Multi-stage multi-antigen Vaccine for interrupting Malaria Transmission

描述(申请人提供)：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有效疫苗(VIMT传播阻断疫苗)，就不可能实现。一个合理而有希望的策略是将来自多个阶段的靶抗原结合起来，以有效地防止传播。为了防止传播，疫苗应针对生命周期的红细胞前期(子孢子期和肝期)和性蚊子阶段。理想的疟疾疫苗将通过至少针对红细胞前期(子孢子和肝脏阶段)以及最好也针对寄生虫生命周期的其他阶段来预防感染、疾病和传播。红细胞前期疫苗的开发是基于观察到，通过被感染恶性疟原虫(PF)子孢子(SPZ)的受辐射蚊子(SPZ)叮咬进行免疫可提供高水平保护。用辐照过的SPZ免疫小鼠，发现了环子孢子蛋白(CSP)。与PfCSP相比，用辐射减毒的PfSPZ免疫的志愿者拥有识别动子和子孢子的PF细胞穿越蛋白(PfCelTOS)的T细胞比例更高，而PfCelTOS免疫的小鼠在红细胞前期保护免受啮齿动物疟疾SPZ的攻击。我们发现，重组(R)PfCelTOS佐剂免疫小鼠诱导产生的抗体，在体内抑制了蚊虫卵囊的形成，在体外抑制了PfSPZ在肝细胞中的侵袭和发育。当rPfCelTOS、rPfCSP单独免疫或两者联合免疫时，两种蛋白免疫的小鼠的抗PfSPZ抗体和阻断肝细胞SPZ侵袭和发育的活性(86%)均高于单独免疫的小鼠。RPfCelTOS抗体具有抗寄生虫蚊虫(动子)和红细胞前期(SPZ)的生物活性，并与抗SPZ的PfCSP抗体具有相加或协同作用，这一观察结果是独一无二的，为进一步开发该蛋白奠定了基础。为了进一步增强VIMT的作用，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、可溶的运动特异性蛋白，我们之前已经证明它可以有效地抑制蚊子中肠中卵囊的发育。我们在这项研究中的目的是开发一种联合的多阶段疫苗，通过抑制卵囊发育来有效地防止传播。PfCelTOS和PfCSP也在血腔期的子孢子中表达，因此我们的策略也将针对唾液腺中卵囊到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联合使用，目的是诱导100%的传播阻断活性。我们认为，根除疟疾是可以实现的，但如果没有一种有效的传播阻断疫苗，就不可能实现这一目标，这3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(预防孕期疟疾)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。 与公共卫生相关：疟疾每年导致4-5亿临床病例和100万人死亡，每年造成非洲国内生产总值1%的损失，是旅行者和军事人员严重关切的问题。我们认为，根除疟疾是可以实现的，但如果没有一种有效的传播阻断疫苗，就不可能实现。一个合理而有希望的战略是将多个阶段目标结合起来，以有效地防止传播。这样的疫苗将在公共部门拥有巨大的市场。在公共部门市场，它将用于婴儿、幼儿、青春期女性(预防孕期疟疾)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.