SFTSV nonstructural protein NSs-mediated immunopathogenesis

项目摘要/摘要 严重发热伴血小板减少综合征病毒(SFTSV)列入世界卫生组织 组织9最危险的病原体是一种新出现的白喉病毒，属于珍珠病毒科。 由于缺乏针对SFTSV感染的治疗和疫苗，迫切需要 了解SFTSV的发病机制，以开发有效的抗病毒药物。指定为 生物安全3级试剂SFTSV包含一个基因组，由三个阴性或 双目RNA分为大、中、小三种类型。S片段编码一个核蛋白 和非结构蛋白(NSS)通过双链感觉编码策略。(目标1)我们发现 NSS靶向Vps15-Vps34脂蛋白激酶复合体形成病毒诱导的自噬体样 包涵体(IB)，随后隔离干扰素信号效应器(RIG-I、TRIM25和 Tbk1)与IB结合，从而抑制干扰素的产生。(目标2)我们还发现SFTSV NSS通过靶向Tpl2-ABIN2-p105激酶在病毒免疫发病中发挥重要作用 强力诱导免疫抑制基因表达的复合体，特别是IL-10细胞因子。 (目的3)我们结合了病毒反向遗传学、Tpl2-/-和IL10-/-小鼠 NSS介导的Tpl2信号通路激活模型有力地诱导了IL-10 产生对病毒致病至关重要的物质。第一次，我们发展了一个时代-- 依赖雪貂模型：年轻成年雪貂(&lt；2岁)没有表现出任何临床症状和 死亡率；然而，感染SFTSV的老年雪貂(&gt；4岁)表现出严重的 血小板减少，白细胞减少，高烧，死亡率约90%，完全 概括了人类的临床表现。具有良好的体外实验条件 和新的活体动物模型，拟议的研究不仅证明了 SFTSV NSS在病毒免疫逃避和发病机制中的作用，也确定了潜在的治疗方法 猪瘟病毒感染患者的治疗方法。

Project Summary/Abstract Severe fever with thrombocytopenia syndrome virus (SFTSV) listed in the World Health Organization 9 most dangerous pathogens is an emerging Phlebovirus in the Phenuiviridae family. Due to the lack of therapy and vaccine against SFTSV infection, there is a pressing need to understand the pathogenesis of SFTSV to develop effective antiviral agents. Designated as Biosafety level 3 agent, SFTSV contains a genome comprised of three segments of negative or ambisense RNA designated as large, medium, and small. The S segment encodes a nucleoprotein and a nonstructural protein (NSs) via an ambisense coding strategy. (Aim 1) We have discovered that NSs targets the Vps15-Vps34 lipid kinase complex to form virus-induced autophagosome-like inclusion bodies (IB), subsequently sequestrating IFN signaling effectors (RIG-I, TRIM25, and TBK1) to the IB and thereby suppressing IFN production. (Aim 2) We have also found that SFTSV NSs plays an essential role in viral immunopathogenesis by targeting the TPL2-ABIN2-p105 kinase complex to robustly induce expression of immune suppressive genes, specifically IL-10 cytokine. (Aim 3) We combined viral reverse genetics, a TPL2 kinase inhibitor, Tpl2-/- and il10-/- mouse models to show that the NSs-mediated activation of TPL2 signaling pathway robustly induced IL-10 production that was essential for viral pathogenesis. For the first time, we developed an age- dependent ferret model: young adult ferrets (<2 years old) did not show any clinical symptoms and mortality; however, SFTSV-infected aged ferrets (>4 years old) demonstrated severe thrombocytopenia, reduced white blood cells, and high fever with ~90% mortality rate, fully recapitulating human clinical manifestation. With well-established in vitro experimental conditions and novel in vivo animal models, the proposed study not only demonstrates the critical role of SFTSV NSs in viral immune evasion and pathogenesis, but also identifies potential therapeutic approaches to treat SFTSV-infected patients.