Pathogenomics of Chlamydial Infection

研究的重点是了解衣原体多态膜蛋白D （PmpD）的结构和功能，以更好地确定其在衣原体感染生物学中的作用及其与宿主免疫系统的相互作用。我们通过免疫亲和纯化纯化了PmpD的天然可溶性片段，该片段在感染周期后期分泌到细胞外环境中。纯化的可溶性片段在蛋白质水平上进行表征，以确定其二级结构特征，并通过研究天然蛋白与培养的真核细胞、人T细胞和树突状细胞的相互作用进行生物学研究。这些研究旨在了解PmpD作为毒力因子可能在抑制衣原体特异性免疫功能中的潜在作用；特别是CD8细胞毒性T细胞免疫在所有沙眼衣原体血清变体中，PmpD的抗原性是高度保守的，因此基于产生广泛交叉反应性保护性抗体应答的亚基PmpD疫苗是实验室一个有吸引力的和持续的目标。由于PmpD的构象对其产生高效保护性中和抗体的能力至关重要，我们正在利用蛋白质结构分析的发现来设计能够模仿蛋白质天然结构的重组表达策略。尽管具有挑战性，但这些研究的成功可能对开发有效的基于PmpD的疫苗至关重要。

Studies are focused on understanding the structure and function of the chlamydial polymorphic membrane protein D (PmpD) to better define its role in the biology of chlamydial infection and in its interaction with the host immune system. We have purified to homogeneity by immunoaffinity purification a native soluble fragment of PmpD that is secreted into the extracellular environment late in the infection cycle. The purified soluble fragment is being characterized at the protein level to define its secondary structural characteristics, and biologically by studying the interaction of the native protein with culture eukaryotic cells, human T cells, and dendritic cells. These studies are aimed at understanding the potential role of PmpD as virulence factor that might function in the suppression of chlamydial specific immune functions; specifically CD8 cytotoxic T cell immunity. PmpD is highly conserved antigenically among all C. trachomatis serovariants therefore a subunit PmpD vaccine based on the generation of a broadly cross-reactive protective antibody response is an attractive and ongoing goal of the laboratory. As the conformation of PmpD is essential for its ability to generate highly efficacious protective neutralizing antibodies we are using our protein structural analysis findings to design recombinant expression strategies capable of mimicking the proteins native structure. Although challenging, the success of these investigations are likely critical to the development of an efficious PmpD based vaccine. Using in vivo selection we isolated a hypervirulent C. trachomatis human urogential strain. The virulent isolate produces infection and disease in the mouse female genital tract with similar pathology to that of human infection. These findings are the first description of a human strain that is virulent for the mouse thereby providing a much needed small animal model for the study of human infection and disease. Remarkably, comparative genomic studies of virulent and avirulent clonal strains revealed a mutation in only a single gene unambiguously identifying the gene (CT153) as a critical in vivo virulence factor. These findings will enhance our understanding of the pathophysiology of human disease and better define at the cellular level immune mechanisms important to the devopment of protective immunity to infection. Future studies will focus on understanding how CT135 exacerbates infection and whether CT135 mutations are associated with chlamydial virulence in human disease. Defining the role of CT135 in pathogenesis could provide new insights important to chlamydial vaccine design and development.