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: 8389649
• 负责人: Tetsuro Ikegami
• 金额: $ 35.96万
• 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/8389649
• 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.

描述（由申请人提供）：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由蚊子传播，并在人类和牲畜中引起严重疾病。一部分受感染的人会发展为出血热、脑炎或视网膜血管炎;受感染的反刍动物的后代通常在子宫内死亡。RVFV在撒哈拉以南非洲国家流行，但其他国家正在准备由于气候变化，航空运输和/或生物恐怖主义而引入RVFV。唯一有效的预防措施是接种疫苗。 RVFV具有由S-、M-和L-区段组成的三重负链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（NS和NSm）和一种78 kD的蛋白，该蛋白的功能尚不清楚。通过在存在化学诱变剂的情况下将野生型ZH 548株在人二倍体MRC-5细胞中连续传代12次，开发了候选减毒活疫苗MP-12。我们在小鼠模型中的初步数据表明，MP-12通过部分减毒的M-和L-节段的联合作用而减毒。目前的MP-12疫苗在人类中使用时具有显著的风险，因为病毒的减毒不完全，M-或L-片段的回复突变可能会增加MP-12的毒力。因此，必须表征MP-12衰减的机制，以进一步提高其安全性。 我的长期目标是建立有效的对抗高毒力负链RNA病毒的对策，特别强调疫苗接种。中心假设是，通过反向遗传学将突变引入S-或M-片段，同时保留免疫原性，可以进一步改善当前候选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并入S-或M-片段中来提高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毒MP-12 S-片段，具体目标3：通过修饰Gn或Gc的胞质结构域来减毒MP-12 M-片段。这项拟议的研究将利用反向遗传学用于疫苗开发的优势，并开发下一代具有高度免疫原性和非常安全的RVFV减毒活疫苗候选物。