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

描述（由申请人提供）：鼠疫耶尔森氏菌是最著名的鼠疫病原体，鼠疫是一种由受感染跳蚤叮咬传播的疾病。然而，如果吸入，这种病原体也会产生称为肺鼠疫的严重原发性肺炎，这种疾病既具有传染性，又具有高度致命性。虽然一种由鼠疫杆菌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，但在灵长类动物中有效的肺鼠疫疫苗仍然难以捉摸。此外，缺乏F1的鼠疫耶尔森氏菌菌株保留了引起肺鼠疫的能力，这可能会由于F1/LcrV疫苗接种个体中自发或工程化的F1表达缺失而破坏保护。包括我们自己在内的几个小组的实验数据表明，pH 6抗原（Psa菌膜）在体内在细胞外细菌上表达。我们最近观察到，在小鼠肺部感染实验中，Psa疫苗对一种减毒鼠疫杆菌菌株具有显著的保护作用。本研究的第一个目的是通过用完全毒力菌株KIM1001和CO92攻击小鼠，进一步验证Psa的保护特性。铁处理小鼠模型与减毒pgm株KIM5的价值将在平行实验中进行研究。在体外将建立抗体和T细胞介导的保护的相关性。由于我们已经证明，Psa蛋白抗原诱导强烈的体液反应，将评估通过抗体从接种疫苗的小鼠转移到幼稚小鼠的被动保护。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描述Psa在鼠疫致病性中的作用。我们已经证明，Psa菌毛是多聚黏附素，通过与磷脂酰胆碱的胆碱部分的高亲和性相互作用，以及与糖脂的21链半乳糖残基的低亲和性相互作用，介导鼠疫菌与人呼吸道上皮细胞的结合。正如我们（和其他人）已经证明Psa加速鼠疫杆菌在受感染宿主中的传播，我们将评估Psa介导的粘附是否有助于这种反应。位点导向的Psa固定突变体不能与胆碱或/和21-连接半乳糖结合，它们的传播特性将在小鼠中进行研究。获得的结果将指导设计能够阻断psa介导的细菌粘附的聚合物抑制剂。确定延缓细菌在体内传播的抑制剂将支持未来粘附抑制剂作为抗毒疗法的发展。我们的第一个目标是确定Psa是否可以作为一种有价值的免疫原添加到目前的实验性F1-LcrV疫苗中，以提供更广泛的预防鼠疫，特别是肺炎形式的保护。我们的第二个目标是确定psa介导的粘附是否有助于毒力，以及设计用于阻断psa介导的粘附的治疗方法是否可以延迟疾病进展，从而提高抗生素治疗的成功率。公共卫生相关性：本提案的第一个目标是确定使用鼠疫耶尔森菌表面结构，Psa菌膜，作为一种保护鼠疫的免疫原。第二个目标是表征Psa抑制剂的使用，Psa通过支持宿主的细菌定植和疾病进展而作为毒力因子。这些研究的结果将为未来开发支持传统抗生素治疗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.