Toward Control of Rift Valley Fever Virus Replication

裂谷热病毒(RVFV)属于NIAID A类病原体名单和CDC名单 潜在的生物恐怖主义特工。RVFV属于白喉病毒属，属于布尼亚病毒科，是一种大型和 包含三个RNA基因组片段的一组广泛不同的包膜RNA病毒。裂谷热是 一种撒哈拉以南非洲的地方性疾病，出现在由蚊子传播的爆炸性流行病中 造成羊群和牛群的巨大经济损失，但也引起出血热， 人类的脑炎、视网膜血管炎和较轻的疾病。RVFV已出口到埃及和 阿拉伯半岛，它有进一步蔓延的威胁。RVFV在北美的引入将引发恐慌 对一般人口和牲畜的影响可能在经济上是毁灭性的。在一个新的大陆 位置RVFV可能会保持与在非洲发现的病毒一样的感染宿主，而 同时潜在地在新的野生动物宿主中建立新的扩增器，从而导致更高的 RVFV感染者的病毒血症水平；这样的流行病可能在人类中成熟 充当扩音器。为了保护美国公民，人类疫苗对于控制 RVFV，而适用于开始大规模接种人的RVFV疫苗并不存在。 两株RVFV减毒活毒株MP-12和Clone 13有可能成为疫苗候选株。这份礼物 应用程序旨在开发基于MP-12的、使用RVFV的新的活RVFV人类疫苗候选 反向遗传学系统，这是我们课题组最近开发的。有大量证据表明 体液免疫是预防RVFV的必要条件和充分条件，RVFV被认为是 血清学上是单型的。我们假设，安全的、非致病性的MP-12衍生病毒会引发强烈的 体液免疫反应，特别是针对两种包膜蛋白Gn和GC的免疫反应，对于晚期患者来说是理想的 RVFV疫苗研究。在此应用程序中，我们将通过以下方式生成高级MP-12衍生疫苗候选 介绍L和M片段RNA的突变。为此，我们将首先检测沙门氏菌对小鼠的毒力 WT RVFV与MP-12间的重组病毒及其感染后体液免疫应答的检测 被这些病毒感染的小鼠。选定的重组病毒将被进一步修改以提高免疫力 使用鼠标模型系统的效果。我们最近的研究表明，单核苷酸替换 GN基因在很大程度上影响Wt RVFV对小鼠的毒力。我们将研究单核苷酸是如何 置换可影响wt RVFV的毒力。我们期望从拟议的研究中获得的数据 将是人类RVFV活疫苗产生的突破性进展，并将进一步加深我们对 RVFV在分子水平上的致病性。

Rift Valley fever virus (RVFV) belongs to the NIAID Category A list pathogens and the CDC list of potential bioterrorism agents. RVFV belong to the genus Phlebovirus, in the family Bunyaviridae, a large and widely diverse group of enveloped RNA viruses containing three RNA genome segments. Rift Valley fever is an endemic disease of sub-Saharan Africa that has emerged in explosive mosquito-borne epidemics resulting in massive economic loss in herds of sheep and cattle, but also causes hemorrhagic fever, encephalitis, retinal vasculitis, and lesser disease in humans. RVFV has been exported to Egypt and the Arabian peninsula, where it threatens to spread further. RVFV introduction in North America will panic the general population and the effects on livestock could be economically devastating. In a new continental location RVFV would likely maintain reservoirs of infection common to those found in Africa, while simultaneously potentially establishing new amplifiers in novel wild-animal hosts, thereby leading to higher levels of viremia in RVFV-infected humans; such an epidemic would be ripe with the possibility of humans serving as amplifiers. For the protection of American citizens a human vaccine is essential for controlling RVFV, whereas an RVFV vaccine applicable for inception of massive vaccination of people does not exist. Two live attenuated RVFV strains, MP-12 and clone 13 have potential as vaccine candidates. This present application aims to develop new MP-12-based, live RVFV human vaccine candidates using an RVFV reverse genetics system, which was recently developed by our group. There is considerable evidence that humoral immunity is necessary and sufficient for protection against RVFV and RVFV is considered to be serologically monotypic. We hypothesize that safe, nonpathogenic MP-12-derived viruses eliciting strong humoral immune responses, particularly against two envelope proteins, Gn and Gc, are ideal for advanced RVFV vaccine studies. In this application, we will generate advanced MP-12-derived vaccine candidates by introducing mutations in L and M segment RNAs. To this end, we will first examine the virulence in mice of reassortant viruses between wt RVFV and MP-12 and test for a humoral immune response after infection of the mice by these viruses. Selected reassortant viruses will be further modified to improve immunization efficacies using a mouse model system. Our recent study showed that a single nucleotide substitution in the Gn gene substantially affected the virulence of wt RVFV in mice. We will investigate how a single nucleotide substitution could affect the wt RVFV virulence. We expect that the data obtained from the proposed studies will be groundbreaking for the generation of live human RVFV vaccines and will further our understanding of RVFV pathogenicity at a molecular level.