findings is that specific bacteria diminish or enhance the capacity of intestinal epithelial cells to generate IFN-λ to regulate norovirus. Identification of specific commensal bacteria that promote norovirus is critical to understanding in vivo viral regulation. Dilutional fecal transplants and colonization experiments revealed a promising bacterial candidate; comparison of this candidate to a related species that does not promote norovirus will highlight bacterial phenotypic characteristics determining viral infection. The effects of this bacteria on specific metabolites, as well as assessment of its localization in proximity to norovirus-infected cells in vivo, will be explored. This proposal will also evaluate how this candidate bacteria regulates norovirus-permissive tuft cells. Preliminary data indicates that bacterial products prevent IFN-λ induction by norovirus in vitro. Reporter mice will be used to assay in vivo regulation of interferon signaling and viral infection by bacteria. The mechanisms by which bacteria alter transcriptional responses to virus will also be interrogated in a novel in vitro intestinal epithelial cell model. Finally, a fecal factor in immunocompromised mice confers norovirus resistance when transferred, and correlates with excessive IFN-λ and altered intestinal bacteria. The role of IFN-λ in this viral resistance will be tested using mouse lines lacking the IFN-λ-receptor, and the transferable factor will be identified by treating transferred material and testing candidate isolates. Because the immunocompromised mice have broad adaptive immune defects, different adaptive immune factors will be tested for their regulation of the microbiome and the transferable factor. Completion of this proposal will provide mechanistic understanding into the regulation of intestinal innate immune signaling and norovirus infection by commensal bacteria. These studies will reveal bacteria with modulatory effects on the intestinal epithelium to adapt for probiotic strategies to combat enteric viruses.