Multiepitope circumsporozoite P.falciparum malaria subunit vaccine displayed on v

简要说明 鉴于疟疾给许多发展中国家带来的沉重负担， 一项建议是开发一种恶性疟原虫疟疾特异性免疫原， 预防疟疾的有效疫苗。目前最有效的疟疾候选疫苗（RTS，S/AS 02 A）是 基于使用与疟疾环子孢子（CS）特异性融合的颗粒载体平台（HBsAg）， T和B细胞表位。RTS，S疫苗目前的局限性是需要反应原性 佐剂和瞬时保护。另一个潜在的复杂性是，载体来自人类， 病原体，B型肝炎病毒（HBV）。为了避免这些问题， 已经开发了一个平台，特别是来自土拨鼠嗜肝DNA病毒（WHcAg）的核心蛋白。 修饰的WHcAg颗粒将用作疫苗平台，原因如下： 引起极高水平的抗CS抗体; HBV慢性感染者对HBcAg和HBsAg的免疫耐受 运营商（全球4亿）可以通过使用WHcAg平台来规避;因为CS- WHcAg杂交颗粒可以在细菌中制成，生产疫苗将相对便宜。一 初步的CS-WHcAg杂合颗粒已被开发，其含有两个中和CS重复表位 插入环区（产生最高滴度抗插入抗体的插入位点）和两个 “通用”疟疾特异性T细胞结构域融合到C末端。这种CS-WHcAg混合颗粒非常 在小鼠中具有免疫原性，并且能够引发预防P. 恶性疟原虫/伯氏疟原虫杂交子孢子肝感染，因此，它是一个理想的基础， 研制出一种供人类使用的疫苗开发最佳疟疾疫苗的战略分为四个方面 目的：1）掺入额外的CS衍生的B细胞和T细胞中和表位; 2）测试保护性表位。 候选疫苗在杂交恶性疟原虫/伯氏疟原虫子孢子模型中的效力，并开发 3）测试重组的和化学连接的“分子”抗原决定簇; 佐剂”，因为它们能够提高疫苗颗粒的保护效力;以及4）确定最佳的佐剂组合物， 所选候选疫苗的配方、途径和剂量。这两个强大的组合 技术、WHcAg载体平台和恶性疟原虫/伯氏疟原虫杂交子孢子攻击模型， 将能够生产多种CS-WHcAg杂交颗粒免疫原， 在对恶性疟原虫疟疾特异的体内感染模型系统中的保护效力。

Summary Statement Given the very high burden malaria imposes on many developing countries, the overall objective of this proposal is to develop a P. falciparum malaria-specific immunogen that may be useful as an affordable and effective vaccine to prevent malaria. The current most effective malaria vaccine candidate (RTS,S/AS02A) is based on the use of a particulate carrier platform (the HBsAg) fused to malaria circumsporozoite (CS)-specific T and B cell epitopes. Current limitations of the RTS,S vaccine have been a requirement for reactogenic adjuvants and transient protection. A further potential complication is that the carrier is derived from a human pathogen, the hepatitis B virus (HBV). To circumvent these problems a non-human pathogen-derived carrier platform has been developed, specifically the core protein from the woodchuck hepadnavirus (WHcAg). Modified WHcAg particles will be used as the vaccine platform for several reasons: CS-WHcAg hybrid particles elicit extremely high levels of anti-CS antibodies; the immune tolerance to HBcAg and HBsAg in HBV chronic carriers (400 million worldwide) can be circumvented by the use of the WHcAg platform; and because CS- WHcAg hybrid particles can be made in bacteria, production of a vaccine will be relatively inexpensive. A preliminary CS-WHcAg hybrid particle has been developed that contains two neutralizing CS repeat epitopes inserted into the loop region (the insertion site that raises the highest titer anti-insert antibodies) and two "universal" malaria-specific T cell domains fused to the C-terminus. This CS-WHcAg hybrid particle is very immunogenic in mice and is capable of eliciting neutralizing anti-CS repeat antibodies that prevent P. falciparum/P. berghei hybrid sporozoite liver infection in vivo, therefore it is an ideal basis from which to develop a vaccine for human use. The strategy for developing an optimal malaria vaccine is divided into four aims: 1) incorporation of additional CS-derived B cell and T cell neutralizing epitopes; 2) testing the protective efficacy of the vaccine candidates in a hybrid P. falciparum/P. berghei sporozoite model and developing the model to encompass additional P. falciparum epitopes; 3) test recombinant and chemically linked "molecular adjuvants" for their ability to improve protective efficacy of the vaccine particles; and 4) determine optimal formulation, route and dosing of the chosen vaccine candidates. The combination of these two powerful technologies, the WHcAg-carrier platform and the P. falciparum/P. berghei hybrid sporozoite challenge model, will enable the production of a variety of CS-WHcAg hybrid particle immunogens that can be tested for protective efficacy in an in vivo infectious model system specific for P. falciparum malaria.