Development of a Tetravalent Dengue Vaccine that Links Innate and Adaptive Immuni

描述(由申请人提供)：我们建议开发一种四价登革热(DEN)疫苗，采用一种新的策略，确保对登革热病毒感染的广泛保护。登革热是由四种由蚊子传播的血清学上相关的黄病毒引起的，开发登革热疫苗尤其具有挑战性，因为不同登革热血清型/病毒的顺序感染可导致登革热出血热(DHF)或登革热休克综合征(DSS)，这两种疾病都会危及生命。由于这种现象，一种有效和安全的疫苗需要是四价的，并同时提供对所有四种登革热病毒的保护性免疫。到目前为止，由于干扰、免疫原性差和产生不平衡的免疫反应等问题，开发四价活疫苗或减毒疫苗的尝试都失败了。在这里，我们提出了一种创新的登革热疫苗策略，旨在克服这些限制。我们的方法包括通过将保护性抗原连接到Toll样受体(TLR)配体，将重组蛋白的混合物靶向抗原提呈细胞。TLR与其相关配体的结合触发了先天免疫系统，并启动了一系列影响适应性免疫反应的事件。这消除了疫苗配方中通常使用的佐剂或载体的需要，并通过在不增加毒性的情况下增强免疫原性来提高疫苗效力。通过这一策略，我们成功地开发出了流感和西尼罗河(WN)疫苗候选疫苗，这种疫苗可以经济地生产，诱导强大的抗体反应，在小鼠模型中有效，并且不需要佐剂。该提议的目标是通过设计四种单价融合蛋白来开发四价DEN疫苗，该融合蛋白由来自每个DEN病毒的包膜蛋白的DEN EIII结构域组成，与细菌鞭毛蛋白融合，细菌鞭毛蛋白是一种有效的TLR5配体。为了评估对DEN病毒类型特异性中和抗体的诱导，将在小鼠身上检查对每个单价候选疫苗的免疫反应的有效性和特异性。这些单价研究将指导临床前四价配方的鉴定，该配方将涉及所有四种融合蛋白的混合物，其比例是诱导公平的免疫反应所必需的。四价组合将在小鼠身上进行优化，并作为概念验证在非人类灵长类挑战模型中进行测试。我们假设，所有四种单价蛋白的鸡尾酒配方将诱导平衡的四价免疫反应，并提供针对所有四种DEN病毒的特定类型保护，而不会产生可能增强DEN感染和导致DHF的抗体的风险。

DESCRIPTION (provided by applicant): We propose to develop a tetravalent dengue (DEN) vaccine using a novel strategy that will ensure broad protection against DEN virus infection. The disease dengue is caused by four mosquito-borne serologically related flaviviruses and development of a DEN vaccine has been particularly challenging because sequential infection by different DEN serotypes/viruses can lead to DEN hemorrhagic fever (DHF) or dengue shock syndrome (DSS), both of which are life-threatening. As a consequence of this phenomenon, an efficacious and safe vaccine needs to be tetravalent and provide protective immunity simultaneously against all four DEN viruses. Attempts at developing a tetravalent live or attenuated vaccine have thus far failed due to problems with interference, poor immunogenicity and generation of an imbalanced immune response. Here, we present an innovative DEN vaccine strategy designed to overcome these limitations. Our approach involves targeting a mixture of recombinant proteins to antigen-presenting cells by linking a protective antigen to a Toll-like receptor (TLR) ligand. Engagement of a TLR with its associated ligand triggers the innate immune system and initiates a series of events that impact the adaptive immune response. This eliminates the need for adjuvants or carriers typically used in vaccine formulations and increases vaccine potency by enhancing immunogenicity without increasing toxicity. With this strategy, we have successfully developed influenza and West Nile (WN) vaccine candidates that can be produced economically, induce potent antibody responses, are efficacious in mouse models and do not require adjuvant. The goal of this proposal is to develop a tetravalent DEN vaccine by engineering four monovalent fusion proteins comprised of the DEN EIII domain of the envelope protein from each DEN virus fused to bacterial flagellin, a potent TLR5 ligand. To assess induction of DEN virus type-specific neutralizing antibodies, the efficacy and specificity of the immune response to each monovalent vaccine candidate will be examined in mice. These monovalent studies will guide identification of a preclinical tetravalent formulation that will involve a mixture of all four fusion proteins at ratios necessary to induce an equitable immune response. A tetravalent combination will be optimized in mice and tested in a non-human primate challenge model as proof-of-concept. We hypothesize that a cocktail formulation of all four monovalent proteins will induce a balanced tetravalent immune response and provide type-specific protection against all four DEN viruses without the risk of producing antibodies that may enhance DEN infection and lead to DHF.