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-蚊循环，导致数百万例高度衰弱的慢性关节炎病例。数十起经由病毒携带者输入的CHIKV病例强调了CHIKV对西半球的风险。基孔肯雅热可能是致命的，目前尚无有效的治疗方法，因此需要一种有效的疫苗。为了在第三世界的流行地区使用，一种理想的疫苗必须制造成本低廉，并在单次注射后诱导快速、长期的免疫。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发生病毒血症时不能感染蚊子载体。为了实现这些目标，我们开发了新的、创新的方法来稳定甲型病毒的衰减，既保留免疫原性，又消除蚊子感染的可能性。利用在昆虫细胞中功能较差的小核糖核酸内核糖体进入位点（IRES），结合导致结构蛋白过度表达的甲病毒亚基因组启动子的失活，我们生产了一种CHIKV活疫苗株，它结合了减毒活疫苗的优点，但它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，不能在蚊子细胞中复制。在这个项目中，我们将进一步开发这种CHIK候选疫苗，为新药申请和一期人体研究做准备，具体目标如下：通过分析体外RNA复制、蛋白表达和翻译效率水平以及体内复制和传播模式，确定疫苗衰减的机制。2. 确定保护性免疫的相关因素，确定控制疫苗复制所需的先天和适应性免疫反应的组成部分。3. 优化在Vero细胞中生产的候选疫苗。4. 开发和鉴定GMP主病毒种子和工作病毒种子库。5. 开展质量控制和放行试验，生产临床前GMP批次疫苗。6. 在非临床GLP研究中测试疫苗的安全性。7. 提交IND和生产用于1期临床试验的疫苗批次。这种学术和工业伙伴之间合作的创新产品将对亚洲和非洲产生巨大影响，在这些地区，CHIKV造成严重的健康影响和经济困难，并将大大减少CHIKV在西半球输入和建立的风险。此外，对其衰减机制的改进理解和基于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/或未来有可能出现的其他阿尔法病毒。

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.