Anti-flavivirus B cell response analysis to aid vaccine design

寨卡病毒(Zika Virus，ZIKV)是黄病毒家族中的一员，作为一种感染性物质出现，引起 最近疫情期间的全球卫生危机。寨卡病毒感染可导致格林-巴利综合征 在成人中，以及严重的胎儿神经畸形和妊娠期胎儿死亡。寨卡病毒感染 主要通过蚊子叮咬传播，而性传播和垂直传播 感染孕妇对胎儿的感染也是造成最近疫情的原因之一。理想情况下，一辆高效的ZIKV 疫苗应提供灭菌免疫力，阻止最初的病毒传播，以防止 随后感染引起的发病率。目前，还没有获得批准的寨卡病毒疫苗。 预防。膜(M)和包膜蛋白(E)以PRM-E形式表达是一种常见的 当前ZIKV候选疫苗的抗原选择，作为中和抗体(NAB) 抗PRM-E可以防止病毒进入。然而，这种基于PRM-E的新生ZIKV疫苗可以 增加登革热病毒(DENV)的传染性，登革热病毒是另一种黄病毒， 在很大程度上与ZIKV重叠。由于E蛋白之间的高度序列同源性 对于ZIKV和DENV，ZIKV PRM-E疫苗可能刺激抗体的产生 不中和，但与DENV E蛋白发生交叉反应。如果随后发生登革热 病毒感染时，抗体依赖增强(ADE)可发生在次优抗- ZIKV抗体与DENV病毒结合，从而促进DENV进入宿主细胞 并加剧登革热症状。预防易诱发ADE抗体的策略 最近描述了改进的ZIKV免疫原，不幸的是，它显示了 对小动物的保护效果不佳。在这里，我们重点介绍基于结构的应用 疫苗设计以开发新的候选疫苗，提高免疫原性并减少 有可能感染新城疫病毒。在初步研究中，我们的主要候选疫苗是在 优化的佐剂在ZIKV攻击的免疫小鼠中显示出几乎完全的保护作用， 并取消体外测定的ADE电位。强效单抗ZIKV nabs靶向研究 ZIKV E蛋白NAB的主要决定因素包括四元E-二聚体依赖的表位 从免疫小鼠身上分离出来的实验证实了这一设计原理。在此应用程序中，我们将扩展我们的 以B细胞/抗体反应分析和结构分析为指导的进一步免疫原设计的努力 研究ZIKV E蛋白与抗体的相互作用以提高我国领先候选疫苗的靶向性 在实现无菌免疫方面，在小动物模型上进行评价。如果成功，这项研究将 有助于(I)开发有效和安全的寨卡病毒疫苗，以及(Ii)深化我们的 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.