Department of Molecular Biology and the Institute for Molecular Biology and Genetics, Jeonbuk National University, Jeonju, 54896, Republic of Korea.
Innovative Research and Education Center for Integrated Bioactive Materials and the Department of Bioactive Material Sciences, Jeonbuk National University, Jeonju, 54896, Republic of Korea.
J Microbiol. 2023 Jan;61(1):131-143. doi: 10.1007/s12275-023-00021-z. Epub 2023 Feb 1.
Dengue virus (DENV), belonging to the family Flaviviridae, is the causative agent of dengue and comprises four serotypes. A second heterologous DENV infection is a critical risk factor for severe dengue, and no effective vaccine is available to prevent infection by all four DENV serotypes. Recombinant DENV vaccines are primarily based on the envelope proteins, prM and E. The E protein and its envelope domain III (EDIII) have been investigated as candidate antigens (Ags) for recombinant subunit vaccines. However, most EDIII-based Ags are monomers that do not display the cognate antigenic structure of E protein, which is essential for induction of virus-neutralizing immunity. Here, we developed recombinant DENV-2 envelope domain (r2ED) protein as an Ag that mimics the quaternary structure of E protein on the DENV surface. We confirmed that r2ED retained the conformational epitope displayed at the E-dimer interface, which reportedly exhibits broad virus-neutralizing capacity, without displaying the fusion loop epitope that causes antibody (Ab)-dependent enhancement. Furthermore, compared with EDIII alone, r2ED elicited stronger Ag-specific and cross-reactive neutralizing Ab and T cell-mediated immune responses in mice. This Ag-specific immunity was maintained at an elevated level 6 months after the last immunization, suggesting sustained Ag-specific immune memory. Taken together, these observations suggest that r2ED could be used to develop an improved subunit vaccine capable of inducing a broadly cross-reactive and long-lasting immune response against DENV infection.
登革病毒（DENV）属于黄病毒科，是登革热的病原体，包含四个血清型。二次感染不同血清型的登革病毒是导致重症登革热的关键危险因素，目前尚无有效的疫苗可预防四种血清型的登革病毒感染。重组登革病毒疫苗主要基于包膜蛋白、prM 和 E 蛋白。E 蛋白及其包膜结构域 III（EDIII）已被作为重组亚单位疫苗的候选抗原（Ag）进行研究。然而，大多数基于 EDIII 的 Ag 是单体，不能展示 E 蛋白的同源抗原结构，而这对于诱导病毒中和免疫至关重要。在这里，我们开发了重组登革病毒 2 型包膜结构域（r2ED）蛋白作为一种 Ag，可模拟登革病毒表面 E 蛋白的四聚体结构。我们证实 r2ED 保留了在 E 二聚体界面上展示的构象表位，据报道该表位具有广泛的病毒中和能力，而不展示导致抗体（Ab）依赖性增强的融合环表位。此外，与 EDIII 单独使用相比，r2ED 在小鼠中引发了更强的 Ag 特异性和交叉反应性中和 Ab 和 T 细胞介导的免疫应答。这种 Ag 特异性免疫在最后一次免疫后 6 个月仍保持在较高水平，表明持续的 Ag 特异性免疫记忆。总之，这些观察结果表明，r2ED 可用于开发一种改进的亚单位疫苗，能够诱导针对登革病毒感染的广泛交叉反应和持久的免疫应答。
