C19orf66通过溶酶体途径降解柯萨奇病毒蛋白酶而抗病毒及保护血脑屏障的功能及机制研究

柯萨奇病毒（CV）能侵犯神经系统导致无菌性脑膜脑炎等。C19orf66是一个新近发现的ISG，但其针对不同病毒的作用机制不尽相同。我们前期研究发现了CV可诱导宿主细胞及小鼠组织中C19orf66明显上调，并具有较强抑制CV复制的功能。本研究从病毒与宿主互作角度，拟系统性开展C19orf66与CV毒力因子互作关系及其致病性的研究。从分子、细胞、动物水平（血脑屏障模型），拟阐明C19orf66的双重作用分子机制：直接降解病毒蛋白及正反馈激活天然免疫。C19orf66通过与CV蛋白酶2A及3C相互结合，促进两者通过溶酶体途径降解；同时通过激活RIG-I-MAVS通路正反馈调节干扰素产生，从而发挥其高效的抗柯萨奇病毒感染并保护血脑屏障的新功能。通过回答上述科学问题，不仅对揭示CV的神经系统致病机理有重要意义，而且从病毒与宿主天然免疫系统互作角度，为抗柯萨奇病毒药物的研发提供科学理论基础。

The rapidly emerging human health crisis associated with the coxsackievirus (CV) epidemic and its link to severe complications highlights the growing need to identify the mechanisms by which CV accesses hosts. Interferon response protects host cells against viral infection, while the cellular factors that mediate this defense are the products of interferon-stimulated genes (ISGs). Although hundreds of ISGs have been identified, only a few have been characterized for their antiviral potential, target specificity and mechanisms of action. In this work, we focused our investigation on the possible antiviral effect of a novel ISG, C19orf66 in response to CV infection and the associated mechanisms. Recently, our preliminary results demonstrated that CV infection could induce C19orf66 expression in CV-permissive cells or in mouse model, and such an overexpression of C19orf66 remarkably suppressed CV replication. Conversely, the depletion of C19orf66 led to a significant increase in viral replication. Therefore, in the current project, firstly, we are aiming to our novel finding of the anti-CV effect of C19orf66, and its underlying mechanisms, which is was found to interact and co-localize with CV nonstructural protein 2A and 3C (viral protease), thus inducing 2A and 3C degradation via a lysosome-dependent pathway. Secondly, we are aiming to demonstrate the molecular mechanism of CV-mediated innate immunity activation by which C19orf66 promotes the formation of RIG-I-MAVS complexes, activates the signal transduction, and ultimately triggers type I interferon production, and the process is a positive feedback loop. Lastly, we are aiming to show that systemic spread of CV from the site of infection to the brain requires IFN signaling deficiency triggered by C19orf66. Within this context of C19orf66 deletion, CV infection of brain microvascular endothelial cell and astrocytes results in breakdown of the blood-brain barrier. Taken together, the aim of this project is to identify C19orf66 as a novel ISG that exerts antiviral effects against CV by specifically degrading a viral nonstructural protein and promoting IFN signaling in feedback manner. These findings uncovered an intriguing mechanism of C19orf66 that directly targeting 2A and 3C protein of CV, providing clues for understanding the neuropathogenesis of CV, and the actions of innate immunity, and affording the possible availability of new drug targets that can be used for therapeutic intervention.