DEVELOPMENT OF A RECOMBINANT VACCINE FOR RICIN TOXIN

描述(申请人提供)：蓖麻毒素是已知的最有效的生物毒素之一，过去曾被用作生物武器。自从2003年在几起广为人知的事件中发现并记录了蓖麻毒素的痕迹以来，人们最近一直将注意力集中在实际使用蓖麻毒素的潜在威胁上。目前，没有获得许可的疫苗来预防可能在潜在的恐怖袭击中或在战场上将蓖麻毒素用作武器的气雾剂。这一拟议项目的目的是开发一种肌肉注射的蓖麻毒素疫苗，通过生产过程和中间放大阶段，直到并包括瓶装佐剂配方，用于人类临床研究的最终释放。该项目的团队包括来自行业(DOR生物制药公司)的代表。[dor]和Cambrex Biosciences，Inc.[Camb])、学院(德克萨斯大学西南医学中心[UTSWMC]和堪萨斯大学[英国])和一个非营利性研究机构(斯坦福研究所[SRI])。除了未来的I/II期临床测试外，预计至少数千剂人体剂量的生产目标足以进行稳定性和毒性测试。候选疫苗是一种源自大肠杆菌宿主菌株产生的蓖麻毒素A链的重组多肽。拟议的努力将集中在开发一种先前具有特征的基因失活的蓖麻毒素A链，该链包含导致毒性丧失的位点的非冗余结构突变。执行特定目标所涉及的活动将包括最大限度地提高在大肠杆菌中的表达水平，提高工艺产量，以及开发和验证工艺方法、分析和稳定性指示测试。在制定临床使用的疫苗时，将解决有助于抗原在溶液中稳定的几个因素。此外，开发的批次将在动物模型中进行有效性测试，并解决潜在的毒性问题。开发一种对抗蓖麻毒素中毒的疫苗的一个关键问题将是动物保护反应与人类保护反应之间的相关性，因为在开发过程中不能进行人类挑战/效力研究。根据初步数据，这种特殊的疫苗抗原在特定条件下聚集，可能会影响效力和稳定性。疫苗储存期间多肽结构的保存也将通过制定蛋白质稳定剂接受者的候选疫苗来解决。

DESCRIPTION (provided by applicant): Ricin is one of the most potent biological toxins known and has been used as a biological weapon in the past. Much attention has been recently focused on the potential threat of actual ricin use, since traces of ricin have been found and documented in several well publicized incidents during 2003. Currently, there is no licensed vaccine to protect against the possibility of the aerosol use of ricin in a potential terrorist attack or as a weapon on the battlefield. The purpose of this proposed project is to develop an intramuscularly administered ricin vaccine through process and intermediate scale-up stages of manufacturing, up to and including formulation with adjuvant in vials for final release for human clinical studies. The team for this project includes representatives from industry (DOR Biopharmaceuticals, Inc. [DOR] and Cambrex Biosciences, Inc. [CAMB]), academe (University of Texas Southwestern Medical Center [UTSWMC] and the University of Kansas [UK]) and a non-profit research organization (Stanford Research Institute [SRI]). A production goal of at least several thousand human doses sufficient for stability and toxicity testing, in addition to future Phase I/II clinical testing, is projected. The vaccine candidate is a recombinant polypeptide derived from the A chain of ricin toxin produced in an E. coli host strain. The proposed efforts will focus on the development of a previously characterized genetically inactivated ricin A chain that contains non-redundant structural mutations in sites resulting in loss of toxicity. The activities involved in executing the specific aims will include maximization of expression levels in E. coli, improvement of process yields, and development and validation of process methods, assays, and stability-indicating tests. Several factors that contribute to the stability of the antigen in solution will be addressed in formulating the vaccine for clinical use. Further, the developed lots will be tested in animal models for efficacy and potential toxicity issues will be addressed. A key issue in the development of a vaccine to combat ricin intoxication will be the correlation of animal protective responses with human protective responses, since no human challenge/efficacy studies can be performed during development. Based on preliminary data, this particular vaccine antigen aggregates under certain conditions, potentially affecting potency and stability. Preservation of the polypeptide structure during storage of the vaccine will also be addressed by formulating the vaccine candidate in protein stabilizinq recipients.