Reverse genetics to develop a second generation Rift Valley fever vaccine

逆向遗传学开发第二代裂谷热疫苗

• 批准号: 8206484
• 负责人: Tetsuro Ikegami
• 金额: $ 38.25万
• 依托单位: UNIVERSITY OF TEXAS MED BR GALVESTON
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-12-15 至 2015-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8206484
• 关键词: African; Air; Amino Acid Substitution; Attenuated; Attenuated Live Virus Vaccine; Bioterrorism; Bunyaviridae; Categories; Cells; Chemicals; Communicable Diseases; Communities; Country; Culicidae; Cytoplasmic Tail; Data; Diploidy; Disease; Encephalitis; Family; Generations; Genetic; Genetic Transcription; Genome; Genus Phlebovirus; Glycoproteins; Goals; Human; Life; Livestock; Mutagens; Mutation; Names; National Institute of Allergy and Infectious Disease; Nonstructural Protein; Orthobunyavirus; Phenotype; Proteins; RNA; RNA Viruses; Recombinants; Research Project Grants; Resource Sharing; Retinal Vasculitis; Rift Valley Fever; Rift Valley fever virus; Risk; Ruminants; Safety; Serial Passage; Structural Protein; System; Training; Vaccination; Vaccines; Variant; Viral; Viral Hemorrhagic Fevers; Viral Nonstructural Proteins; Virion; Virulence; Virulent; Virus; Workplace; attenuation; biocontainment facility; climate change; genetic vaccine; immunogenic; immunogenicity; improved; in utero; mouse model; mutant; next generation; offspring; pathogen; plasmid DNA; positional cloning; preclinical safety; programs; public health relevance; vaccine candidate; vaccine development; working group

DESCRIPTION (provided by applicant): Rift Valley fever virus (RVFV), which belongs to the genus Phlebovirus, family Bunyaviridae, is one of the most important emerging viruses. It is listed as an NIAID category A pathogen. RVFV is transmitted by mosquitoes and causes severe disease in both humans and livestock. A proportion of infected humans develop hemorrhagic fever, encephalitis or retinal vasculitis; the offspring of infected ruminants often die in utero. RVFV is endemic in sub-Saharan African countries, but other countries are preparing for potential introductions of RVFV due to climate change, air transport, and/or bioterrorism. The only truly effective countermeasure is vaccination. RVFV has a tripartite negative-stranded RNA genome composed of the S-, M- and L-segments. The genome encodes 4 major structural proteins (N, Gn, Gc and L), 2 nonstructural proteins (NSs and NSm) and a 78-kD protein whose function is poorly characterized. A candidate live-attenuated vaccine, MP-12, was developed by 12 serial passages of the wild-type ZH548 strain in human diploid MRC-5 cells in the presence of a chemical mutagen. Our preliminary data in the mouse model suggest that MP-12 is attenuated by the combined effect of partially attenuated M- and L-segments. The current MP-12 vaccine poses a significant risk for use in humans because attenuation of the virus is not complete, and reversion of either the M- or L- segment could potentially increase the virulence of MP-12. Therefore, it is essential to characterize the mechanism of MP-12 attenuation to further improve its safety. My long term goal is to establish effective countermeasures against highly virulent negative-stranded RNA viruses, with special emphasis on vaccination. The central hypothesis is that the current candidate MP-12 vaccine can be further improved for safety by introducing mutations into either the S- or M-segment by reverse genetics while retaining immunogenicity. The overall objective is to characterize existing attenuation mutations in the MP-12 genome, and improve the safety of MP-12 by incorporating further attenuation mutations into the S- or M-segment. The three specific aims are proposed as follows: Specific Aim 1: To identify and characterize attenuation mutations of MP-12, Specific Aim 2: To attenuate the MP-12 S-segment without reducing the immunogenicity of MP-12, and Specific Aim 3: To attenuate the MP-12 M-segment by modifying the cytoplasmic domains of Gn or Gc. The proposed study will harness the advantage of using of reverse genetics for vaccine development, and develop a next generation of live-attenuated RVFV vaccine candidates that are highly immunogenic and very safe. PUBLIC HEALTH RELEVANCE: Rift Valley fever virus MP-12 strain, a live-attenuated vaccine candidate, has a potential risk to increase the virulence by a few mutations. We will identify and characterize the attenuation mutations of existing MP-12 vaccine and generate further attenuated but immunogenic second generation MP-12 vaccines.

描述（申请人提供）： 裂谷热病毒（RVFV）属于布尼亚病毒科白蛉病毒属，是最重要的新兴病毒之一。它被列为 NIAID A 类病原体。 RVFV 通过蚊子传播，会导致人类和牲畜严重疾病。部分感染者会出现出血热、脑炎或视网膜血管炎；受感染的反刍动物的后代常常在子宫内死亡。裂谷热病毒在撒哈拉以南非洲国家流行，但由于气候变化、航空运输和/或生物恐怖主义，其他国家正在为可能引入裂谷热病毒做好准备。唯一真正有效的对策是接种疫苗。 RVFV 具有由 S、M 和 L 片段组成的三部分负链 RNA 基因组。该基因组编码 4 种主要结构蛋白（N、Gn、Gc 和 L）、2 种非结构蛋白（NSs 和 NSm）和一种 78 kD 的蛋白，其功能尚不清楚。候选减毒活疫苗 MP-12 是通过在化学诱变剂存在下将野生型 ZH548 菌株在人二倍体 MRC-5 细胞中连续传代 12 次而开发的。我们在小鼠模型中的初步数据表明，MP-12 通过部分减弱的 M 和 L 片段的综合作用而减弱。目前的 MP-12 疫苗在人类中使用存在重大风险，因为病毒的减毒不完全，并且 M 或 L 片段的逆转可能会增加 MP-12 的毒力。因此，有必要表征MP-12的衰减机制以进一步提高其安全性。 我的长期目标是针对高毒力负链RNA病毒建立有效的对策，特别强调疫苗接种。中心假设是，通过反向遗传学在 S 或 M 片段中引入突变，同时保留免疫原性，可以进一步提高当前候选 MP-12 疫苗的安全性。总体目标是表征 MP-12 基因组中现有的减毒突变，并通过将进一步的减毒突变纳入 S 或 M 片段来提高 MP-12 的安全性。提出的三个具体目标如下：具体目标 1：鉴定和表征 MP-12 的减毒突变，具体目标 2：在不降低 MP-12 免疫原性的情况下减弱 MP-12 S 区段，具体目标 3：通过修饰 Gn 或 Gc 的胞质结构域来减弱 MP-12 M 区段。拟议的研究将利用反向遗传学在疫苗开发中的优势，开发具有高免疫原性且非常安全的下一代RVFV减毒活疫苗候选物。 公共卫生相关性：裂谷热病毒 MP-12 株是一种减毒活疫苗候选株，存在通过一些突变增加毒力的潜在风险。我们将鉴定和表征现有 MP-12 疫苗的减毒突变，并产生进一步减毒但具有免疫原性的第二代 MP-12 疫苗。