Vaccination with purified, cryopreserved, infectious Plasmodium vivax sporozoites

描述（由申请人提供）：间日疟原虫（Pv）是第二大人类疟疾寄生虫，每年造成超过8000万例病例。然而，预防和控制Pv疟疾的努力面临着耐药性和休眠形式反复复发的重大挑战。此外，由于Pv寄生虫不能在连续的体外培养中生长，因此Pv疫苗的开发受到阻碍。Sanaria已经制造了世界上唯一的纯化的、冷冻保存的、小瓶化的间日疟原虫（Pv）子孢子（SPZ），并且显示这些冷冻保存的PvSPZ可以用于感染黑猩猩和体外感染肝细胞，Sanaria现在准备使用这些感染性PvSPZ作为针对Pv的第一个完整寄生虫疫苗。该战略利用了仅有的两种方法之一的成功，这两种方法曾经在人类中诱导针对Pf疟疾的持久免疫力，一种使用放射减毒，另一种使用非减毒的完全感染性SPZ与氯喹。在一篇开创性的论文中显示，通过携带完全感染性恶性疟原虫子孢子（PfSPZ）的蚊子叮咬服用氯喹的志愿者进行免疫接种诱导了100%的保护性免疫，并且在最后一次免疫接种后28个月仍然存在保护作用。Sanaria独特的技术平台允许通过生产冷冻保存的感染性PfSPZ（PfSPZ攻毒）立即转化这一观察结果，当通过针头和注射器向人类给药时，PfSPZ具有完全感染性，并且涉及感染性PfSPZ与氯喹（PfSPZ CVac）的试验预计将于2012年在美国和欧洲开始开始。进行PvSPZ-CVac的临床试验将需要投资开发PvSPZ的独特GMP生产。在投资此类开发之前，在动物模型中获得PvSPZ-CVac的概念验证数据将是有用的。这只能在非人灵长类动物中进行，因为PvSPZ不会感染任何其他动物。因此，在生产用于临床试验的符合cGMP的材料之前，我们建议评估PvSPZ-CVac在玻利维亚赛米里猴中的保护效力。我们将首先确定冻存PvSPZ的最小感染剂量，随后进行免疫原性和保护效力研究。所产生的数据将一起提供对我们的冷冻保存的PvSPZ的体内感染性、PvSPZ-CVac的保护功效以及保护的免疫机制的深入了解。它们将潜在地提供可用于人类的保护的免疫相关性，并为人类PvSPZ疫苗的免疫方案的更好设计提供信息。 公共卫生相关性：间日疟原虫（Pv）是第二大人类疟疾寄生虫，每年造成超过8000万例病例。然而，预防和控制Pv疟疾的努力面临着耐药性和休眠形式反复复发的重大挑战。此外，由于Pv寄生虫不能在连续的体外培养中生长，因此Pv疫苗的开发受到阻碍。在制造了世界上唯一一种纯化的、冷冻保存的、瓶装的间日疟原虫（Pv）SPZ，并证明这些冷冻保存的PvSPZ可用于感染黑猩猩和体外感染肝细胞后，Sanaria现在准备使用这些传染性PvSPZ作为有史以来第一个用氯喹预防的抗Pv的完整寄生虫疫苗。在生产符合cGMP的临床试验材料之前，我们建议在非人灵长类动物中建立PvSPZ-氯喹模型的原理证明，其特定目的是首先确定玻利维亚赛米里猴中冻存PvSPZ的最小感染剂量，随后进行免疫原性和保护效力研究，所有这些研究预计将为后续的首次全PvSPZ疫苗临床试验提供信息。

DESCRIPTION (provided by applicant): Plasmodium vivax (Pv) is the 2nd most important human malaria parasite, causing > 80 million cases annually. However, efforts to prevent and control Pv malaria face major challenges of drug resistance and repeated relapses from dormant forms. Moreover, Pv vaccine development has been impeded, because Pv parasites cannot be grown in continuous in vitro culture. Having manufactured the only purified, cryopreserved, vialed P. vivax (Pv) sporozoites (SPZ) in the world, and showed that these cryopreserved PvSPZ can be used to infect a chimpanzee and to infect hepatocytes in vitro, Sanaria is now poised to use these infectious PvSPZ as a first- ever whole parasite vaccine against Pv. The strategy capitalizes on the success of one of only two approaches that have ever induced long-lasting immunity against Pf malaria in humans, one using radiation-attenuated and the other using non-attenuated fully infectious SPZ with chloroquine. In a seminal paper it was shown that immunization by the bite of mosquitoes carrying fully infectious Plasmodium falciparum sporozoites (PfSPZ) of volunteers taking chloroquine induced 100% protective immunity, and protection was still present at 28 months after last immunization. Sanaria's unique technology platform has allowed an immediate translation of this observation with the manufacture of cryopreserved infectious PfSPZ (PfSPZ Challenge) that are fully infectious when administered by needle and syringe to humans, and trials involving infectious PfSPZ with chloroquine (PfSPZ CVac) are expected to begin in the U.S. and Europe in 2012. Conducting clinical trials of PvSPZ-CVac will require investment in development of a unique GMP manufacturing for PvSPZ. Prior to investing in such development, it would be useful to obtain proof of concept data for PvSPZ-CVac in an animal model. This can only be done in non-human primates, as PvSPZ do not infect any other animals. Therefore, before manufacturing cGMP-compliant material for clinical trials, we propose to assess the protective efficacy in Saimiri boliviensis monkeys of PvSPZ-CVac. We will first establish a minimum infective dose for cryopreserved PvSPZ and subsequently carry out immunogenicity and protective efficacy studies. Together the data generated will provide insight into the in vivo infectivity of our cryopreserved PvSPZ, the protective efficacy of PvSPZ-CVac, and the immune mechanisms of protection. They will potentially provide an immune correlate of protection that can be used in humans, and inform better design of an immunization regimen for a PvSPZ vaccine for humans. PUBLIC HEALTH RELEVANCE: Plasmodium vivax (Pv) is the 2nd most important human malaria parasite, causing > 80 million cases annually. However, efforts to prevent and control Pv malaria face major challenges of drug resistance and repeated relapses from dormant forms. Moreover, Pv vaccine development has been impeded, because Pv parasites cannot be grown in continuous in vitro culture. Having manufactured the only purified, cryopreserved, vialed P. vivax (Pv) SPZ in the world, and showing that these cryopreserved PvSPZ can be used to infect a chimpanzee and to infect hepatocytes in vitro Sanaria is now poised to use these infectious PvSPZ as a first-ever whole parasite vaccine against Pv given with chloroquine prophylaxis. Before manufacturing cGMP-compliant material for clinical trials, we propose to establish proof of principle for the PvSPZ-chloroquine model in non- human primates under specific aims designed to first establish a minimum infective dose for cryopreserved PvSPZ in Saimiri boliviensis monkeys, and subsequently carry out immunogenicity and protective efficacy studies all of which are expected to inform the subsequent first clinical trials of a whole PvSPZ vaccine.