Engineering high fidelity mutations to increase safety of live-attenuated alphavirus vaccines

项目摘要 减毒活疫苗是预防病毒性疾病的金标准，但它们可以 恢复毒性，有时会导致严重或致命的疾病。蚊子传播的 基孔肯雅病毒（CHIKV）和委内瑞拉马脑炎（VEEV）是 分别产生使人衰弱的关节炎综合征或脑炎的RNA病毒。 这两种病毒都反复出现，在全世界造成数百万人感染， 自2013年以来，CHIKV已扩展到美洲，这表明对 疫苗。尽管已经开发了减毒活候选人疫苗用于 对于这两种病毒，目前还没有获得许可的疫苗，部分原因是 回复突变引起的临床试验因此，有必要增加 遗传稳定性的减毒活病毒候选疫苗，以提高安全性。目标 该项目的目的是开发安全有效的CHIKV和VEEV疫苗， 每年在全球范围内预防数百万人感染。变异的病毒变种 频率较低会产生较少的突变，赋予毒力，因此可能 作为更安全的减毒活疫苗候选物。这个项目将使用高保真 我们已经鉴定并表征了插入候选CHIKV的变体， VEEV疫苗需要了解：1）稳定性、感染性和逆转的可能性; 2） 高保真突变的掺入是否提高了疫苗的安全性， 在建立的小鼠模型中维持或增加免疫原性;和3） 衰减机制。这种方法代表了保真度的第一次使用 调节以增加活甲病毒疫苗候选物的安全性。如果成功，这 战略将有可能导致更广泛的应用保真度的变种，以改善 可用于其他减毒活甲病毒疫苗平台的疫苗安全性 可能还有其他RNA病毒。

Project Summary Live-attenuated vaccines are the gold standard for preventing viral illness but they can revert to virulence, sometimes causing severe or fatal disease. The mosquito-borne alphaviruses chikungunya (CHIKV) and Venezuelan equine encephalitis (VEEV) are RNA viruses that produce a debilitating arthritic syndrome or encephalitis, respectively. Both have repeatedly emerged to produce millions of human cases worldwide and CHIKV has expanded into the Americas since 2013, indicating increasing need for vaccines. Although live-attenuated candidate human vaccines have been developed for both viruses, no licensed vaccines currently exist, in part due to adverse events in clinical trials caused by revertant mutations. There is therefore a need to increase the genetic stability of live-attenuated virus vaccine candidates to improve safety. The goal of this project is to develop safe and effective CHIKV and VEEV vaccines to prevent millions of human infections globally each year. Virus variants that mutate less frequently would accrue fewer mutations that confer virulence, and may therefore serve as safer live-attenuated vaccine candidates. This project will use high fidelity variants we already identified and characterized inserted into candidate CHIKV and VEEV vaccines to understand: 1) stability, infectivity, and potential for reversion; 2) whether incorporation of high fidelity mutations improves vaccine safety while maintaining or increasing immunogenicity in established mouse models; and 3) mechanism(s) of attenuation. This approach represents the first use of fidelity modulation to increase safety of live alphavirus vaccine candidates. If successful, this strategy will potentially lead to a broader application of fidelity variants in improving vaccine safety that can be used for other live-attenuated alphavirus vaccine platforms and possibly other RNA viruses.