MOLECULAR BIOLOGY OF PNEUMOCYSTIS CARINII

卡氏肺孢子虫是患者最重要的肺部病原体 获得性免疫缺陷综合症（艾滋病）。 尽管作出了重大的 卡氏肺孢子虫的诊断、治疗和预防的改进 尽管如此，它仍然是艾滋病发病率和死亡率的主要原因。 病原体长期以来被认为是原生动物的一员。 该实验室和其他实验室的研究表明，卡氏肺孢子虫是 实际上是真菌的一员 卡氏肺吸虫的生物学和病理学研究一直受到阻碍 由于缺乏体外培养系统。 虽然抗原识别在 正常的免疫反应已经部分地表征为 分子大小和定位在完整的卡氏肺孢子虫，不能 在长期培养中保持卡氏肺孢子虫， 这些分子在体内发挥的作用。 卡氏肺孢子虫的主要表面抗原是糖蛋白gp116， 与真菌细胞表面有几个共同的生化特征 甘露糖蛋白 gp116基因组和cDNA片段的分离 已经实现，并且已经显示GP 116是高度可变的蛋白质。 的 这种变化的来源和程度尚不清楚，将进行调查 用聚合酶链反应扩增gp116基因和cDNA， 单一生物体 这允许评估可变性和洞察力 变异性在逃避免疫反应中的潜在作用。 该提案的另一个目标是进一步表征克隆的 编码P. carinii。 这些抗原在近缘真菌中的表达可能 有助于阐明这些分子在卡氏肺孢子虫本身中的功能。 通过利用卡氏毕赤酵母与酵母的密切关系， 酵母中的类似分子将被分离。 鉴定这些 卡氏肺孢子虫表面抗原的酵母同系物将允许详细的 这些细胞表面分子的结构和功能分析。 详细表征的结构和致病作用， P.卡氏体表面抗原将扩展我们对卡氏体生物学的理解， 这种神秘的有机体，也许会为人类的 卡氏肺孢子虫肺炎的治疗和控制。

Pneumocystis carinii is the most significant pulmonary pathogen in patients with the acquired immunodeficiency syndrome (AIDS). Despite substantial improvements in the diagnosis, treatment and prophylaxis of P. carinii pneumonia, it remains a leading cause of morbidity and mortality in AIDS. the causative agent was long considered to be a member of the Protozoa. Studies from this laboratory and others has demonstrated that P. carinii is in fact a member of the Fungi. Research into the biology and pathobiology of P. carinii has been hampered by the lack of an in vitro culture system. While antigens recognized in the normal immune response have been partially characterized in terms of molecular size and localization on intact P. carinii, the inability to maintain P. carinii in long-term culture has prevented the analysis of the role that these molecules play in vivo. The major surface antigen of P. carinii is the glycoprotein gp116 which shares several biochemical characteristics with fungal cell surface mannoproteins. The isolation of genomic and cDNA fragments encoding gp116 has been achieved and has shown gp116 to be a highly variable protein. The source and extent of this variability is not known and will be investigated using the polymerase chain reaction to amplify gp116 genes and cDNAs from single organisms. This allows an assessment of the variability and insight into the potential role of variability in evading the immune response. Another one of the goals of this proposal is to further characterize cloned gene fragments encoding the major surface antigens (gp116 and others) of P. carinii. The expression of these antigens in closely-related Fungi may help to elucidate the function of these molecules within P. carinii itself. by taking advantage of the close relationship of P. carinii to the yeasts, similar molecules in yeast will be isolated. The identification of these yeast homologs of P. carinii surface antigens will allow the detailed structural and functional analysis of these cell surface molecules. The detailed characterization of the structural and pathogenic roles of the P. carinii surface antigens will extend our understanding of the biology of this enigmatic organism and perhaps shed new light on strategies for the treatment and control of P. carinii pneumonia.