Development of recombinant VSV vaccines for emerging bunyaviruses

项目总结/摘要 新出现的病毒感染仍然是对人类健康的全球威胁。布尼亚病毒是RNA的最大目 病毒，包括许多临床相关的人类病原体，如拉沙，裂谷热和各种 引起病毒性出血热（VHF）的汉他病毒。SFTSV或重度发热伴血小板减少症 综合症病毒，是一种新兴的蜱传布尼亚病毒，已在东亚（中国，日本， 韩国、越南），病死率高达30%。宿主蜱虫载体现已在一个大的 在许多野生和家养动物物种中发现了SFTSV， 人畜共患病传染给人类的风险。虽然人类通常是死胡同的主机，人与人之间 已证实通过血液和粘膜分泌物传播。此外，SFTSV还拥有 分段的基因组，增加基因重组和突变的能力。由于这些特点，在其2017年 世界卫生组织在《研究和发展蓝图》中将SFTSV确定为11种可能导致 在未来爆发。正如我们从最近人畜共患病暴发的经验中所了解到的那样， 是最重要的我们建议继续开发重组水泡性口炎 病毒（rVSV）为基础的疫苗SFTSV。rVSV是一种获批的免疫原性强效疫苗平台 并被证明是可以容忍的我们小组的初步工作表明，rVSV-SFTSV可以引起保护作用， 在小鼠中，在免疫功能低下的动物中和在CNS注射后是可耐受的，并且可以产生交叉保护 一种相关的布尼亚病毒的反应。此外，我们观察到SFTSV特异性T细胞和抗体水平升高， 针对SFTSV刺突蛋白Gn和Gc的应答。在第一阶段，我们建议改善 我们的载体将增加病毒滴度以促进疫苗制造并增加免疫原性， 动物在目标1中，我们将专注于将改进SFTSV Gn/Gc的反向工程突变到rVSV中， 掺入到颗粒中，从而改善病毒复制和体外产量。我们将描述这些第二 使用基于分子和细胞的测定法对病毒复制、GnGc表达进行评分， 以及GnGc掺入VSV病毒体。在目标2中，我们将评估我们的Gen 2疫苗 在致死性SFTSV攻击研究中保护动物。我们假设GnGc表达增加， Gen 2载体的复制将导致接种疫苗的动物中的免疫应答改善， Gen 1载体。我们将评估免疫相关的保护，如增强中和和交叉保护 与Gen 1 rVSV-SFTSV疫苗接种的动物相比，如果成功， 我们的第一阶段将为第二阶段奠定基础，以推进制造业和严格研究保护性技术。 我们的疫苗在更先进的动物模型中的能力。

PROJECT SUMMARY/ABSTRACT Emerging viral infections remain a global threat to human health. Bunyaviruses are the largest order of RNA viruses that includes many clinically relevant human pathogens such as Lassa, Rift Valley Fever and various hantaviruses which cause viral hemorrhagic fever (VHF). SFTSV, or Severe fever with thrombocytopenia syndrome virus, is an emerging tick-borne bunyavirus that has caused outbreaks in Eastern Asia (China, Japan, Korea, Vietnam) with up to a 30% case fatality rate. The host tick vector has now been discovered over a large geographical setting and SFTSV has been found in numerous wild and domestic animal species highlighting a risk for zoonotic spillover into humans. Though humans are usually dead-end hosts, human to human transmission has been documented through blood and mucosal secretions. Furthermore, SFTSV has a segmented genome which increases ability to reassort genes and mutate. Due to these features, in its 2017 “Research and Development Blueprint” the WHO identified SFTSV as one of 11 pathogens likely to cause a sever outbreak in the future. As we have learned, from experience with recent zoonotic outbreaks, preparedness is of the utmost importance. We are proposing to continue development of a recombinant vesicular stomatitis virus (rVSV)-based vaccine for SFTSV. rVSV is an approved vaccination platform that is immunogenically potent and proven tolerable. Preliminary work from our group has demonstrated that rVSV-SFTSV can elicit protection in mice, is tolerable in immunocompromised animals and upon CNS injection, and can generate cross protecting responses to a related bunyavirus. Furthermore, we observe elevated SFTSV-specific T cell and antibody responses against both SFTSV spike proteins, Gn and Gc. In this Phase I, we propose to improve the design of our vector which will increase viral titers to facilitate vaccine manufacturing and increase immunogenicity in animals. In aim 1, we will focus on reverse engineering mutations into rVSV that will improve SFTSV Gn/Gc incorporation into particles thereby improving virus replication and yield in vitro. We will characterize these 2nd generation (Gen2) vaccines using molecular and cell-based assays scoring for viral replication, GnGc expression in infected cells and incorporation of GnGc in VSV virions. In aim 2, we will assess the ability of our Gen2 vaccine to protect animals in lethal SFTSV challenge studies. We hypothesize that increased GnGc expression and replication of the Gen2 vectors will lead to improved immune responses in vaccinated animals compared to the Gen1 vector. We will assess immune correlates of protection such enhanced neutralizing and cross protective antibodies as well as robust T cell responses compared to Gen1 rVSV-SFTSV vaccinated animals. If successful, our Phase I would set the foundation for a Phase II to advance manufacturing and stringently study protective capacity of our vaccine in more advanced animal models.