Novel Vaccine Technology for Chikungunya

描述（由申请人提供）：基孔肯雅病毒（CHIKV）最近从非洲出现，进入城市人-蚊子循环，导致数百万例高度衰弱的慢性关节痛疾病。通过病毒血症旅行者输入的数十例CHIKV强调了CHIKV对西半球的风险。基孔肯雅热（CHIK）没有有效的治疗方法，这可能是致命的，因此需要有效的疫苗。为了在第三世界流行地区使用，理想的疫苗必须制造成本低廉，并在单次剂量后诱导快速、长期的免疫力。为了在非流行地区安全使用，疫苗还必须在宿主防御受损的疫苗接种者中发生病毒血症的情况下不能感染蚊媒。为了实现这些目标，我们开发了新的创新方法来稳定甲病毒减毒，保留免疫原性，同时消除蚊子感染的可能性。使用在昆虫细胞中功能较差的小核糖核酸病毒内部核糖体进入位点（IRES），结合驱动结构蛋白过表达的甲病毒亚基因组启动子的失活，我们产生了活CHIKV疫苗株，其结合了活减毒疫苗的经证实的优点，但其应该比传统方法更稳定地减毒。这种CHIKV疫苗在小鼠模型中高度减毒但具有免疫原性，并且不能在蚊子细胞中复制。在本项目中，我们将进一步开发这种CHIK候选疫苗，为研究性新药申请和1期人体研究做准备，具体目标如下：1.通过分析RNA复制水平、蛋白质表达和体外翻译效率以及体内复制和传播模式，确定疫苗减毒的机制。2.定义保护性免疫的相关性，并确定控制疫苗复制所需的先天性和适应性免疫反应的组成部分。3.优化候选疫苗以在Vero细胞中生产。4.开发和表征GMP主病毒种子和工作病毒种子储备液。5.开展质量控制和放行检测，并生产临床前GMP批次的疫苗。6.在非临床GLP研究中测试疫苗的安全性。7. IND提交和生产用于1期临床试验的疫苗批次。学术界和工业界合作伙伴之间的这种合作的创新产品将在亚洲和非洲产生巨大的影响，在那里CHIK造成严重的健康影响和经济困难，并将大大降低CHIKV输入和建立在西半球的风险。此外，对其减毒机制的更好理解以及我们基于IRES的疫苗平台技术的进一步发展，将使我们能够快速生成可预测的安全有效的疫苗，以对抗代表生物防御威胁和/或未来可能出现的其他甲病毒。

DESCRIPTION (provided by applicant): Chikungunya virus (CHIKV) recently emerged from Africa into an urban human-mosquito cycle to cause millions of cases of highly debilitating, often chronic arthralgic disease. Dozens of CHIKV importations via viremic travelers underscore the risk of CHIKV to the Western hemisphere. There is no effective treatment for chikungunya fever (CHIK), which can be fatal, so an effective vaccine is needed. For use in third world, endemic locations, an ideal vaccine must be inexpensive to manufacture and induce rapid, long-lived immunity after a single dose. To be used safely in nonendemic locations, the vaccine must also be incapable of infecting mosquito vectors in the event that viremia occurs in a vaccinee with impaired host defense. To achieve these goals, we developed novel, innovative approaches to stable alphavirus attenuation that retain immunogenicity yet eliminate the possibility of mosquito infection. Using a picornavirus internal ribosome entry site (IRES) that functions poorly in insect cells, combined with inactivation of the alphavirus subgenomic promoter that drives overexpression of the structural proteins, we produced a live CHIKV vaccine strain that combines the proven advantages of live-attenuated vaccines, yet which should be more stably attenuated than traditional approaches. This CHIKV vaccine is highly attenuated yet immunogenic in mouse models, and is incapable of replicating in mosquito cells. In this project, we will further develop this CHIK vaccine candidate in preparation for an investigational new drug application and Phase 1 human studies, using the following specific aims: 1. Determine the mechanism of vaccine attenuation by analyzing levels of RNA replication, protein expression and translational efficiency in vitro and patterns of replication and spread in vivo. 2. Define correlates of protective immunity and determine components of the innate and adaptive immune response required to control vaccine replication. 3. Optimize the vaccine candidate for production in Vero cells. 4. Develop and characterize GMP master virus seed and working virus seed stocks. 5. Develop quality control and release tests and manufacture a preclinical GMP lot of the vaccine. 6. Test the vaccine in nonclinical GLP studies for safety. 7. IND submission and manufacture of vaccine lots for Phase 1 clinical testing. The innovative product of this collaboration between academic and industrial partners will have dramatic impacts in Asia and Africa where CHIK causes both severe health effects and economic hardship, and will greatly reduce the risk of CHIKV importation and establishment in the Western Hemisphere. In addition, the improved mechanistic understanding of its attenuation and further development of our IRES-based vaccine platform technology will allow us to rapidly generate predictably safe and effective vaccines against other alphaviruses that represent biodefense threats and/or that have the potential that emerge in the future.