Novel Tetravalent Vaccines for Dengue Virus

描述（由申请人提供）：登革热病毒感染是一种新出现的疾病和一个不断扩大的全球健康问题。在热带和亚热带地区，超过三分之一的世界人口面临传播风险，疫苗是一项紧迫的公共卫生优先事项。虽然登革热很少发生在美国大陆，但它在波多黎各以及拉丁美洲和东南亚的许多热门旅游目的地流行。因此，前往登革热流行地区的个人也需要接种疫苗。开发登革热疫苗的一个主要问题是存在四种共循环血清型。不同血清型的连续感染可引起被称为登革出血热的强化疾病。理想情况下，登革热疫苗应同时或在短时间内预防所有血清型。临床试验中最先进的登革热疫苗是一种由四种减毒活病毒组成的复杂混合物，需要一个覆盖12个月的免疫计划才能实现完全的血清转化。登革热病毒的包膜(E)蛋白是病毒毒力的主要决定因素，也是中和和增强抗体的主要靶点。E蛋白与较小的膜(M)蛋白可以形成病毒样颗粒（vlp）。Altravax拥有几种新型登革热包膜变体，作为DNA疫苗，可以在猴子体内单独诱导针对所有四种登革热血清型的中和抗体。从这些新的四价登革热E蛋白序列开始，我们建议生产重组VLPs作为候选疫苗。VLPs是一种多蛋白结构，模仿真实的天然病毒的组织和构象，但缺乏病毒基因组。过去批准的疫苗（HBV、HPV）的经验表明，重组VLPs是有效的免疫原，其安全性是减毒活病毒难以达到的。我们会评估

DESCRIPTION (provided by applicant): Dengue virus infection is an emerging disease and an expanding global health problem. More than one-third of the world's population is at risk for transmission in tropical and subtropical areas and vaccines are an urgent public health priority. Although dengue rarely occurs in the continental United States, it is endemic in Puerto Rico, and in many popular tourist destinations in Latin America and Southeast Asia. Vaccines are therefore also required for individuals traveling to areas where dengue is endemic. A major problem in developing vaccines for dengue is the existence of four co-circulating serotypes. Sequential infections by different serotypes can cause an enhanced disease known as dengue hemorrhagic fever. Ideally, dengue vaccines should protect against all serotypes simultaneously or within a short time period. The most advanced dengue vaccine in clinical testing is a complex mixture of four live-attenuated viruses that requires an immunization schedule covering 12 months to achieve full seroconversion. The envelope (E) protein of dengue virus is the main determinant of virulence and is the major target of neutra- lizing and enhancing antibodies. The E protein, along with the smaller membrane (M) protein can form virus- like particles (VLPs). Altravax possesses several novel dengue envelope variants that, as DNA vaccines, can individually induce neutralizing antibodies to all four dengue serotypes in monkeys. Beginning with these novel tetravalent dengue E protein sequences, we propose to produce recombinant VLPs as vaccine candidates. VLPs are multiprotein structures that mimic the organization and conformation of authentic native viruses but lack the viral genome. Past experience with approved vaccines (HBV, HPV) has shown that recombinant VLPs are potent immunogens and offer a level of safety that is difficult to achieve with live-attenuated viruses. We will evaluate mammalian, insect, and yeast systems for optimal expression of dengue VLPs. Care will be taken at this early stage to ensure that the cell lines, systems, and methods developed can ultimately be transferred to GMP manufacture. We will prepare monoclonal antibodies both to study the mechanism of tetravalent immunogenicity and to provide reagents for manufacturing controls for later work. We will evaluate VLP preparations in mice with several different adjuvant systems. Such additives can influence the isotypes of antibodies produced as well as stimulate more potent neutralizing antibody responses. Since a critical part of dengue vaccine development concerns possible disease enhancement, which is thought to be antibody- dependent in humans, we will undertake a collaboration destined to investigate these phenomena in a mouse line (AG129) that is an in vivo model of antibody-dependent severe dengue disease. The ultimate objective is to develop a safe preventative vaccine for dengue based on a single recombinant tetravalent VLP-based immunogen in a highly immunogenic format. To assist us in this work, we have assembled a team of consul- tants and collaborators with expertise in many different fields of dengue virology, immunology, and pathology.