Function and immunogenicity of Yersinia pestis fimbriae

描述(申请人提供)：鼠疫耶尔森氏菌是鼠疫的病原体。被雾化的鼠疫杆菌被认为是最危险的生物武器。目前还没有疫苗保护人类免受肺炎鼠疫的侵袭，肺炎鼠疫是最具传染性和致命性的鼠疫形式。该项目的长期目标是开发一种新的、具有成本效益的疫苗，能够诱导粘膜和系统免疫，以延长对鼠疫的保护。所研究的鼠疫杆菌主要原型疫苗只基于两个亚单位抗原，其中一个不是毒力所必需的。这样的疫苗可能无法保护足够广泛的具有不同遗传背景的个人。它们还面临着对自然选择的或工程改造的鼠疫变种变得无效的风险。最近破译的鼠疫耶尔森氏菌基因组将用于研究其他免疫原性蛋白靶点，最好是参与鼠疫耶尔森氏菌致病机制的某些方面。在包括鼠疫耶尔森氏菌在内的大多数肠杆菌科细菌中发现的菌毛蛋白都具有这种特性。菌毛是以毛状细胞器形式聚集在细菌表面的聚合体蛋白。除了是研究最充分和最有效的细菌免疫原外，许多菌毛还直接参与介导细菌与宿主粘膜表面的结合。菌毛通常能诱导高滴度的抗细菌和抗粘连抗体。它们可以通过简单的方法大量分离，使它们成为具有成本效益的疫苗。该项目的第一个目标是克隆每个已鉴定的菌毛基因簇，并在大肠杆菌表面表达菌毛。其次，我们将确定这些菌毛中是否有任何一种参与了大肠杆菌与相关的上皮细胞或先天免疫系统细胞的结合。第三，菌毛在体内的表达将通过筛选受挑战的小鼠的抗体来确定。菌毛在发病机制中的重要性将通过突变体进行研究。第四，将用菌毛对小鼠进行非肠道免疫，并通过口服或鼻腔接种表达鼠疫菌毛的减毒沙门氏菌疫苗株。将研究全身和粘膜的体液免疫反应以及抗黏附抗体的诱导。将进行挑战性实验，以研究这些疫苗的免疫保护作用。

DESCRIPTION (provided by applicant): Yersinia pestis is the causative agent of Plague. Aerosolized Y. pestis is feared as a most dangerous bioweapon. There is currently no vaccine protecting humans against pneumonic Plague, the most contagious and lethal form of Plague. The long-term goal of this project is to develop a new, cost-effective vaccine capable of inducing mucosal and systemic immunity for extended protection against Plague. The studied major prototype vaccines against Y. pestis are based on only two subunit antigens, one not required for virulence. Such vaccines might not protect a sufficiently broad population of individuals with different genetic backgrounds. They also run the risk of becoming ineffective against naturally selected or engineered mutants of Y. pestis. The recently deciphered Y. pestis genome will be used to study additional immunogenic protein targets, preferably involved in some aspects of Y. pestis pathogenesis. The fimbrial proteins found in most if not all Enterobacteriaceae, including Y. pestis, are bestowed with such properties. Fimbriae are polymeric proteins assembled as hair-like organelles on bacterial surfaces. In addition to being among the best studied and most effective bacterial immunogens, many fimbriae are directly involved in mediating bacterial binding to host mucosal surfaces. Fimbriae induce typically high titers of both anti-bacterial and antiadhesive antibodies. They can be isolated in large amounts by simple methods, making them cost-effective vaccines. The first aim of this project is to clone each of the identified fimbrial gene clusters and to express the fimbriae on the surface of E. coli. Second, we will determine whether any of these fimbriae mediate E. coil binding to relevant epithelial cells or cells of the innate immune system. Third, in vivo expression of fimbriae will be determined by screening for antibodies in challenged mice. The importance of the fimbriae in pathogenesis will be studied with mutants. Fourth, mice will be immunized parenterally with fimbriae, and either orally or intra-nasally with an attenuated Salmonella vaccine strain expressing Y. pestis fimbriae. Systemic and mucosal humoral immune responses and the elicitation of anti-adhesive antibodies will be investigated. Challenge experiments will be undertaken to study immuno-protection by these vaccines.