Defining viral and immune mechanisms of Dengue virus serotype 2 immune evasion

项目总结 登革病毒(DENV)是目前导致3.9亿人死亡的最重要的节肢动物传播病毒之一 全球范围内的人类感染。登革热病毒可导致流行中的儿童和老年人的严重疾病和死亡 亚洲和拉丁美洲等地区。DENV在基因和血清型上分为四个血清型(1-4) 每种血清型还可以进一步细分为不同的基因型别。令人震惊的是，在接下来的50-80年里， DENV感染预计将蔓延到世界上新的地区，包括美国，使数百万人 有更多的人有患登革热病毒的风险。此外，唯一获得许可的DENV疫苗不起作用 与现有的四种DENV血清型一样好。登革2型新城疫病毒疫苗免疫效果的研究 疫苗的有效率非常低(39%)，强调了改进DENV疫苗设计和策略的必要性。而当 已知DENV的遗传多样性存在于四个血清型之间，DENV内型的作用 在调节疫苗诱导的抗体的中和抗性方面，不同基因型之间的多样性是 不是很清楚。因此，该项目旨在定义自然发生的DENV2基因的作用 中和抗体逃避的变异。该项目还旨在定义Ig G Fc特征，如Ig G NIH疫苗接种者中疫苗诱导的结合和中和抗体的亚类和Fcγ受体结合。至 完成这个项目，我已经生成了一个DENV2基因变异病毒小组使用反向遗传学。 重要的是，这个基因分型小组包含了来自世界不同地区的当代分离株，包括： 亚裔I、亚裔II、亚裔美国人、世界性、非洲和亚裔亚洲分离株。我发现 这些DENV2基因变异体在PRM和E中表现出相当大的氨基酸残基变异 结构域I(EDI)、结构域II(EDII)和结构域III(EDIII)，它们是中和抗体的关键靶点。有趣的是，我的 初步数据表明，在DENV2中观察到的基因类型遗传多样性调节了差异 对DENV2-中和性单抗和多克隆抗体的中和敏感性 被感染的人。因此，我将评估DENV2基因多样性在调节中和中和中的作用 对NIH单价DENV人疫苗和疫苗诱导的中和抗体的耐药性 四价DENV人类疫苗接种者。此外，我还将定义Fc区特征，如Ig G亚类 以及与Fcγ受体的结合，这些疫苗引发的抗体反应在人类中介导保护 登革热病毒感染模型的建立。更好地理解DENV逃避机制(S) 中和抗体将是改善现有DENV2疫苗的关键，因为DENV2疫苗表现不佳。这些 项目调查结果将提供有关DENV2用来颠覆东道主启发的战略的关键信息 中和抗体，这对合理设计旨在改进疫苗的DENV疫苗将是重要的 功效。

Project summary Dengue virus (DENV) is one of the most significant arthropod-borne viruses currently leading to >390 million human infections worldwide. DENV can cause severe disease and death in children and the elderly in endemic regions such as Asia and Latin America. DENV is genetically and serotypically divided into four serotypes (1-4) and each serotype can be further subdivided into distinct genotypes. Alarmingly, in the next 50-80 years, DENV infections are projected to spread to new areas of the world, including the United States, putting millions of additional individuals at risk for DENV disease. Moreover, the only licensed DENV vaccine does not perform equally well against the existing four DENV serotypes. The vaccine efficacy against DENV serotype 2 (DENV2) is remarkably low (39% efficacy), underlining the need to improve DENV vaccine design and strategies. While it is known that DENV genetic diversity exists among the four serotypes, the role of DENV intraserotypic diversity within the distinct genotypes in modulating neutralization resistance to vaccine-elicited antibodies is not well understood. Therefore, this project aims to define the role of naturally occurring DENV2 genetic variation on neutralizing antibody evasion. This project also aims to define IgG Fc characteristics, such as IgG subclass and Fcγ receptor binding, of vaccine-elicited binding and neutralizing antibodies in NIH vaccinees. To complete this project, I have generated a DENV2 genotype variant virus panel using reverse genetics. Importantly, this genotype panel contains contemporary isolates from distinct regions in the world including: Asian I, Asian II, Asian-American, Cosmopolitan, Sylvatic African, and Sylvatic Asian isolates. I discovered that these DENV2 genotypic variants exhibit considerable amino acid residue variability within the prM and in E domain I (EDI), II (EDII), and III (EDIII), which are key targets for neutralizing antibodies. Interestingly, my preliminary data demonstrates that the genotypic genetic diversity observed in DENV2 modulates differential neutralization sensitivity to both neutralizing monoclonal antibodies and polyclonal antibodies from DENV2- infected individuals. I will therefore evaluate the role of DENV2 genetic diversity in modulating neutralization resistance to vaccine-elicited neutralizing antibodies from NIH monovalent DENV human vaccinees and tetravalent DENV human vaccinees. Moreover, I will define the Fc region characteristics, such as IgG subclass and binding to Fcγ receptors, of these vaccine-elicited antibody responses that mediate protection in a human challenge model of DENV infection. A better understanding of the mechanism(s) by which DENV evades neutralizing antibodies will be critical to improve the existing DENV2 vaccine that performs poorly. These project findings will provide crucial information on the strategies that DENV2 employs to subvert host-elicited neutralizing antibodies, which will be important to rationally design DENV vaccines aimed at improving vaccine efficacy.