An Informed Approach to Live Attenuated Vaccines against Encephalitis Alphaviruses

摘要 东方（EEEV）、委内瑞拉（VEEV）和西方（WEEV）马脑炎病毒 是蚊子传播的甲病毒，有可能导致致命的神经侵入性疾病， 人类和家养动物的疾病。这些病毒也可以通过 气溶胶途径，因此具有作为生物战/生物恐怖主义制剂的巨大潜力。在 2019年，EEEV人类感染增加到自20世纪50年代以来未见的水平。目前， 目前还没有针对这些甲病毒的抗病毒疗法或疫苗。现有 研究性VEEV减毒活疫苗（LAV; TC-83）的生产时间超过40年 前，是高度反应原性，免疫原性差，并导致高达20%的疾病， 受惠人士对于EEEV和WEEV，研究用福尔马林灭活疫苗 给处于危险中的工人。虽然两者都能引起抗体反应，但它们提供了 不确定的保护，需要多次加强注射。三价兽用疫苗 抗VEEV、EEEV和WEEV的疫苗是可用的，但其免疫原性很差， 动物必须每年加强免疫，在接种疫苗的动物中发现疾病。这里我们 建议开发针对这些甲病毒的安全有效的LAV疫苗， 最近的进展，了解每一个毒力机制。这些 这些进展将允许特异性降低致病性结构域的诱变 毒力，增加细胞因子诱导和抗原呈递，并提供持久的 保护此外，每个突变的作用机制将是已知的， 每一个都将被特别设计成抵抗反转。我们将联合收割机的突变， 为每种病毒创建最佳疫苗株，然后研究它们在 多价制剂，对兽医疫苗开发至关重要， 人类制剂。我们将确定每种疫苗的保护相关性， 解决对脑炎病毒的交叉保护程度。首次与 甲病毒，具有已知机制的突变的单独和组合效应 将测试对病毒复制、疾病和免疫原性的影响， 动物

ABSTRACT Eastern (EEEV), Venezuelan (VEEV), and Western (WEEV) equine encephalitis viruses are mosquito-transmitted alphaviruses with the potential to cause fatal neuroinvasive disease in humans and domesticated animals. These viruses also can be spread by the aerosol route and thus, have significant potential as biowarfare/bioterrorism agents. In 2019, EEEV human infections increased to levels not seen since the 1950s. Currently, there are no antiviral therapies or vaccines licensed for these alphaviruses. The existing investigational live-attenuated VEEV vaccine (LAV; TC-83) was generated >40 years ago, is highly reactogenic, poorly immunogenic, and causes disease in up to 20% of recipients. For EEEV and WEEV, investigational formalin-inactivated vaccines have been given to at-risk workers. While both elicit antibody responses, they provide uncertain protection and require multiple booster injections. A trivalent veterinary vaccine against VEEV, EEEV and WEEV is available but is so poorly immunogenic that domestic animals must be boosted annually and disease is seen in vaccinated animals. Here, we propose to develop safe and effective LAVs vaccine against these alphaviruses using recent advances in understanding of the virulence mechanisms of each. These advances will allow mutagenesis of pathogenicity domains that specifically reduce virulence, increase cytokine induction and antigen presentation and provide long-lasting protection. Furthermore, the mechanism of action of each mutation will be known and each will be specifically designed to resist reversion. We will combine mutations to create an optimal vaccine strain for each virus and then investigate their use in multivalent formulations, critical to veterinary vaccine development and highly desired for human formulations. We will identify correlates of protection for each vaccine and address the extent of cross-protection versus encephalitic viruses. For the first time with alphaviruses, the individual and combined effects of mutations with known mechanisms of action will be tested for effects on virus replication, disease and immunogenicity in animals.