Pathogenomics of Chlamydial Infection

研究的重点是了解衣原体多形膜蛋白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。我们已经通过免疫亲和纯化纯化了PmpD的一个天然可溶片段，该片段在感染周期后期分泌到细胞外环境中。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，在蛋白质水平上对纯化的可溶性片段进行鉴定，以确定其二级结构特征。这些研究旨在了解PmpD作为毒力因子在抑制衣原体特异性免疫功能，特别是CD8细胞毒性T细胞免疫中的潜在作用。PmpD在所有沙眼衣原体血清变异株中抗原性高度保守，因此，基于产生广泛交叉反应的保护性抗体反应的亚单位PmpD疫苗是实验室吸引和持续的目标。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，我们正在利用我们的蛋白质结构分析结果来设计能够模拟蛋白质天然结构的重组表达策略。尽管这些研究具有挑战性，但这些研究的成功可能对开发高效的PmpD疫苗至关重要。 通过体内筛选，我们分离到一株超强毒力的沙眼衣原体。这种毒力强的分离物在小鼠的女性生殖道中产生感染和疾病，其病理与人类感染相似。这些发现首次描述了一种对小鼠具有毒力的人类菌株，从而为研究人类感染和疾病提供了一个亟需的小动物模型。值得注意的是，对毒力和无毒克隆菌株的比较基因组学研究显示，只有一个基因发生突变，明确地将该基因(CT153)确定为体内的关键毒力因子。这些发现将加强我们对人类疾病病理生理学的理解，并在细胞水平上更好地确定对发展对感染的保护性免疫至关重要的免疫机制。未来的研究将集中在了解CT135是如何加剧感染的，以及CT135突变是否与人类疾病中衣原体的毒力有关。明确CT135在发病机制中的作用可以为衣原体疫苗的设计和开发提供新的见解。

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.