Development of a lyophilized intradermal/intranasal ricin vaccine

描述(申请人提供)：蓖麻毒素是一种由蓖麻籽产生的高度致命的核毒素。每年产生5万吨蓖麻毒素，作为生产蓖麻油的副产品。蓖麻毒素在间谍和战争中的使用历史悠久，被美国疾病控制与预防中心列为B类生物制剂。目前还没有批准的疫苗。蓖麻毒素A链(RTA)对人体有两种毒性作用：核糖体失活和血管渗漏综合征。我们先前构建了两个位点都有单一氨基酸变化的重组RTA突变体，并在高产和稳定的基础上选择了最好的候选疫苗。这种疫苗(RiVax)被开发成一种冷冻的肌肉内制剂。RiVax可以非常有效地保护小鼠免受10种LD50的蓖麻毒素的伤害。它对兔和人都是安全的和免疫原性的。我们开发了蓖麻毒素的灌胃挑战模型，并建立了气溶胶挑战的BSL3实验室。在我们对灌胃挑战进行研究的过程中，我们发现，通过灌胃给药时，蓖麻毒素的毒性比旧文献所建议的要高1000-10000。这一发现的结果是，蓖麻毒素对我国平民人口的食物和水供应构成比我们以前认识到的更严重的威胁。因此，对这种疫苗的需求可能比之前估计的更大。因此，我们现在建议开发：1)在常温或4℃下稳定的RiVax冻干制剂；2)不需要针头且在较低剂量下具有免疫原性的有效皮内疫苗接种方案；3)保护粘膜免受灌胃(和雾化)蓖麻毒素的鼻内制剂。4)我们将对我们的最佳候选配方和方案进行正常的毒理学研究。这项研究与公共卫生的相关性(LAV语言)：至关重要的是，我们的军人和平民都能获得经批准的蓖麻毒素疫苗，该疫苗将保护他们免受摄入和雾化的蓖麻毒素的伤害。这项提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.