The Characterization Of P. carinii Surface Antigens

卡氏疟原虫表面抗原的表征

• 批准号: 6993770
• 负责人: JOSEPH A KOVACS
• 金额: --
• 依托单位: CLINICAL CENTER
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6993770
• 关键词: HIV infections; Pneumocystis carinii; Pneumocystis pneumonia; chemical structure function; clinical research; communicable disease transmission; enzyme linked immunosorbent assay; fungal genetics; fungal proteins; gene expression; genetic library; genetic mapping; glycoproteins; host organism interaction; human tissue; immune response; laboratory rat; microorganism immunology; molecular cloning; pathologic process; protozoal antigen; recombinant proteins; serology /serodiagnosis; species difference; surface antigens

Pneumocystis carinii is a major opportunistic pathogen of immunocompromised patients. Because P. carinii cannot be reliably cultured, molecular approaches have been utilized to identify and characterize antigens of this organism. Recombinant antigens can then be used to examine host immune responses to P. carinii infections. We have an ongoing project to characterize the antigens of both rat and human P. carinii. We have previously purified the major surface glycoprotein (MSG) of both rat and human pneumocystis using HPLC. It is necessary to use P. carinii from both sources because the organisms are different species. Subsequently, we identified a number of clones from a cDNA library of rat P. carinii that contain genes encoding for the MSG. These clones are clearly related but not identical, demonstrating that multiple genes encode the MSG. We have continued studies to characterize potential antigens of P. carinii genes. We have cloned a number of human P. carinii MSG genes and have expressed a full-length MSG in two fragments. We developed an ELISA to examine antibody responses to these antigens, and have utilized it to examine sera from patients with or without HIV infection, and with or without a history of PCP, as well as sera from a variety of healthy conrols. In about 15% of healthy patients followed serially we have been able to document changes in antibody titers, suggesting that these individuals have developed reinfection or reactivation of P. carinii infection. We will continue these studies to better understand the epidemiology of P. carinii infection in humans. We have also identified the unique expression site of MSG in human P. carinii, and can now identify the MSG variants that are expressed in a patient with PCP. Within this expression site we have identified a region of tandem repeats that varies among different P. carinii isolates, and thus provides a new method for typing human P. carinii. We are also studying a protein related to kexin, a protease of yeast, that appears to be an antigen of rodent pneumocystis. The goal of this study is to better understand the pathogenesis of P. carinii pneumonia with the hope that we can use this information to control or prevent this disease.

肺炎藻固醇是免疫功能低下患者的主要机会病原体。由于不能可靠地培养carinii，因此已经利用分子方法来识别和表征该生物体的抗原。然后，重组抗原可用于检查宿主对Carinii感染的免疫反应。我们有一个持续的项目来表征大鼠和人类P. carinii的抗原。我们先前使用HPLC纯化了大鼠和人肺炎的主要表面糖蛋白（MSG）。由于生物是不同的物种，因此必须使用两个来源的carinii。随后，我们从大鼠P. carinii的cDNA库中鉴定了许多克隆，这些克隆包含编码味精的基因。这些克隆显然是相关的，但并不相同，表明多个基因编码了味精。我们继续研究以表征carinii基因的潜在抗原。我们已经克隆了许多人类P. carinii msg基因，并在两个片段中表达了全长的味精。我们开发了一种ELISA来检查对这些抗原的抗体反应，并利用它来检查有或没有HIV感染患者的血清，以及有或没有PCP史以及各种健康蛋白酶的血清。在大约15％的健康患者中，我们已经能够记录抗体滴度的变化，这表明这些人已经恢复了或重新激活Carinii感染。我们将继续这些研究，以更好地理解人类的Carinii感染的流行病学。我们还鉴定了人类P. carinii中MSG的独特表达位点，现在可以识别在PCP患者中表达的MSG变体。在此表达位点，我们确定了一个串联重复区域，该区域在不同的carinii分离株之间有所不同，因此提供了一种新方法来键入人类的carinii。我们还正在研究一种与Kexin相关的蛋白质，Kexin是一种酵母的蛋白酶，该蛋白质似乎是啮齿动物肺炎的抗原。这项研究的目的是更好地了解Carinii P. carinii肺炎的发病机理，希望我们可以使用此信息来控制或预防这种疾病。