Anti-flavivirus B cell response analysis to aid vaccine design

寨卡病毒（ZIKV）是黄病毒家族的成员，其作为引起寨卡病毒（ZIKV）的感染剂出现。 在最近的流行病期间发生的全球健康危机。ZIKV感染可导致格林-巴利综合征 在成人中，严重的胎儿神经畸形和妊娠期间胎儿死亡。ZIKV感染 主要通过蚊虫叮咬传播，而性传播和垂直传播 孕妇感染胎儿也有助于最近的流行。理想情况下，有效的ZIKV 疫苗应提供杀菌免疫，阻断最初的病毒传播， 随后感染导致的发病率。目前，没有批准的ZIKV疫苗用于疾病 预防以prM-E形式表达的膜蛋白（M）和包膜蛋白（E）是一种常见的 针对ZIKV的当前疫苗候选物的抗原选择，作为中和抗体（nAb） 可以阻止病毒进入。然而，这种新生的基于PrM-E的ZIKV疫苗可以 增加登革热病毒（DENV）的传染性，另一种黄病毒， 很大程度上与ZIKV重叠。由于E蛋白之间的高度序列同源性， ZIKV prM-E疫苗可以刺激ZIKV和DENV的抗体产生， 非中和但与DENV E蛋白交叉反应。如果随后发生登革热， 病毒感染，抗体依赖性增强（ADE）可能发生时，次优抗- ZIKV抗体与DENV病毒结合，从而增强DENV进入宿主细胞 并加剧登革热症状。预防ADE倾向抗体诱导的策略 最近已经描述了修饰的ZIKV免疫原，其不幸地显示出 对小动物的保护效果欠佳。在这里，我们专注于应用基于结构的 疫苗设计，以开发具有改善的免疫原性和降低的 DENV感染的ADE可能性。在初步研究中， 优化的佐剂在用ZIKV攻击的免疫小鼠中显示出几乎完全的保护， 并通过体外试验评估消除ADE潜力。有效的单克隆ZIKV nAb靶向 主要ZIKV E蛋白nAb决定簇，包括四级E-二聚体依赖性表位 从免疫小鼠分离的抗体证实了设计原理。在这个应用程序中，我们将扩展我们的 通过B细胞/抗体应答分析和结构分析指导的进一步免疫原设计的努力 研究ZIKV E蛋白-抗体相互作用以改进我们的主要疫苗候选物， 在实现杀菌免疫，以评估在小动物模型。如果成功，这项研究将 有助于（i）开发有效和安全的ZIKV疫苗，以及（ii）加深我们的研究。 了解对黄病毒感染和免疫的免疫反应。

Zika virus (ZIKV) is a member of flavivirus family that emerged as an infectious agent causing global health crisis during recent epidemics. ZIKV infection can cause Guillain-Barré syndrome in adults, and severe fetal neuromalformations and fetal death during pregnancy. ZIKV infection is primarily transmitted by mosquito bite, while sexual transmission and vertical transmission from infected pregnant women to fetus also contribute to the recent epidemic. Ideally, an effective ZIKV vaccine should provide sterilizing immunity that blocks the initial viral dissemination to prevent subsequent infection-caused morbidity. Currently, there is no approved ZIKV vaccine for disease prevention. The membrane (M) and envelope protein (E) expressed as prM-E form is a common antigen choice for current vaccine candidates against ZIKV, as neutralizing antibodies (nAb) against prM-E can prevent viral entry. However, such nascent PrM-E based ZIKV vaccines can increase the infectiousness of the dengue virus (DENV), another flavivirus of which endemic area largely overlaps with ZIKV. Due to the high degree of sequence homology between the E proteins of ZIKV and DENV, the ZIKV prM-E vaccine may stimulate the production of antibodies that are non-neutralizing but cross-reactive with the DENV E protein. In the event of a subsequent dengue virus infection, antibody-dependent enhancement (ADE) can occur when the suboptimal anti- ZIKV antibodies bind to the DENV virus, which thereby enhance the entry of DENV into host cells and exacerbate dengue symptoms. Strategies to prevent the induction of ADE-prone antibodies have been described recently for modified ZIKV immunogens, which unfortunately display suboptimal protection efficacy in small animals. Here, we focus on applying structure-based vaccine design to develop novel vaccine candidates with improved immunogenicity and reduced ADE potential for DENV infection. In preliminary study, our lead vaccine candidate formulated in optimized adjuvant showed nearly complete protection in immune mice challenged with ZIKV, and abolished ADE potential assessed by in vitro assays. Potent monoclonal ZIKV nAbs targeting the major ZIKV E protein nAb determinants including the quaternary E-dimer dependent epitope isolated from immune mice confirmed the design rationale. In this application, we will extend our effort via further immunogen designs guided by B cell/antibody response analysis and structural investigation of ZIKV E protein-antibody interactions to improve our lead vaccine candidate aiming at achieving sterilizing immunity, to evaluate in small animal models. If succeeds, this study will contribute to (i) the development of an effective and safe ZIKV vaccine, and (ii) deepening our understanding of immune response to flavivirus infections and immunizations.