Norovirus regulation via bacterial modulation of interferon-lambda

项目摘要/摘要 诺沃克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，病毒可慢性传播数周至数月，有可能导致 未来的疫情。持续诺沃克病毒感染的小动物模型显示，共生细菌 微生物组可增强诺沃克病毒感染。干扰素-λ是一种天然免疫细胞因子，在 通过一种不清楚的机制在这一过程中发挥重要作用。干扰素-λ刺激肠道抗病毒信号转导 上皮细胞，同样的细胞在体内被持续的诺沃克病毒感染，并可以预防或治疗感染。 因此，共生细菌可能通过阻止宿主干扰素-λ对病毒的反应来促进诺沃克病毒的感染。 最近的数据还显示，免疫受损小鼠体内改变的微生物群落与 干扰素-λ和诺如病毒耐药性过强。对这些发现的一个统一假设是，特定的细菌 降低或增强肠上皮细胞产生干扰素-λ以调节诺如病毒的能力。 识别促进诺如病毒的特定共生菌对了解体内情况至关重要 病毒式监管。稀释性粪便移植和定植实验发现了一种有希望的细菌 候选人；将该候选人与不促进诺沃克病毒的相关物种进行比较将突出 决定病毒感染的细菌表型特征。这种细菌对特异菌的影响 代谢产物，以及对其在体内接近诺沃克病毒感染细胞的定位的评估，将是 探索过了。该提案还将评估这一候选细菌如何调节诺沃克病毒允许的丛生细胞。 初步数据表明，细菌制品在体外可以阻止诺如病毒诱导的干扰素-λ。记者老鼠会 用于检测干扰素信号的体内调节和细菌对病毒感染的调节。这些机制由 哪些细菌会改变对病毒的转录反应也将在一种新的体外肠道中被询问 上皮细胞模型。最后，免疫受损小鼠的粪便因子在以下情况下会产生诺沃克病毒耐药性 转移，并与过量的干扰素-λ和肠道细菌改变相关。干扰素-λ在该病毒中的作用 将使用缺乏干扰素-λ-受体的小鼠品系进行耐药性测试，转移因子将是 通过处理转移的材料和测试候选菌株进行鉴定。因为免疫受损的小鼠 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它们的调节作用 微生物组和可转移因子。 这项建议的完成将提供对肠道先天调节的机械性理解。 共生细菌的免疫信号与诺如病毒感染。这些研究将揭示细菌与 对肠道上皮的调节作用，以适应抗击肠道病毒的益生菌策略。

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.