Multi-target blood stage vaccine against Plasmodium falciparum

项目摘要 本申请的总体目标是推进PfCDPK 5和PfGARP作为疫苗候选物， 恶性疟疾恶性疟原虫疟疾影响了世界上几乎一半的人口， 每年有超过五十万人死亡非洲疟疾流行区的幼儿死亡率最高 因为他们的免疫系统不成熟。全球控制这种疾病的努力有限 目前还没有疫苗被批准用于临床。因此，迫切需要 发现新的候选疫苗。预防儿童疟疾的疫苗是一个优先事项，因为年龄低于 5岁以下的儿童非常容易患上这种疾病。在最近的研究中，我们的实验室发现裂殖体 出口抗原-1（PfSEA-1），一种244 kDa的寄生虫抗原，对于寄生虫从感染的红细胞中排出至关重要。 血细胞（iRBC），这是作为一个全面的，全长的研究文章发表在科学。 在一个平行的方法中，我们筛选了从寄生虫构建的噬菌体展示cDNA文库， 在我们的坦桑尼亚现场分离，有/无培养适应，使用抗体阳性选择 从抗药的两岁儿童中汇集抗体，从易感儿童中汇集抗体进行阴性选择。 我们鉴定了几个编码恶性疟原虫谷氨酸REACH蛋白的独立cDNA克隆 （PfGARP）和植物样钙依赖性蛋白激酶（PfCDPK 5），它们被 抗体，但不敏感的血清。我们的初步数据表明，PfGARP和PfCDPK 5 分别对寄生虫在侧RBC中发育和排出至关重要）。PfGARP表达于 滋养体感染的RBC和PfCDPK 5在裂殖子从红细胞破裂时由裂殖子表达。 抗PfGARP和PfCDPK 5的抗体在体外阻断寄生虫生长高达99%， CDPK 5保护小鼠免于寄生虫血症，并延长用致死性伯氏疟原虫ANKA攻击的小鼠的存活。 我们的疫苗发现计划也鉴定了几种已知的入侵配体（MSP-4和MSP-7 在本申请中，我们将用CDPK 5评价这些候选疫苗， 单一融合蛋白（PfCDPK 5-MSP 4和PfCDPK 5-MSP 7）与PfGARP的组合， 在小鼠疫苗试验中使用多种佐剂系统。将进一步评价先导融合抗原， 在鼠模型中使用TFRS耗竭方法的细胞介导的免疫应答。本研究的可交付成果 将是一种佐剂优化的三价疫苗，可用于Aotus/ P. falciparum攻毒和1期临床试验。 在人体内进行的试验，目标是进入，细胞内发育和寄生虫周期的退出。

Project Summary The overall aim of this application is to advance PfCDPK5 and PfGARP as vaccine candidates for falciparum malaria. P.falciparum malaria affects almost one-half of the world's population and causes more than 500,000 deaths annually. Young children in malaria endemic areas of Africa have the highest mortality rate because of their immature immune systems. Global efforts to control the disease have had limited success, and no vaccine has yet been approved for clinical use. Therefore, there is an urgent, unmet need to discover new vaccine candidates. A vaccine against childhood malaria is a priority because children below the age of 5 years are highly vulnerable to the disease. In recent studies, our laboratory discovered Schizont Egress Antigen-1 (PfSEA-1), a 244-kDa-parasite antigen that is crucial for parasite egress from an infected red blood cell (iRBC), which was published as a comprehensive, full-length Research Article in Science. In a parallel approach, we have screened phage display cDNA libraries constructed from parasites isolated at our Tanzanian field site with/without culture adaptation using positive selection with antibodies pooled from resistant two-year-olds and negative selection with antibodies pooled from susceptible children. We identified several independent cDNA clones encoding plasmodium falciparum glutamic acid reach protein (PfGARP) and plant-like calcium-dependent protein kinase (PfCDPK5) that were uniquely recognized by antibodies in resistant, but not susceptible sera. Our preliminary data demonstrate that PfGARP and PfCDPK5 is critical for parasite development in side RBC and egress respectively). PfGARP expresses on the surface of the trophozoite infected RBC and PfCDPK5 is expressed by merozoites as they rupture from erythrocytes. Antibodies against PfGARP and PfCDPK5 block parasite growth up to 99% in vitro, and ortholog vaccine of CDPK5 protect mice from parasitemia, and extend the survival of mice challenged with lethal P. berghei ANKA. Our vaccine discovery program has also identified several known invasion ligands (MSP-4 and MSP-7 collectively referred to as MSPs) In this application, we will evaluate these vaccine candidates with CDPK5 as single fusion protein (PfCDPK5-MSP4 & PfCDPK5-MSP7) in combination with PfGARP in in vitro assays and using multiple adjuvant systems in murine vaccine trials. The lead fusion antigen will be further evaluated for cell mediated immune response using TFRS depletion method in murine model. The deliverables from this study will be an adjuvant optimized tri-valent vaccine ready for Aotus/ P. falciparum challenge and Phase-1 clinical trial in human that targets the entry, intracellular development, and the exit of the parasite cycle in .