Rational Development of a Novel Attenuated Rift Valley Fever Virus Vaccine

摘要 裂谷热病毒（RVFV）是布尼亚病毒科（Bunyaviridae）的一种典型的白蛉病毒属（Phlebovirus NIAID A类病原体清单和CDC潜在生物恐怖主义制剂清单。RVFV 导致了一种在撒哈拉以南非洲流行的疾病， 蚊子传播的流行病大量杀死了羊群和牛群， 经济损失在人类中，RVFV感染可引起出血热、脑炎和脑膜炎。 视网膜血管炎许多不同的蚊子，包括一些原产于北美， RVFV传播的有效载体。因此，RVFV引入北美 可能会在普通人群中引起恐慌，对牲畜的影响可能会导致 毁灭性的经济影响。诱导针对病毒的体液免疫应答 包膜蛋白是必要的，足以提供针对RVFV的保护。目前， 没有适用于大规模人类接种计划的RVFV疫苗。MP-12菌株， 其通过野生型RVFV株ZH 548在存在下连续传代12次获得， 5-氟尿嘧啶，在小鼠中明显减弱，但保留其免疫原性。然而，在这方面， 将MP-12腹腔接种到幼龄小鼠或SCID小鼠中产生有效病毒 在动物的中枢神经系统中复制。神经侵袭性和神经毒性 MP-12的潜力是一个值得关注的问题，当考虑到大规模接种疫苗的一般 尤其是在免疫功能低下的人群中。本申请提出了 开发具有几种突变的新型和更安全的MP-12衍生疫苗候选物 选择性地消除病毒包膜糖蛋白的特定功能， 感染细胞中中和表位的表达水平。我们将检验这一假设， 基于MP-12的候选疫苗在小鼠中表现出比MP-12更好的安全性特征，但仍然 保持其免疫原性和保护效力。在本建议中，我们将研究其遗传 在培养细胞中的稳定性，并使用 小鼠模型。

Abstract Rift Valley fever virus (RVFV), a prototypical Phlebovirus (family Bunyaviridae), belongs to the NIAID Category A list of pathogens and the CDC list of potential bioterrorism agents. RVFV causes a disease that is endemic in sub-Saharan Africa and can emerge in explosive, mosquito-borne epidemics decimating herds of sheep and cattle, resulting in enormous economic losses. In humans, RVFV infection may cause hemorrhagic fever, encephalitis, and retinal vasculitis. Many different mosquitoes, including several native to North America, are competent vectors for RVFV transmission. Thus, the introduction of RVFV into North America would likely cause panic in the general population, and the effects on livestock could have a devastating economic impact. Induction of a humoral immune response against the viral envelope proteins is necessary and sufficient to provide protection against RVFV. Currently, there is no RVFV vaccine suitable for mass human vaccination programs. The MP-12 strain, which was obtained by 12 serial passages of the wild-type RVFV strain ZH548 in the presence of 5-fluorouracil, is markedly attenuated in mice but retains its immunogenicity. However, intraperitoneal inoculation of MP-12 into young mice or SCID mice results in efficient virus replication in the animals’ central nervous system. The neuroinvasiveness and neurovirulence potential of MP-12 is a matter of concern when considering the mass vaccination of the general public, especially, in immunocompromised individuals. The present application proposes the development of a novel and safer MP-12-derived vaccine candidate having several mutations that selectively abolish specific functions of viral envelope glycoproteins and cause a higher expression level of neutralizing epitopes in infected cells. We will test the hypothesis that this MP-12-based vaccine candidate exhibits a better safety profile than MP-12 in mice but still retains its immunogenicity and protective efficacy. In this proposal, we will examine its genetic stability in cultured cells and assess its safety, immunogenicity, and protective efficacy by using mouse models.