Multi-stage multi-antigen Vaccine for interrupting Malaria Transmission

描述（由申请方提供）：我们认为根除疟疾是可以实现的，但如果没有阻断疟疾传播的强效疫苗（VIMT），就无法根除疟疾。一个合乎逻辑和有前途的策略是联合收割机结合多个阶段的靶抗原，以有效地防止传播。为了预防传播，疫苗应该针对生命周期的红细胞前期（子孢子和肝脏阶段）和性蚊阶段。理想的疟疾疫苗将通过靶向至少红细胞前期（子孢子和肝阶段）和最佳地也靶向寄生虫生命周期的其他阶段来预防感染、疾病和传播。红细胞前阶段疫苗开发基于以下观察结果：通过感染恶性疟原虫（Pf）子孢子（SPZ）的辐照蚊子叮咬进行免疫接种可提供高水平保护。环子孢子蛋白（CSP）是用辐照SPZ免疫小鼠发现的。与PfCSP相比，用放射减毒PfSPZ免疫的志愿者具有识别用于动合子和子孢子的Pf细胞穿越蛋白（PfCelTOS）的T细胞的百分比更高，并且用PfCelTOS免疫小鼠保护小鼠免受在红细胞前期阶段用啮齿动物疟疾SPZ的攻击。我们已经发现，通过用重组（r）PfCelTOS与佐剂免疫小鼠诱导的抗体在体内抑制Pf在蚊子中发育成卵囊，并且在体外抑制PfSPZ在肝细胞中的侵袭和发育。当用单独的rPfCelTOS、单独的rPfCSP或两者免疫小鼠时，用两种蛋白免疫的小鼠具有比单独用任一种蛋白免疫的小鼠更高的抗PfSPZ的Ab和阻断SPZ在肝细胞中的侵袭和发育的活性（86%）。针对rPfCelTOS的抗体具有针对寄生虫蚊子（动合子）和红细胞前期（SPZ）阶段的生物活性，并且与针对SPZ的抗PfCSP抗体相加或协同的观察结果是独特的，并且为进一步开发这种蛋白质提出了理由。为了进一步增强VIMT效应，我们将评估Pf von Willebrand因子A结构域相关蛋白（PfWARP），这是一种高度保守的可溶性动合子特异性蛋白，我们先前已显示其有效抑制蚊子中肠中卵囊的发育。本研究的目的是开发一种联合多阶段疫苗，通过抑制卵囊发育来有效预防传播。PfCelTOS和PfCSP也在血腔期子孢子中表达，因此我们的策略也将靶向唾液腺中卵囊向感染性子孢子的转化。我们将研究这三种蛋白作为免疫原单独和组合，旨在诱导100%的传输阻断活性。我们相信，消灭疟疾是可以实现的，但没有有效的传播阻断疫苗是不行的，而这三种蛋白质可以实现这一目标。这种疫苗将用于婴儿、幼儿、青春期女性（预防妊娠期疟疾）和消除疟疾运动，作为一项公共卫生措施;这是一个巨大的全球卫生市场。 公共卫生相关性：疟疾每年造成4 - 5亿临床病例和> 100万人死亡，每年造成非洲GDP损失>1%，并且是旅行者和军事人员的严重关切。我们认为，消灭疟疾是可以实现的，但没有有效的阻断传播疫苗就不行。一个合乎逻辑和有前途的战略是联合收割机多阶段目标，以有效地防止传播。这种疫苗将拥有巨大的公共部门市场。在公共部门市场，它将用于婴儿、幼儿、少女（预防妊娠期疟疾）和消除疟疾运动，作为一项公共卫生措施。

DESCRIPTION (provided by applicant): We believe that eradication of malaria is achievable but not without a potent vaccine that interrupt malaria transmission (VIMT) transmission blocking vaccine. A logical and promising strategy is to combine target antigens from multiple stages to potently prevent transmission. To prevent transmission a vaccine should target the pre-erythrocytic (sporozoite and liver stages) and the sexual-mosquito stages of the life cycle. An ideal malaria vaccine would prevent infection, disease, and transmission by targeting at a minimum the pre- erythrocytic (sporozoites and liver stages) and optimally other stages of the parasite life cycle also. Pre- erythrocytic stage vaccine development is based on the observation that immunization via bites of irradiated mosquitoes infected with Plasmodium falciparum (Pf) sporozoites (SPZ) provides high-level protection. The circumsporozoite protein (CSP) was discovered by immunizing mice with irradiated SPZ. A higher percent of volunteers immunized with radiation attenuated PfSPZ have T cells that recognize Pf cell-traversal protein for ookinetes and sporozoites (PfCelTOS) than PfCSP, and immunization of mice with PfCelTOS protects against challenge with rodent malaria SPZ at the pre-erythrocytic stage. We have discovered that antibodies induced in mice by immunizing with recombinant (r) PfCelTOS with adjuvant inhibited Pf development to oocysts in mosquitoes in vivo and PfSPZ invasion and development in hepatocytes in vitro. When mice were immunized with rPfCelTOS alone, rPfCSP alone, or both, mice immunized with both proteins had higher Abs against PfSPZ and activity in blocking SPZ invasion and development in hepatocytes (86%) than did mice immunized with either protein individually. The observations that antibodies against rPfCelTOS, had biological activity against parasite mosquito (ookinete) and pre-erythrocytic (SPZ) stages, and were additive or synergistic with anti-PfCSP antibodies against SPZ are unique, and argue for further development of this protein. To further enhance VIMT effects, we will assess Pf von Willebrand factor A domain-related protein (PfWARP), a highly conserved, soluble ookinete specific protein that we have shown previously to potently inhibit development of oocysts in the mosquito midgut. Our aim in this study is to develop a combined multiple stage vaccine to potently prevent transmission by inhibition of oocyst development. PfCelTOS and PfCSP are also expressed in hemocoel stage sporozoites and thus our strategy would also target the conversion of oocysts to infectious sporozoites in the salivary glands. We will study the three proteins as immunogens alone and in combination, aiming to induce 100% transmission blocking activity. We believe that eradication of malaria is achievable but not without a potent transmission blocking vaccine, and that these 3 proteins can achieve this goal. Such a vaccine would be used in infants, young children, adolescent females (prevent malaria in pregnancy) and malaria elimination campaigns as a public health measure; an enormous global health market. PUBLIC HEALTH RELEVANCE: Malaria causes 400-500 million clinical cases and >1 million deaths annually, is responsible for >1% loss of GDP in Africa annually and is a serious concern for travelers and military personnel. We believe that eradication of malaria is achievable but not without a potent transmission blocking vaccine. A logical and promising strategy is to combine multiple stage targets to potently prevent transmission. Such a vaccine would have huge public-sector markets. In public sector markets it would be used in infants, young children, adolescent females (prevent malaria in pregnancy) and malaria elimination campaigns as a public health measure.