Development of a Replicon RNA-based Vaccine against Dengue and Zika

摘要 该项目的长期目标是开发一种登革热寨卡疫苗， 登革热（DENV 1 -4）和寨卡（ZIKV）病毒的四种血清型，具有最大的安全性和有效性。到 迄今为止，黄病毒疫苗的开发集中在中和抗体（nAb）的诱导上， 它们被认为是防止自然感染的关键机制。然而，在这方面， 登革病毒和ZIKV可能是不寻常的，因为对疫苗接种或先前感染的弱抗体应答可以 诱导感染和发病过程中抗体依赖性增强（ADE） 再次感染事实上，已经在儿童中记录了具有严重后遗症的DENV疾病， 目前只有DENV疫苗获得许可。因此，本申请的主要目的是开发一种 不能介导ADE的针对DENV和ZIKV的有效疫苗。我们假设这种疫苗 将需要引发强烈的nAb反应和强烈的T细胞效应器反应， 任何ADE介导的抗体的存在，基于我们的工作，调查抗体之间的相互作用， 对DENV和ZIKV的T细胞应答。特别是，我们已经表明，CD 8 T细胞介导的交叉- 针对异型DENV和ZIKV感染的保护，以及DENV疫苗引发的CD 8 T细胞 可以预防ADE。此外，我们的初步数据显示，表达 ZIKV非结构蛋白3仅激发T细胞而非nAb应答并赋予针对ZIKV的保护 小鼠的挑战因此，我们假设我们的表达Ab-1和Ab-2两者的组合DENV-ZIKV疫苗是有效的。 DENV 1 -4和ZIKV的T细胞靶向蛋白将产生体液和细胞免疫应答 提供针对所有五种病毒的强大长期保护。我们将通过实现以下目标来验证这一假设： 1）评估DENV-ZIKV疫苗的免疫原性和功效。2)到 确定DENV-ZIKV疫苗诱导的保护性免疫应答的持久性和机制基础。 免疫力

ABSTRACT The long-term goal of this project is to develop a dengue-Zika vaccine that provides protection against the four serotypes of dengue (DENV1-4) and Zika (ZIKV) viruses with maximal safety and efficacy. To date, flavivirus vaccine development has focused on the induction of neutralizing antibodies (nAbs), as they have been assumed to be the key mechanism for protection against natural infection. However, DENV and perhaps ZIKV are unusual in that weak Ab responses to vaccination or prior infection can induce antibody-dependent enhancement (ADE) of infection and pathogenesis during subsequent reinfections. In fact, DENV disease with severe sequalae has been documented in children given the only currently licensed DENV vaccine. Thus, the primary objective of this application is to develop an effective vaccine against DENV and ZIKV that cannot mediate ADE. We hypothesize that this vaccine will need to elicit both strong nAb responses and strong T cell effector responses that will counterbalance the presence of any ADE-mediating Abs, based on our work investigating the interplay between Ab and T cell responses to DENV and ZIKV. In particular, we have shown that CD8 T cells mediate cross- protection against heterotypic DENV and ZIKV infections, and that DENV vaccine-elicited CD8 T cells can prevent ADE. In addition, our preliminary data show that an RNA replicon-based vaccine expressing ZIKV nonstructural protein 3 elicits only T cell but not nAb responses and confers protection against ZIKV challenge in mice. Thus, we hypothesize that our combinatorial DENV-ZIKV vaccine expressing both Ab- and T cell-targeting proteins of DENV1-4 and ZIKV will produce humoral and cellular immune responses that provide robust, long-term protection against all five viruses. We will test this hypothesis by achieving the following Specific Aims: 1) To evaluate immunogenicity and efficacy of a DENV-ZIKV vaccine. 2) To determine the durability and mechanistic underpinnings of DENV-ZIKV vaccine-induced protective immunity.