Defining the role of microbiota-derived cyclic dinucleotides in priming antiviral immune defenses.

肠道病原体是一类主要的致病因子，必须克服物理和环境因素。 胃肠道的免疫屏障。常驻微生物群具有大量配体 和病原体相关分子模式（PAMP），可以通过模式启动免疫防御 识别受体（PRR），位于肠上皮细胞和免疫驻留细胞上。事实上，微生物衍生的 TLR 配体对于肠道屏障和免疫稳态的发育和维持是必需的。 此外，微生物群不是静态的，细菌群落不平衡，称为菌群失调，会影响免疫力， 特别是在老化过程中。衰老与肠道病原体的易感性增加有关，以及如何 失调微生物群改变易感性的情况在很大程度上尚不清楚。微生物衍生配体的补充 被感知到的并且可以启动抗病毒免疫力的能力是不完整的。更好地了解分子 维持免疫力的机制、微生物群和上皮细胞如何相互作用以及这如何影响 感染和发病机制有可能揭示治疗肠道病毒感染的新策略。研究 探索微生物群和宿主基因在肠道感染衰老过程中的作用具有挑战性 由于成本和技术障碍，在小动物模型中。克服我们在分子知识方面的差距 控制肠道病毒感染的机制，我们利用强大的 遗传模型生物，果蝇。我们发现肠道对感染具有很高的屏障：年轻的野生型 苍蝇对人类病毒的口服攻击具有抵抗力，而接种到体腔中时，会绕过 肠道，导致严重感染。肠道中的抗病毒途径谱以及微生物群如何作用 肠道中免疫力的形成尚不完全清楚。初步发现，果蝇 STING 控制肠道感染； dSTING 突变体更容易受到肠道病毒感染。刺痛是已知的 被环状二核苷酸（CDN）激活。虽然 cGAS 可以内源性地产生 CDN，但 STING 也可以 被细菌衍生的 CDN 激活。这促使我们探索共生细菌衍生的可能性 CDN 可能通过 STING 影响肠道的先天防御，因为众所周知，微生物群衍生的 CDN 存在于肠道中。我们的新数据确定了微生物群衍生的 CDN 在抗病毒防御中的作用。消融 幼年动物体内的微生物群会导致感染增加，并且喂养这些微生物群缺陷的果蝇 CDN 具有保护性。在目标 1 中，我们将定义 dSTING 在抗病毒防御中的作用，在目标 2 中，我们将定义该作用 共生源 CDN 在年轻和年老动物抗病毒防御中的作用。

Enteric pathogens represent a major group of disease-causing agents, and must overcome the physical and immunological barrier of the gastrointestinal tract. The resident microbiota presents with a large array of ligands and pathogen-associated molecular patterns (PAMPs) which can prime immune defenses, through pattern recognition receptors (PRRs), both on enterocytes and immune resident cells. Indeed, microbial-derived TLR ligands are necessary for the development and maintenance of the intestinal barrier and immune homeostasis. Moreover, the microbiota is not static and imbalanced bacterial communities, termed dysbiosis, impact immunity, in particular during aging. Aging is associated with increased susceptibility to enteric pathogens, and how the dysbiotic microbiota alters susceptibility is largely unknown. The complement of microbial-derived ligands that are sensed and that can prime antiviral immunity is incomplete. A better understanding of the molecular mechanisms by which immunity is maintained, how the microbiota and epithelia interact, and how this impacts infection and pathogenesis has the potential to reveal novel strategies to treat enteric viral infections. Studies exploring the role of the microbiota and host genes in the context of aging in enteric infections are challenging in small animal models due to costs and technical hurdles. To overcome our gap in knowledge of the molecular mechanisms that control enteric viral infection, we developed an oral model of infection using the powerful genetic model organism, Drosophila. We found that the gut presents a high barrier to infection: young wild type flies are refractory to oral challenge with human viruses, while inoculation into the body cavity, which bypasses the gut, results in robust infection. The spectrum of antiviral pathways engaged in the gut, and how the microbiota shapes immunity in the intestine is incompletely understood. Preliminarily, we found that Drosophila STING controls infection in the intestine; dSTING mutants are more susceptible to enteric viral infection. STING is known to be activated by cyclic dinucleotides (CDNs). While cGAS can produce CDNs endogenously, STING can also be activated by bacterially derived CDNs. This led us to explore the possibility that commensal bacteria-derived CDNs may impact innate defenses in the gut through STING, as it is known that microbiota-derived CDNs are present in the gut. Our new data identifies a role for microbiota-derived CDNs in antiviral defense. Ablation of the microbiota in young animals leads to increased infection, and feeding these microbiota-deficient flies CDNs was protective. In Aim 1 we will define the role of dSTING in antiviral defense and in Aim 2 we will define the role of commensal-derived CDNs in antiviral defense in young and old animals.