Thiono Devina J, Samaras Demetrios, Phan Thanh T N, Zhu Deanna R, Shah Ruby P, Castillo Izabella, Forsberg Lawrence J, Premkumar Lakshmanane, Baric Ralph S, Tian Shaomin, Kuhlman Brian, de Silva Aravinda M
Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA.
Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina, USA.
J Virol. 2025 May 20;99(5):e0022925. doi: 10.1128/jvi.00229-25. Epub 2025 Apr 16.
The four dengue virus (DENV) serotypes cause several hundred million infections annually. Several live-attenuated tetravalent dengue vaccines (LAVs) are at different stages of clinical testing and regulatory approval. A major hurdle faced by the two leading LAVs is uneven replication of vaccine serotypes stimulating a dominant response to one serotype at the expense of the other three, leading to the potential for vaccine antibody (Ab)-enhanced, more severe infections by wild-type (WT) DENV serotypes that fail to replicate in the vaccine. Protein subunit vaccines are a promising alternative since antigen dosing can be precisely controlled. However, DENV envelope (E) protein subunit vaccines have not performed well to date, possibly due to differences between the monomeric structure of soluble E and the E homodimer of the viral surface. Previously, we have combined structure-guided computational and experimental approaches to design and produce DENV2 E antigens that are stable homodimers at 37℃ and stimulate higher levels of neutralizing Abs (NAbs) than the WT E antigen in mice. The goal of this study was to evaluate if DENV2 E homodimers stimulate NAbs that target different epitopes on E protein compared to the WT E monomer. Using DENV4/2 chimeric viruses and Ab depletion methods, we mapped the WT E-elicited NAbs to simple epitopes on domain III of E. In contrast, the stable E homodimer stimulated a more complex response toward all three surface-exposed domains of the E protein. Our findings highlight the impact of DENV2 E oligomeric state on the quality and specificity of DENV NAbs and the promise of DENV E homodimers as subunit vaccines.IMPORTANCEThe ideal dengue virus (DENV) vaccine should elicit a balanced and highly protective immune response against all four DENV serotypes. Current tetravalent live-attenuated DENV vaccines have faced challenges due to uneven replication of vaccine virus strains stimulating a strong immune response to one serotype and weak responses to the other three. Protein subunit vaccines provide novel opportunities to stimulate a balanced response because dosing can be precisely controlled and independent of vaccine virus replication. Here, we compare immune responses elicited by a new DENV serotype 2 protein vaccine designed to match the structure of proteins on the viral surface. We find that proteins designed to match the viral surface stimulate better immune responses targeting multiple sites on the viral surface compared to previous protein vaccines. Our results justify further testing and development of these second-generation DENV protein subunit vaccines.
四种登革病毒（DENV）血清型每年导致数亿人感染。几种减毒活四价登革疫苗（LAV）正处于临床试验和监管审批的不同阶段。两种领先的LAV面临的一个主要障碍是疫苗血清型的复制不均衡，从而刺激对一种血清型产生主导反应，而牺牲了其他三种血清型，这就导致了疫苗抗体（Ab）增强野生型（WT）DENV血清型感染的可能性，而这些血清型在疫苗中无法复制。蛋白质亚单位疫苗是一种有前景的替代方案，因为抗原剂量可以精确控制。然而，DENV包膜（E）蛋白亚单位疫苗迄今为止表现不佳，可能是由于可溶性E的单体结构与病毒表面的E同型二聚体之间存在差异。此前，我们结合了结构导向的计算和实验方法来设计和生产在37℃下为稳定同型二聚体的DENV2 E抗原，并且在小鼠中刺激产生的中和抗体（NAb）水平高于WT E抗原。本研究的目的是评估与WT E单体相比，DENV2 E同型二聚体是否能刺激靶向E蛋白上不同表位的NAb。使用DENV4/2嵌合病毒和抗体去除方法，我们将WT E诱导的NAb定位到E结构域III上的简单表位。相比之下，稳定的E同型二聚体对E蛋白所有三个表面暴露结构域产生了更复杂的反应。我们的研究结果突出了DENV2 E寡聚状态对DENV NAb质量和特异性的影响，以及DENV E同型二聚体作为亚单位疫苗的前景。重要性理想的登革病毒（DENV）疫苗应引发针对所有四种DENV血清型的平衡且高度保护性的免疫反应。目前的四价减毒活DENV疫苗面临挑战，因为疫苗病毒株的复制不均衡，刺激对一种血清型产生强烈免疫反应，而对其他三种血清型产生微弱反应。蛋白质亚单位疫苗提供了刺激平衡反应的新机会，因为剂量可以精确控制且与疫苗病毒复制无关。在这里，我们比较了一种旨在匹配病毒表面蛋白质结构的新型DENV 2型蛋白质疫苗引发的免疫反应。我们发现，与之前的蛋白质疫苗相比，旨在匹配病毒表面的蛋白质能刺激针对病毒表面多个位点的更好免疫反应。我们的结果为进一步测试和开发这些第二代DENV蛋白质亚单位疫苗提供了依据。
