A Novel Recombinant Protein Vaccine Against Ricin Toxin

描述（由申请人提供）：蓖麻毒素是一种由蓖麻产生的高致命性毒素。它很容易获得，易于制作和储存。蓖麻毒素在间谍活动和战争中有着悠久的使用历史，记录在案的中毒案例有750例。蓖麻毒素被疾控中心列为B类生物威胁。在20世纪90年代，美国军方在获得恐怖组织储存蓖麻毒素的信息后，对开发一种针对蓖麻毒素的疫苗产生了兴趣。一种蓖麻毒素类毒素对灵长类动物有保护作用，但毒性很大，没有得到FDA的批准。我们制备了三个蓖麻毒素A链的重组突变体，它们在小鼠中既没有血管泄漏活性，也没有酶活性。注射后，这些突变体保护小鼠免受大剂量注射蓖麻毒素的侵害。我们的目标是将其中一种突变体开发成一种廉价、安全、有效、稳定和“用户友好”的疫苗，可用于大量人群。本建议的具体目的是：1)优化疫苗的生产、纯化、配方和稳定性。2)确定疫苗是否能保护小鼠免受雾化和腹腔（i.p）蓖麻毒素攻击，如果是，最佳免疫方法（i.m，口服或鼻内），以最长时间保护动物。3)生产一小批最佳候选疫苗，并使用最佳给药途径对6只成年狒狒（3只雄性和3只雌性）进行免疫。当这三个目标完成后，该疫苗应准备好在两个物种中进行急性毒理学研究，并扩大规模进行人体第一阶段临床试验。

DESCRIPTION (provided by applicant): Ricin is a highly lethal toxin produced by castor beans. It is readily available, easy to make, and stockpile. Ricin has a long history of use in espionage and warfare with a documented 750 cases of intoxication. Ricin is classified by the CDC as a Class B biothreat. In the 1990s, the U.S. Military became interested in developing a vaccine against ricin after obtaining information that this toxin was being stockpiled by terrorist organizations. A ricin toxoid is protective in primates, but it is quite toxic and did not receive FDA approval. We have generated three recombinant mutants of ricin's A chain which are devoid of both vascular leak activity and enzymatic activity in mice. When injected i.m., these mutants protect mice against very large doses of injected ricin. Our goal is to develop one of these mutants into an inexpensive, safe, effective, stable, and "user-friendly" vaccine which can be administered to large groups of people. The specific Aims of this proposal are: 1) to optimize production, purification, formulation and stability of the vaccine. 2) to determine whether the vaccine will protect mice against aerosolized as well as intraperitoneal (i.p.) ricin challenge and if so, the best method of immunization (i.m., oral, or intranasal) to protect animals for the longest period of time and 3) to produce a small good laboratory practice (GLP) batch of the best candidate vaccine and use the best route of administration to immunize six adult baboons (three males and three females). When these three aims are completed, the vaccine should be ready for acute toxicology studies in two species and scale-up for Phase 1 clinical trials in humans.