Host genetic determinants of neuroinvasive flavivirus pathogenesis

项目总结 鲍瓦桑病毒(Powassan Virus，POWV)是一种新出现的硬虱传播的神经侵袭性黄病毒。类似于蚊媒传播 黄病毒，如西尼罗河病毒和日本脑炎病毒，POWV导致神经侵袭性疾病， 包括脑炎、脑膜炎、瘫痪和死亡。而大多数黄病毒感染会导致 无症状感染，一组有症状的黄病毒感染进展为神经侵袭性疾病， 尽管影响严重疾病易感性的因素还不完全清楚，人们对此知之甚少 POWV的致病机制。我们假设宿主抗病毒反应基因的变异 有助于区分黄病毒感染后的疾病结局。我们建议使用协作交叉 (CC)小鼠鉴定POWV致病特征并识别与POWV有关的宿主基因 敏感度。CC是重组近交系小鼠的小鼠遗传参考群体，由 杂交了代表三个野生来源和五个经典实验室小鼠品系的八个方正品系。消委会 以可重复的方式捕获实验室小鼠的遗传多样性，因为~80个品系中的每一个都有一个 已知和固定的基因组，为绘制复杂性状图谱提供了宝贵的工具。在初步研究中，我们感染了 一组Oas1b缺失的CC小鼠患有POWV，并观察到一系列易感表型，提示 除了特征明确的黄病毒限制因子Oas1b之外，还有其他宿主因素调节POWV 小鼠的发病机制。我们鉴定了多个高度感病的品系(100%致死)，包括CC071和一个 单抗品系(0%致死率)，CC045。在此初步数据的基础上，我们建议i)确定病毒和 POWV在易感和抗性CC株系中致病的免疫学特征，以及II)MAP定量 利用感病和抗病品系的F2代检测与POWV致病相关的QTL。在……里面 目的1，我们将评估POWV感染后中枢神经系统的病毒载量和渗透的白细胞，特征 POWV在原代细胞中的复制，并评估血脑屏障通透性，使用易感(CC071)和 抗性(CC045)CC品系。在目标2中，我们将评估POWV致死率、病毒载量和浸润性白细胞。 并定位与这些表型相关的QTL，以确定寄主遗传元件 对POWV易感性有贡献。建议的研究将进一步加深我们对黄病毒神经侵袭的理解。 通过鉴定宿主遗传因素调节小鼠对POWV的易感性并提供 对更广泛地影响神经侵袭性黄病毒的因素的洞察。拟议的培训计划将重点放在 建立数量遗传学技术研究猪传染性支气管炎病毒和免疫学机制 POWV发病机制，并将为我的职业生涯做好准备，成为一名使用数量遗传学的独立研究人员 研究传染病的技术。

PROJECT SUMMARY Powassan virus (POWV) is an emerging tick-borne neuroinvasive flavivirus. Similar to mosquito-borne flaviviruses such as West Nile virus and Japanese encephalitis virus, POWV causes neuroinvasive disease, including encephalitis, meningitis, paralysis, and death. While the majority of flavivirus infections result in asymptomatic infection, a subset of symptomatic flavivirus infections progress to neuroinvasive disease, although the factors influencing susceptibility to severe disease are not fully understood and little is known about the pathogenic mechanisms of POWV. We hypothesize that variation in host antiviral response genes contributes to differential disease outcome following flavivirus infection. We propose to use Collaborative Cross (CC) mice to characterize features of POWV pathogenesis and identify host genes that contribute to POWV susceptibility. The CC is a mouse genetic reference population of recombinant inbred mice generated by crossing eight founder lines that represent three wild-derived and five classical laboratory mouse lines. The CC captures the genetic diversity of laboratory mice in a reproducible manner, since each of the ~80 lines has a known and fixed genome, providing a valuable tool for mapping complex traits. In preliminary studies, we infected a panel of Oas1b-null CC mouse lines with POWV and observed a range of susceptibility phenotypes, suggesting there are host factors other than the well-characterized flavivirus restriction factor Oas1b that modulate POWV pathogenesis in mice. We identified multiple highly susceptible lines (100% lethality), including CC071, and a single resistant line (0% lethality), CC045. Building on this preliminary data, we propose to i) determine viral and immunologic features of POWV pathogenesis in susceptible and resistant CC lines, and ii) map Quantitative Trait Loci (QTL) associated with POWV pathogenesis using F2 progeny of susceptible and resistant lines. In Aim 1, we will evaluate viral loads and infiltrating leukocytes in the CNS following POWV infection, characterize POWV replication in primary cells, and assess blood-brain barrier permeability, using susceptible (CC071) and resistant (CC045) CC lines. In Aim 2, we will evaluate POWV lethality, viral loads, and infiltrating leukocytes in the CNS of F2 mice and map QTL associated with these phenotypes to identify host genetic elements that contribute to POWV susceptibility. The proposed studies will further our understanding of flavivirus neuroinvasive disease through identification of host genetic factors that modulate POWV susceptibility in mice and provide insights into factors that impact neuroinvasive flaviviruses more broadly. The proposed training plan will focus on building a foundation in quantitative genetics techniques to investigate viral and immunologic mechanisms of POWV pathogenesis, and will prepare me for a career as an independent investigator using quantitative genetics techniques to study infectious diseases.