Development of a whole parasite Plasmodium falciparum sexual and mosquito stages Vaccine to Interrupt Malaria Transmission

 描述（由申请方提供）：本提案将证明针对恶性疟原虫（Pf）性期和蚊期（SMS）的全寄生虫（WP）疫苗的概念验证，该疫苗将单独使用或与PfSPZ疫苗联合使用，以阻断疟疾从人类宿主传播至蚊媒（VIMT）。这样的PfSMS-WP-VIMT将是PfSPZ疫苗的理想补充，PfSPZ疫苗在最近的临床试验中显示出对寄生虫感染的完全保护作用。如果PfSPZ疫苗在90%的接受者中预防感染和传播，PfSMS-WP-VIMT在90%的接受者中预防传播，则该组合将在至少99%的接受者中预防传播。PfSMS-WP-VIMT为基于一种或几种抗原的亚单位PfSMS疫苗提供了主要优势。这种疫苗方法将增加更多个体具有保护性免疫应答的机会，并通过显著增加诱导保护性抗体的免疫原的数量来降低寄生虫能够选择逃避免疫应答的可能性。当与PfSPZ疫苗联合使用时，PfSMS-WP-VIMT将防止可能对PfSPZ疫苗产生耐药性的寄生虫的传播。Sanaria独特地在GMP条件下产生Pf配子母细胞（有性阶段），现在在体外持续产生配子、合子和动合子的混合物，富集动合子。我们部分纯化了这些寄生虫，用佐剂中的制剂免疫小鼠，并表明免疫小鼠的血清完全（100%）抑制寄生虫向蚊子的传播。我们将利用Sanaria在符合GMP的配子体生产和体外PfSPZ生产方面的独特专业知识，以及在寄生虫纯化和体内传播阻断喂养试验方面的丰富经验，开发，生产和测试PfSMS-WP- VIMT。我们将从三个时间点（30-60 min、8 h和30 h）生产PfSMS培养物，以确保存在所有PfSMS阶段。我们将纯化这些培养物中的PfSMS，使其远离RBC，以获得纯化的疫苗制剂。概念验证将通过用PfSMS-WP制剂与佐剂组合免疫小鼠，然后测试针对培养的寄生虫和已知PfSMS抗原的抗体应答，以及在体内标准膜饲养测定中测试传播阻断活性来证明。通过直接静脉接种（DVI）联合给药后，将在小鼠中进一步检测先导候选疫苗与PfSPZ疫苗的相互作用。在第二阶段，我们将最终确定符合cGMP和质量控制（QC）放行和稳定性试验的规模化生产方法，按照cGMP进行生产，进行QC放行试验，启动QC稳定性研究，进行临床前毒理学研究，设计临床试验，并为新药研究申请（IND）准备所有信息。

 DESCRIPTION (provided by applicant): This proposal will demonstrate proof of concept for a whole parasite (WP) vaccine directed against Plasmodium falciparum (Pf) sexual and mosquito stages (SMS) that will be used alone or in combination with PfSPZ Vaccine for interrupting malaria transmission (VIMT) from the human host to the mosquito vector. Such a PfSMS-WP-VIMT will be an ideal complement to the PfSPZ Vaccine, which has shown complete protection against parasite infection in recent clinical trials. If the PfSPZ Vaccine prevents infection and transmission in 90% of recipients and PfSMS-WP-VIMT prevents transmission in 90% of recipients, the combination will prevent transmission in at least 99% of recipients. The PfSMS-WP-VIMT offers major advantages to a subunit PfSMS vaccine based on one or a few antigens. This vaccine approach will increase the chance that more individuals will have protective immune responses and reduce the possibility of the parasites being able to select for evasion of immune responses by dramatically increasing the number of immunogens against which protective antibodies are induced. When used in combination with PfSPZ Vaccine, PfSMS-WP-VIMT will prevent transmission of parasites that may be selected for resistance to PfSPZ Vaccine. Sanaria uniquely produces Pf gametocytes (sexual stages) under GMP conditions and now consistently produces a mixture of gametes, zygotes and ookinetes, enriched for ookinetes, in vitro. We partially purified these parasites, immunized mice with the preparation in adjuvant, and showed that the sera from the immunized mice completely (100%) inhibited transmission of parasites to mosquitoes. We will exploit Sanaria's unique expertise in GMP-compliant gametocyte production and in vitro PfSPZ production, as well as extensive experience in parasite purification and in vivo transmission blocking feeding assays to develop, produce and test PfSMS-WP- VIMT. We will produce cultures of PfSMS from three time points (30-60 min, 8 h and 30 h) to ensure that all PfSMS stages are present. We will purify PfSMS in these cultures away from RBCs to obtain purified vaccine preparations. Proof of concept will be demonstrated by immunizing mice with the PfSMS-WP preparations in combination with adjuvants, then testing for antibody responses against cultured parasites and known PfSMS antigens, and for transmission blocking activity in an in vivo standard membrane feeding assay. The lead candidates will be further tested in mice for interactions with the PfSPZ Vaccine after co-administration by direct venous inoculation (DVI). In Phase II we will finalize methods for scaled-up manufacturing in compliance with cGMPs and quality control (QC) release and stability assays, manufacture in compliance with cGMPs, conduct QC release assays, initiate QC stability studies, conduct pre-clinical toxicology studies, design a clinical trial, and prepare al information for an Investigational New Drug application (IND).