Institute of Biotechnology, National Tsing Hua University, Hsinchu 30013, Taiwan.
Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 11529, Taiwan.
Theranostics. 2019 Jul 9;9(16):4811-4826. doi: 10.7150/thno.35919. eCollection 2019.
The viral E proteins of dengue virus (DENV) and Zika virus (ZIKV) are the major viral proteins involved in receptor binding and fusion, and for the induction of protective antibodies against viral infections. DIII of the E proteins is an independent domain and stretches out on the virion surface that can elicit type-specific neutralizing antibodies. For recombinant DIII vaccine development, prime-boost immunizations can provide an advantage of eliciting more type-specific neutralizing antibodies by recalling DIII antigens after DIII booster to improve protection. : The DIII of the E genes of DENV and ZIKV were fused with bacterial gene for the expression of flagellin-DIII (FliC-DIII) fusion proteins. Prime-boost immunization strategies by the second-dose booster of four DENV serotype or ZIKV FliC-DIII fusion proteins were used to investigate the induction of neutralizing antibodies and protection against viral infections. Cross-reactive non-neutralizing antibodies in each group of antisera were also examined using antibody-dependent enhancement (ADE) assay. A series of glycan-masking E antigens were finally constructed for prime-boost immunizations to abolish the elicitation of cross-reactive non-neutralizing antibodies for ADE activity. : We showed that inclusion of a bivalent live-attenuated vaccine with a FliC-DIII booster is superior in eliciting neutralization titers and protection against all four-serotype DENVs. We also demonstrated that recombinant adenovirus vectors encoding four-serotype DENV prMEs with a FliC-DIII prime-boost scheme is capable of eliciting good antibody responses. In contract, recombinant adenovirus vector of ZIKV prME gene priming, followed by ZIKV FliC-DIII booster did not improve vaccine efficacy. The glycan-masking mutation on the ZIKV E protein ij loop (E-248NHT), but not on DENV2 E protein ij loop (E-242NHT), resulted in abolishing the elicitation of cross-reactive antibodies for DENV and ZIKV infection enhancements. : Our findings can provide useful information for designing novel immunogens and vaccination strategies in an attempt to develop a safe and efficacious DENV or ZIKV vaccine.
登革热病毒（DENV）和寨卡病毒（ZIKV）的病毒 E 蛋白是参与受体结合和融合的主要病毒蛋白，并诱导针对病毒感染的保护性抗体。E 蛋白的 DIII 是一个独立的结构域，伸展在病毒粒子表面，可以引发针对特定类型的中和抗体。为了开发重组 DIII 疫苗，初免-加强免疫可以通过在 DIII 加强后召回 DIII 抗原来提供诱导更多针对特定类型的中和抗体的优势，以提高保护效果。我们将 DENV 和 ZIKV 的 E 基因的 DIII 与细菌 flagellin 基因融合，用于表达鞭毛蛋白-DIII（FliC-DIII）融合蛋白。我们使用四价 DENV 血清型或 ZIKV FliC-DIII 融合蛋白的第二剂加强来研究中和抗体的诱导和对病毒感染的保护作用。还使用抗体依赖性增强（ADE）测定法检查了每组抗血清中的交叉反应性非中和抗体。最后，构建了一系列糖基掩蔽的 E 抗原用于初免-加强免疫，以消除 ADE 活性的交叉反应性非中和抗体的产生。我们表明，包含单价减毒活疫苗和 FliC-DIII 加强剂的方案在诱导中和滴度和对所有四价 DENVs 的保护方面优于单价减毒活疫苗。我们还证明，编码四价 DENV prME 的重组腺病毒载体与 FliC-DIII 初免-加强方案一起能够引发良好的抗体反应。相比之下，用重组腺病毒载体 ZIKV prME 基因进行初免，然后用 ZIKV FliC-DIII 进行加强，并没有提高疫苗的功效。ZIKV E 蛋白 ij 环上的糖基掩蔽突变（E-248NHT），而不是 DENV2 E 蛋白 ij 环上的突变（E-242NHT），导致消除了对 DENV 和 ZIKV 感染增强的交叉反应性抗体的产生。我们的研究结果可以为设计新型免疫原和接种策略提供有用的信息，以试图开发安全有效的 DENV 或 ZIKV 疫苗。
