A VEE Replicon-Based Vaccine for Dengue Virus

描述(由申请人提供)： 登革病毒(DEN)是美国国立卫生研究院/美国疾病控制与预防中心列出的与生物恐怖主义有关的病原体和新出现的病原体名单上的优先“A”病原体，它感染人类，导致一系列临床症状，包括登革热、登革出血热和登革热休克综合征。严重疾病与不同血清型的第二次感染或感染母体抗体的婴儿有关。开发有效的登革热疫苗面临的挑战之一是在面对母体抗体时诱导主动免疫，这也是麻疹和其他疾病疫苗面临的问题。我们假设，即使在被动转移的中和抗DEN抗体存在的情况下，基于非传播性委内瑞拉马脑炎病毒载体(VRP)的DEN疫苗也能够在幼鼠中诱导内源性免疫反应。我们的假设基于VEE载体的三个特性：(I)DEN抗原不会暴露在VRP表面；(Ii)VRP会将编码抗原的基因靶向淋巴结，促进和增强抗原提呈；(Iii)非传播性VRP载体通过在单轮感染中高水平表达异源基因来免疫。在这项探索性拨款中，我们建议1)表征表达DEN2PRM和E膜蛋白的VRP原型疫苗在断奶小鼠中诱导的基线体液和细胞介导的免疫反应；2)确定原型疫苗在被动转移的中和抗登革热抗体的存在下，在断奶小鼠中诱导内源性免疫反应的能力；以及3)修改VRP表达的DEN2PRM和E蛋白的细胞内靶向，以提高小鼠的表达水平和免疫原性。这些实验将证明VRP方法用于四价登革热疫苗的可行性，同时建议解决包括麻疹在内的其他婴儿疫苗遇到的类似母体抗体困难的问题。

DESCRIPTION (provided by applicant): Dengue virus (DEN), a priority "A" pathogen on the NIH/CDC list of bioterrorism related and emerging pathogens, infects humans causing a spectrum of clinical manifestations including dengue fever, dengue hemorrhagic fever and dengue shock syndrome. Severe disease is associated with a second infection with a different serotype or infection of infants harboring maternal antibodies. One of the challenges to development of an effective DEN vaccine is to induce active immunity in the face of maternal antibodies, a problem also facing vaccines for measles and other diseases. We hypothesize that a vaccine for DEN based on non-propagating Venezuelan equine encephalitis virus vectors (VRP) will be able to induce an endogenous immune response in young mice, even in the presence of passively transferred neutralizing anti-DEN antibodies. We base our hypothesis on three properties of the VEE vectors, (i) The DEN antigens will not be exposed on the VRP surface, (ii) VRP will target the antigen-encoding gene to the lymph node, facilitating and enhancing antigen presentation, (iii) Non-propagating VRP vectors immunize by expressing high levels of the heterologous gene only in a single round of infection. In this exploratory grant we propose to 1) Characterize the baseline humoral and cell-mediated immune responses induced by a prototype VRP vaccine expressing DEN2 prM and E membrane proteins in weanling mice; 2) Determine the ability of the prototype vaccine to induce an endogenous immune response in weanling mice in the presence of neutralizing anti-dengue antibodies passively transferred by inoculation or by suckling on immune dams; and 3) Modify the intracellular targeting of the VRP-expressed DEN2 prM and E proteins to improve expression levels and immunogenicity in mice. These experiments will demonstrate the feasibility of a VRP approach to a tetravalent DEN vaccine while suggesting solutions to similar difficulties with maternal antibodies encountered with other infant vaccines including measles.