Investigating the Antiviral Role of STING During Enteric RNA Virus Infection in Drosophila

项目总结： 肠道是防止肠道感染的物理和免疫屏障。 病原体。樱桃实验室使用果蝇作为人体和蚊子肠道的活体模型 了解肠道先天免疫反应以及感染如何影响肠道固有免疫反应 微生物区系的组成。辛德比斯病毒是一种由蚊子传播的病毒，它会传播到 在一顿血餐中，蚊子通过口服传播媒介。我们的初步数据显示果蝇 干扰素基因刺激物(STING)的同源物在体内抗Sindbis病毒 肠子。哺乳动物的刺被内源性产生的环二核苷酸结合而激活 通过环状GMP-AMP合成酶(CGAS)或由细菌外源。哺乳动物cGAS产生一种 结合细菌或DNA病毒胞浆DNA后的环二核苷酸，但未被激活 通过结合RNA。我们的初步数据显示，最接近的cGAS同源基因是抗病毒的 肠道辛德毕斯感染。对果蝇cGAS候选基因的序列分析表明，它缺乏 在哺乳动物cGAS中发现的DNA结合域，表明d-cGAS感觉到非DNA 配基，也许是病毒核糖核酸。元基因组数据显示，果蝇共生细菌 编码CDN合成酶表明微生物区系可以提供外源CDN池来 防止后续病毒感染的基础刺痛活性。事实上，我们的初步数据表明 外源性CDN喂饲缺乏微生物区系的果蝇对肠道Sindbis病毒的保护作用 感染。此外，我们还发现，刺痛蛋白可能通过激活自噬而发挥抗病毒作用。 炎症性核因子-kB活化。 我们假设d-cGAs和微生物组都产生CDN来激活dSTING 通过肠道内依赖感染的自噬来保护自己免受RNA病毒的感染。至 在目标1中对这一假设进行扩展，我们建议确定d-cGAs和CDN在 依赖叮咬的抗病毒防御。此外，在目标2中，我们建议定义该机制 通过刺痛在肠道细胞中起到抗病毒作用。这项工作揭示了古代cGAS的演化- STING防御途径，并定义额外的微生物衍生产品，如CDN， 可能会影响肠道免疫。

Project Summary: The intestine serves as a physical and immune barrier to protect against infection by enteric pathogens. The Cherry lab uses Drosophila as an in vivo model of human and mosquito enteric infection to understand the intestinal innate immune response and how it is influenced by the composition of the microbiota. Sindbis virus is a mosquito-borne virus that is transmitted to mosquito vectors orally during a blood meal. Our preliminary data suggest the Drosophila homologue of Stimulator of Interferon Genes (STING) is antiviral against Sindbis virus within the intestine. Mammalian STING is activated by binding cyclic dinucleotides produced endogenously by cyclic GMP-AMP synthase (cGAS) or exogenously by bacteria. Mammalian cGAS produces a cyclic dinucleotide after binding cytosolic DNA from bacteria or DNA viruses but is not activated by binding RNA. Our preliminary data shows that the closest cGAS ortholog is antiviral against enteric Sindbis infection. Sequence analysis of this Drosophila cGAS candidate reveals it lacks the DNA binding domain found in mammalian cGAS, suggesting that d-cGAS senses a non-DNA ligand, perhaps viral RNA. Metagenomic data reveals that Drosophila commensal bacteria encode CDN synthases indicating that the microbiota could provide an exogenous CDN pool to prime basal STING activity from subsequent viral infection. Indeed, our preliminary data suggests exogenous feeding of CDNs to flies lacking their microbiota protects against enteric Sindbis virus infection. Moreover, we found that STING may be antiviral through the activation of autophagy and inflammatory NF-kB activation. We hypothesize that both d-cGAS and the microbiome produce CDNs that activate dSTING to protect from RNA virus infection through infection-dependent autophagy within the intestine. To expand on this hypothesis in Aim 1 we propose to determine the role of d-cGAS and CDNs in STING-dependent antiviral defense. Additionally, in Aim 2 we propose to define the mechanism by which STING is antiviral in enterocytes. This work sheds light on evolution of the ancient cGAS- STING defense pathway and defines how additional microbiota-derived products, such as CDNs, may influence intestinal immunity.