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疾病的黄金标准，但它们可以 回复到毒性，有时会导致严重或致命的疾病。蚊子传播的 甲型病毒基孔肯雅(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症或脑炎的RNA病毒。 两者都反复出现，在全球范围内产生了数百万人感染病例， 自2013年以来，CHIKV已扩展到美洲，表明对 疫苗。尽管已经开发出减毒的候选人类疫苗 这两种病毒目前都没有获得许可的疫苗，部分原因是 由突变引起的临床试验。因此，有必要增加 候选减毒活病毒疫苗的遗传稳定性提高安全性。目标是 该项目的主要目的是开发安全有效的CHIKV和VEEV疫苗，以 每年在全球范围内预防数百万人感染。变异的病毒变种 更少的频率会产生更少的赋予毒力的突变，因此 作为更安全的减毒活疫苗候选疫苗。该项目将使用高保真 我们已经确定和表征的变异插入到候选CHIKV和 Veev疫苗要了解：1)稳定性、传染性和逆转的可能性；2) 高保真突变的加入是否提高了疫苗的安全性 在已建立的小鼠模型中保持或增加免疫原性；以及3) 衰减机理(S)。这种方法代表了保真度的首次使用 调制以增加甲型病毒活疫苗候选疫苗的安全性。如果成功，这将是 策略将潜在地导致保真度变量在提高 可用于其他甲型减毒活疫苗平台的疫苗安全性 可能还有其他的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.