Development of a lyophilized intradermal/intranasal ricin vaccine

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核毒素。作为蓖麻油生产的副产品，每年产生5万吨蓖麻毒素。蓖麻毒素在间谍活动和战争中有着悠久的历史，被疾病预防控制中心列为B类生物威胁。目前还没有批准的疫苗。蓖麻毒素A链（RTA）对人类有两种毒性：核糖体失活和血管渗漏综合征。我们之前在两个位点都产生了单个氨基酸变化的重组RTA突变体，并根据高产率和稳定性选择了最佳候选疫苗。这种疫苗（RiVax）被开发成一种冷冻的肌肉注射制剂。Rivax在保护小鼠免受10 ld50的蓖麻毒素侵害方面非常有效。它在兔和人体内都是安全且具有免疫原性的。我们建立了蓖麻毒素灌胃攻击模型，并建立了气溶胶攻击的BSL3实验室。在我们的灌食挑战研究过程中，我们发现蓖麻毒素在灌食时的毒性比以前的文献所建议的要高1000- 10000。由于这一发现，蓖麻毒素对我国平民粮食和水供应的威胁比我们以前认识到的更为严重。因此，对这种疫苗的需求可能比以前认为的更大。因此，我们现在建议开发：1)在环境温度或4℃下稳定的RiVax冻干制剂；2)有效的皮内疫苗接种方案，不需要针头，并且在较低剂量下应具有免疫原性；一种鼻内制剂，可以保护粘膜免受灌胃（和雾化）蓖麻毒素的侵害。4)将对我们的最佳候选配方和方案进行常规毒理学研究。这项研究与公共卫生的相关性（法律语言）：至关重要的是，我们的军队和平民都能获得批准的蓖麻毒素疫苗，以保护他们免受摄入和雾化蓖麻毒素的侵害。这项建议是实现这一目标的关键一步。

DESCRIPTION (provided by applicant): Ricin is a highly lethal ribotoxin produced by castor beans. 50,000 tons of ricin are generated each year as a by product of castor oil production. Ricin has a long history of use in espionage and warfare and is classified by the CDC as a Class B biothreat. There is no approved vaccine. Ricin A chain (RTA) has two toxicities in humans: ribosome inactivation and vascular leak syndrome. We previously generated recombinant RTA mutants with single amino acid changes in both sites, and chose the best candidate vaccine based on high yield and stability. This vaccine (RiVax) was developed into a frozen, intramuscular formulation. Rivax is highly effective in protecting mice against ten LD50s of ricin. It was safe and immunogenic in both rabbits and humans. We developed a gavage challenge model for ricin and set up a BSL3 laboratory for aerosol challenges. During the course of our gavage challenge studies, we found that ricin was 1000-10,000 more toxic when delivered by gavage than the older literature had suggested. As a result of this finding, ricin represents a more serious threat to the food and water supply of our civilian population than we had realized previously. Thus there might be a greater need for this vaccine than previously appreciated. Hence, we now propose to develop: 1) a lyophilized formulation of RiVax that is stable at ambient temperatures or 4¿C; 2) an effective intradermal vaccination regimen that does not require needles and should be immunogenic at lower doses; 3) an intranasal formulation that will protect the mucosa against gavaged (and aerosolized) ricin. 4) Normal toxicology studies will be carried out on our best candidate formulations and regimens. Relevance of this research to public health (lav language): It is critical that both our military and civilian populations have access to an approved ricin vaccine that will protect them against both ingested and aerosolized ricin. This proposal represents a critical step in accomplishing this goal.