Meganck Rita M, Zhu Deanna, Dong Stephanie, Snoderly-Foster Lisa J, Dalben Yago R, Thiono Devina, White Laura J, DeSilva Aravinda M, Baric Ralph S, Tse Longping V
Department of Molecular Microbiology and Immunology, Saint Louis University.
Department of Epidemiology, University of North Carolina at Chapel Hill.
bioRxiv. 2023 Aug 4:2023.03.22.533803. doi: 10.1101/2023.03.22.533803.
A hallmark of Dengue virus (DENV) pathogenesis is the potential for antibody-dependent enhancement, which is associated with deadly DENV secondary infection, complicates the identification of correlates of protection, and negatively impacts the safety and efficacy of DENV vaccines. ADE is linked to antibodies targeting the fusion loop (FL) motif of the envelope protein, which is completely conserved in mosquito-borne flaviviruses and required for viral entry and fusion. In the current study, we utilized saturation mutagenesis and directed evolution to engineer a functional variant with a mutated FL (D2-FL) which is not neutralized by FL-targeting monoclonal antibodies. The FL mutations were combined with our previously evolved prM cleavage site to create a mature version of D2-FL (D2-FLM), which evades both prM- and FL-Abs but retains sensitivity to other type-specific and quaternary cross-reactive (CR) Abs. CR serum from heterotypic (DENV4) infected non-human primates (NHP) showed lower neutralization titers against D2-FL and D2-FLM than isogenic wildtype DENV2 while similar neutralization titers were observed in serum from homotypic (DENV2) infected NHP. We propose D2-FL and D2-FLM as valuable tools to delineate CR Ab subtypes in serum as well as an exciting platform for safer live attenuated DENV vaccines suitable for naïve individuals and children.
登革病毒（DENV）发病机制的一个标志是抗体依赖性增强的可能性，这与致命的DENV二次感染相关，使保护性相关因素的鉴定复杂化，并对DENV疫苗的安全性和有效性产生负面影响。ADE与靶向包膜蛋白融合环（FL）基序的抗体有关，该基序在蚊媒黄病毒中完全保守，是病毒进入和融合所必需的。在本研究中，我们利用饱和诱变和定向进化技术构建了一个具有突变FL（D2-FL）的功能变体，该变体不会被靶向FL的单克隆抗体中和。将FL突变与我们之前进化的prM切割位点相结合，创建了一个成熟版本的D2-FL（D2-FLM），它既能逃避prM抗体和FL抗体，又能保持对其他型特异性和四级交叉反应（CR）抗体的敏感性。来自异型（DENV4）感染的非人灵长类动物（NHP）的CR血清对D2-FL和D2-FLM的中和效价比同基因野生型DENV2低，而在同型（DENV2）感染的NHP血清中观察到相似的中和效价。我们提出D2-FL和D2-FLM是描绘血清中CR抗体亚型的有价值工具，也是适合初免个体和儿童的更安全的减毒活DENV疫苗的令人兴奋的平台。
