Toward Control of Rift Valley Fever Virus Replication

裂谷热病毒（RVFV）属于NIAID A类名单病原体和CDC名单病原体。 潜在的生物恐怖分子RVFV属于布尼亚病毒科中的白蛉病毒属，是一种大的， 包含三个RNA基因组片段的广泛多样的包膜RNA病毒组。裂谷热是 一种撒哈拉以南非洲地区的地方病，在爆发性蚊媒流行中出现 造成牛羊群的巨大经济损失，还引起出血热， 人类脑炎、视网膜血管炎和轻微疾病。RVFV已出口到埃及， 阿拉伯半岛，那里有进一步蔓延的危险。RVFV在北美的引入将引起恐慌 一般人口和牲畜的影响可能是经济上的毁灭性的。在新大陆 地点RVFV可能会维持非洲常见的感染宿主，而 同时潜在地在新的野生动物宿主中建立新的放大器，从而导致更高的 RVFV感染的人的病毒血症水平;这种流行病将与人类的可能性成熟 用作放大器。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群的RVFV疫苗并不存在。 两种RVFV减毒活毒株MP-12和克隆13具有作为疫苗候选物的潜力。这个礼物 该申请旨在使用RVFV开发新的基于MP-12的活RVFV人候选疫苗， 反向遗传学系统，这是我们小组最近开发的。有相当多的证据表明 体液免疫对于抵抗RVFV是必要的和充分的，并且RVFV被认为是 血清单型的我们假设，安全的、非致病性的MP-12衍生病毒引起强的 体液免疫应答，特别是针对两种包膜蛋白Gn和Gc的体液免疫应答，对于晚期胰腺癌是理想的。 RVFV疫苗研究。在本申请中，我们将通过以下方式产生先进的MP-12衍生候选疫苗： 在L和M片段RNA中引入突变。为此，我们将首先检查 在野生型RVFV和MP-12之间的抵抗病毒，并测试感染后的体液免疫应答。 这些病毒感染了小鼠。选定的免疫病毒将进一步修改，以提高免疫力 使用小鼠模型系统的功效。我们最近的研究表明， Gn基因对野生型RVFV的毒力有显著影响。我们将研究单个核苷酸 替换可影响野生型RVFV毒力。我们希望从拟议的研究中获得的数据 这将是人类RVFV活疫苗的突破性进展，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.