The Psa fimbriae of Yersinia pestis, an adhesin with protective immunogenic prope

描述(申请人提供)：鼠疫耶尔森氏菌是众所周知的腺鼠疫的病原体，腺鼠疫是一种通过受感染的跳蚤叮咬传播的疾病。然而，如果吸入这种病原体，还会产生一种被称为肺鼠疫的严重的原发肺炎，这种肺炎既有传染性，又具有高度致命性。尽管由鼠疫F1和LcrV蛋白组成的实验性疫苗在小鼠模型中取得了令人鼓舞的结果，但针对灵长类动物肺炎鼠疫的有效疫苗仍然难以找到。此外，F1缺陷鼠疫菌株仍具有引起肺鼠疫的能力，允许在接种F1/LcrV疫苗的个体中由于自发或人为地丧失F1表达而潜在地破坏保护。包括我们自己在内的几个小组的实验数据表明，在活体内胞外细菌上表达了pH 6抗原(PSA菌毛)。我们最近在小鼠肺部感染实验中观察到，接种PSA疫苗对减毒的鼠疫菌株具有显著的保护作用。本研究的第一个目的是通过用全毒力株KIM1001和CO92攻击小鼠来进一步验证PSA的保护特性。铁处理的小鼠模型与PGM减毒株KIM5一起使用的价值将在平行实验中进行调查。在体外，抗体和T细胞介导的保护之间的相关性将被建立。由于我们已经证明PSA蛋白抗原诱导了强烈的体液反应，因此将评估从接种疫苗的小鼠向未接种的小鼠转移抗体的被动保护作用。T细胞介导的保护作用将通过免疫和T细胞转移实验在B细胞缺陷小鼠中进行评估。我们的第二个目标是确定PSA在鼠疫致病中的作用。我们已经证明PSA菌毛是多聚体粘附素，通过与磷脂酰胆碱的胆碱部分具有高亲和力，而对糖脂的21-连接的半乳糖残基具有较低的亲和力，介导鼠疫菌与人呼吸道上皮细胞的结合。由于我们(和其他人)已经证明了PSA加速了鼠疫杆菌在受感染宿主中的传播，我们将评估PSA介导的黏附是否有助于这种反应。不能与胆碱或/和21-半乳糖基结合的定点定向PSA菌毛突变体将被设计出来，并将在小鼠身上研究它们的传播特性。所得结果将指导设计能够阻断PSA介导的细菌黏附的聚合物抑制剂。寻找延缓细菌在体内扩散的抑制剂将支持黏附抑制剂作为抗毒力治疗药物的未来发展。我们的第一个目标是确定PSA是否会成为一种有价值的免疫原，可以添加到目前正在试验的F1-LcrV疫苗中，以提供对鼠疫，特别是肺炎形式的更广泛的保护。我们的第二个目标是确定PSA介导的黏附是否有助于毒力，以及旨在阻断PSA介导的黏附的治疗方法的开发是否可以延缓疾病的进展，从而提高抗生素治疗的成功率。公共卫生相关性：该提案的第一个目标是确定使用鼠疫耶尔森氏菌表面结构PSA菌毛作为预防鼠疫的保护性免疫原。第二个目标是描述PSA抑制剂的用途，PSA通过支持宿主的细菌定植和疾病进展而充当毒力因子。这些研究结果将为未来开发支持传统抗生素疗法的疫苗和药物提供有用的基础。

DESCRIPTION (provided by applicant): Yersinia pestis is best known as the causative agent of bubonic plague, a disease transmitted by the bite of infected fleas. However, if inhaled, this pathogen also produces a severe primary pneumonia known as pneumonic plague, which is both contagious and highly lethal. Although an experimental vaccine that consists of Y. pestis F1 and LcrV proteins has given encouraging results in murine models, an efficient vaccine against pneumonic plague in primates remains elusive. Moreover, F1-deficient strains of Y. pestis retain the ability to cause pneumonic plague, allowing for the potential breakdown of protection due to spontaneous or engineered loss of F1 expression in F1/LcrV vaccinated individuals. Experimental data from several groups, including our own, indicates that the pH 6 antigen (Psa fimbriae) is expressed on extracellular bacteria in vivo. We recently observed that vaccination with Psa affords significant protection against an attenuated Y. pestis strain in pulmonary infection experiments in mice. The first aim of this study is to further verify the protective properties of Psa by challenging mice with the fully virulent strains KIM1001 and CO92. The value of an iron-treated mouse model for use with the attenuated pgm strain KIM5 will be investigated in parallel experiments. In vitro correlates of antibody- and T cell-mediated protection will be established. As we have shown that the Psa protein antigen induces a strong humoral response, passive protection by antibody transfer from vaccinated to naive mice will be evaluated. The involvement of T cell-mediated protection will be evaluated in B-cell deficient mice by immunization and T cell transfer experiments. Our second aim is to characterize the role of Psa in plague pathogenicity. We have shown that the Psa fimbriae are multimeric adhesins that mediate Y. pestis binding to human respiratory tract epithelial cells by interacting with high avidity to choline moieties of phosphatidylcholine, and with lower avidity to 21-linked galactosyl residues of glycolipids. As we (and others) have demonstrated that Psa accelerates Y. pestis dissemination in infected hosts, we shall evaluate whether Psa-mediated adhesion contributes to this response. Site-directed Psa fimbriated mutants unable to bind to choline or/and 21-linked galactosyl will be engineered and their disseminating properties will be investigated in mice. The results obtained will guide the design of polymeric inhibitors capable of blocking Psa-mediated bacterial adhesion. Identifying inhibitors that delay bacterial dissemination in vivo will support future development of adhesion inhibitors as anti-virulence therapeutics. The goal of our first aim is to determine if Psa would be a valuable immunogen to add to the current experimental F1-LcrV vaccine to offer a broader protection against plague and particularly the pneumonic form. The goal of our second aim is to determine if Psa-mediated adhesion contributes to virulence and if development of therapeutics designed to block Psa-mediated adhesion could delay disease progression, thereby improving the success of antibiotic treatments. PUBLIC HEALTH RELEVANCE: This proposal's first goal is to determine the use of a Yersinia pestis surface structure, the Psa fimbriae, as a protective immunogen against plague. A second goal is to characterize the use of inhibitors of Psa, Psa acting as a virulence factor by supporting bacterial colonization of the host and disease progression. The result of these studies will provide a useful basis for future development of vaccines and drugs that support traditional antibiotic therapy.