The yellow fever vaccine saga: Defining the viral and host determinants responsible for success versus failure

 描述(由申请人提供)：减毒黄热病病毒活疫苗17D是由强毒Asibi株体外连续传代开发的，是最成功的疫苗之一，基本上提供了对感染野生型黄热病病毒引起的疾病的终生保护。虽然疫苗株对内脏和神经的嗜性明显低于强毒株，但尽管成功使用17D疫苗超过70年，并了解两种病毒株的序列，但其减毒机制仍完全不清楚。使用非肥胖糖尿病小鼠(携带Rag1和IL2rγ零突变的非肥胖型糖尿病小鼠)进行的新的初步研究表明，感染ASIBI可以导致100%的致死率，而17D感染是非致命性的。此外，ASIBI感染原代胎肝细胞或iHEPs会导致持续复制，而17D则被清除。我们推测，Asibi毒力与对抗(或不诱导)抗YFV天然免疫的能力有关，这种天然免疫在17D时丢失，导致其减弱。此外，我们假设，在其他健康的人遭受严重的疫苗不良反应时，天然免疫途径(S)的组成部分存在基因突变，该基因通常控制17D，但可被ASIBI和其他强毒株抵消。利用分子病毒学和基因组学方法，在基于细胞和小动物模型的系统中，以及对人类样本的研究，本项目将1)确定ASIBI和17D在与宿主天然免疫途径相互作用方面的差异，2)绘制17D衰减的遗传决定因素图，以及3)表征与17D疫苗接种的严重不良事件相关的宿主遗传决定因素。这项工作将提供有关YFV 17D疫苗的反应、疫苗减毒机制的信息，并可能揭示新的先天免疫拮抗机制。对易发生不良事件的遗传缺陷的了解将使疫苗前测试能够识别高危个体。总而言之，世界卫生组织将支持开发安全有效的YFV和其他黄病毒疫苗。

 DESCRIPTION (provided by applicant): The live-attenuated yellow fever virus (YFV) vaccine 17D, developed by serial passaging in vitro of the virulent Asibi strain, is one of the most successful vaccines, providing an essentially life-long protection from disease caused by infection with wildtype YFV. While the vaccine strain is markedly less viscerotropic and neurotropic than virulent strains, the mechanism of attenuation remains completely unknown despite more than 70 years of successful 17D vaccine use and knowledge of the sequences of both virus strains. New preliminary studies using NRG mice (non-obese diabetic mice harboring the Rag1null and IL2rγnull mutations), which lack B, T and NK cells, but retain a functional innate immune system, demonstrate that infection with Asibi results in 100% lethality, while 17D infection is non-lethal. Moreover, infection of primary fetal hepatocytes or iHEPs with Asibi results in persistent replication, while 17D is cleared. We hypothesize that Asibi virulence is related to the ability to counteract (or not induce) anti-YFV innate immunity, which is lost in 17D leading to its attenuation. Moreover, we posit that otherwise healthy individuals suffering from severe vaccine adverse reactions harbor genetic mutations in components of innate immune pathway(s) that normally control 17D, but are counteracted by Asibi and other virulent strains. Using molecular virologic and genomic approaches in cell-based and small animal model-based systems, as well studies on human samples, this project will 1) identify the differences between Asibi and 17D in their interaction with host innate immune pathways, 2) map the genetic determinants responsible for 17D attenuation, and 3) characterize the host genetic determinants associated with serious adverse events to 17D vaccination. The work will provide information on responses to the YFV 17D vaccine, the mechanism of vaccine attenuation, and may uncover novel innate immune antagonism mechanisms. Knowledge of genetic defects predisposing to adverse events will allow pre-vaccine testing to identify at-risk individuals. All together the wor will support the development of safe and effective vaccines for YFV and other flaviviruses.