IMMUNOPATHOGENESIS OF CRYPTOSPORIDIOSIS

T细胞和B细胞介导的免疫被认为在根除和保护隐孢子虫感染中发挥作用，但人类宿主防御的特定成分介导成功免疫的机制尚不清楚。虽然已经鉴定出许多隐孢子虫蛋白，但它们的功能和意义尚不清楚。隐孢子虫与其靶宿主细胞--肠道上皮细胞的相互作用以及寄生虫蛋白在这种相互作用中的作用也鲜有研究。在拟议的研究中，我们将把十多年的临床试验工作中获得的经验和生物样本带到试验台上，以开始揭开隐孢子虫通过与肠道上皮细胞相互作用而触发免疫反应的机制。在我们对艾滋病慢性隐孢子虫病患者系列血清样本的初步分析中，我们发现感染的完全临床和寄生虫学消退与活跃的体液免疫反应相一致，特别是针对33kD隐孢子虫蛋白(p-33)的免疫球蛋白的产生。本项目的重点是研究p-33的特性及其作为毒力因子的潜在作用。此外，这些研究为研究隐孢子虫感染的免疫功能提供了一种新的途径，因为它们将集中在p-33作为T细胞抗原的潜在作用上。我们的具体目标是：(1)鉴定33kD的隐孢子虫蛋白；(2)探索p-33作为T细胞依赖抗原的潜在作用。由于与目标2相关的工作没有模型，我们采用了一种创新的方法来开发有用的模型，以研究对隐孢子虫的肠道免疫。

Both T- and B-cell mediated immunity are believed to play a role in the eradication of and protection from cryptosporidial infections but the mechanisms by which specific components of human host defense mediate successful immunity are unknown. Although many cryptosporidial proteins have been identified, neither their function nor their significance is known. The interaction of Cryptosporidium with its target host cell, the intestinal epithelial cell, and the role of parasite proteins in this interaction has also been little studied. In the proposed studies we will bring the experience and biological samples obtained in over ten years of clinical trials work to the bench in order to begin to unravel the mechanisms by which Cryptosporidium triggers an immune response by virtue of its interaction with the intestinal epithealial cell. In our preliminary analysis of serial serum samples from AIDS patients with chronic cryptosporidiosis, we found that complete clinical and parasitologic resolution of infection coincides with a brisk humoral immune response, and specifically with generation of immunoglobulin directed against a 33 kD cryptosporidial protein (p-33). This project focuses on characterization of p-33 and investigation of its potential role as a virulence factor. Furthermore, the proposed studies provide a novel approach to the study of immune function in cryptosporidial infection because they will focus on the potential role of p-33 as a T-cell antigen. Our specific aims are to: (1) characterize the 33 kD cryptosporidial protein, and (2) explore the potential role of p- 33 as a T-cell dependent antigen. As there are no models in place for work related to Aim 2, we have adopted an innovative approach for developing useful models for the study of intestinal immunity against Cryptosporidium.