Novel Tetravalent Vaccines for Dengue Virus

描述（由申请人提供）：登革病毒感染是一种新兴疾病，也是一个不断扩大的全球健康问题。世界上超过三分之一的人口在热带和亚热带地区面临传播风险，疫苗是紧迫的公共卫生优先事项。虽然登革热在美国大陆很少发生，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称为登革出血热的增强型疾病。理想情况下，登革热疫苗应同时或在短时间内保护所有血清型。临床试验中最先进的登革热疫苗是四种减毒活病毒的复杂混合物，需要12个月的免疫接种计划才能实现完全血清转化。登革病毒的包膜蛋白（E）是登革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蛋白沿着较小的膜（M）蛋白可形成病毒样颗粒（VLP）. Altravax拥有几种新的登革热包膜变异体，作为DNA疫苗，可以单独诱导猴子产生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E蛋白序列开始，我们建议生产重组VLP作为候选疫苗。VLP是模拟真实天然病毒的组织和构象但缺乏病毒基因组的多蛋白结构。过去批准的疫苗（HBV、HPV）的经验表明，重组VLP是有效的免疫原，并提供了减毒活病毒难以达到的安全水平。我们将评估 哺乳动物、昆虫和酵母系统，用于登革VLP的最佳表达。在此早期阶段应注意确保开发的细胞系、系统和方法最终可转移至GMP生产。我们将制备单克隆抗体，以研究四价免疫原性的机制，并为以后的工作提供生产对照品的试剂。我们将在小鼠中用几种不同的佐剂系统评价VLP制剂。这些添加剂可以影响产生的抗体的同种型以及刺激更有效的中和抗体应答。由于登革热疫苗开发的一个关键部分涉及可能的疾病增强，这被认为是抗体依赖性的人类，我们将进行一项合作，目的是在小鼠系（AG129）中研究这些现象，这是抗体依赖性严重登革热疾病的体内模型。最终目标是开发一种安全的登革热预防疫苗，该疫苗基于单一重组四价基于VLP的免疫原，具有高度免疫原性。为了协助我们开展这项工作，我们组建了一个顾问和合作者团队，他们在登革热病毒学、免疫学和病理学的许多不同领域具有专业知识。 公共卫生相关性：登革热病毒感染是一个不断扩大的全球健康问题，每年有多达1亿人感染。目前的候选疫苗是复杂的混合物，包括所有四种登革热类型。我们建议使用新型四价免疫原开发一种更简单的单组分疫苗。

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. PUBLIC HEALTH RELEVANCE: Dengue virus infection is an expanding global health problem and as many as 100 million people are infected yearly. Current vaccine candidates are complex mixtures that include all four dengue types. We propose to develop a much simpler single-component vaccine using novel tetravalent immunogens.