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（由申请人提供）：属于Bunyaviridae家族的裂谷谷热病毒（RVFV）是最重要的新兴病毒之一。它被列为病原体的NIAID类别。 RVFV是由蚊子传播的，并在人类和牲畜中引起严重疾病。一部分受感染的人会出现出血热，脑炎或视网膜血管炎；感染反刍动物的后代常常在子宫内死亡。 RVFV在撒哈拉以南非洲国家是地方性的，但是由于气候变化，航空运输和/或生物恐怖主义，其他国家正在准备潜在的RVFV介绍。唯一真正有效的对策是疫苗接种。 RVFV具有由S-，M-和L-perments组成的三方负链RNA基因组。基因组编码4种主要的结构蛋白（N，GN，GC和L），2个非结构蛋白（NSS和NSM）和一个78 kD蛋白，其功能的特征差。在化学诱变剂存在下，人类二倍体MRC-5细胞中野生型ZH548菌株的12个串行通道开发了候选疫苗MP-12。我们在小鼠模型中的初步数据表明，MP-12通过部分减弱的M-和L细分的综合作用减弱。当前的MP-12疫苗由于病毒的衰减尚不完整，因此在人类中使用了显着使用的风险，并且M-或L段的恢复可能会增加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。 我的长期目标是针对高毒性负链RNA病毒建立有效的对策，并特别强调疫苗接种。中心假设是，当前候选MP-12疫苗可以通过在保留免疫原性的同时将突变通过反向遗传学引入S-或M元素，以进一步改善安全性。总体目的是表征MP-12基因组中现有的衰减突变，并通过将进一步的衰减突变纳入S-或M段来提高MP-12的安全性。提出了三个具体目的如下：具体目的1：确定和表征MP-12的衰减突变，具体目标2：在不降低MP-12的免疫原性的情况下衰减MP-12 S段，并降低MP-12的免疫原性，并通过修改MP-12 M元素来修改细胞质量Domains或GC。拟议的研究将利用将反向遗传学用于疫苗开发的优势，并开发下一代的实时侵入的RVFV疫苗候选物，这些疫苗具有高度免疫原性且非常安全。 公共卫生相关性：裂谷发烧病毒MP-12菌株是一种活体侵蚀的疫苗，具有通过一些突变增加毒力的潜在风险。我们将确定并表征现有MP-12疫苗的衰减突变，并产生进一步的减弱但免疫原性的第二代MP-12疫苗。