Erlandsen S L, Bemrick W J, Schupp D E, Shields J M, Jarroll E L, Sauch J F, Pawley J B
Department of Cell Biology & Neuroanatomy, University of Minnesota, Minneapolis 55455.
J Histochem Cytochem. 1990 May;38(5):625-32. doi: 10.1177/38.5.2332623.
We describe here the ultrastructural localization of Giardia cyst antigens in the filaments associated with the outer portion of intact cysts and on developing cyst wall filaments in encysting trophozoites. Post-embedding immunogold labeling of thin sections of intact Giardia cysts with polyclonal and monoclonal antibodies specific for cyst wall antigens (major protein bands of approximately 29, 75, 88, and 102 KD on Western blots) showed strong labeling of the filamentous cyst wall, whereas no labeling was seen on the membranous portion. High-resolution field emission scanning electron microscopy (FESEM) of Giardia cysts revealed that the cyst wall-specific polyclonal rabbit antisera and monoclonal mouse antibody produced gold labeling of 20-nm filaments in the cyst wall as detected with secondary electron imaging (SEI) and backscatter electron imaging (BEI) at 10 kV, despite coating of the cells with platinum by ion sputtering. FESEM studies of encysting Giardia trophozoites demonstrated that immunostaining with antibodies to cyst wall antigens produced colloidal gold labeling of developing cyst wall filaments on the cell surface; however, the intervening membrane domains were unlabeled. Substitution of normal serum for cyst wall-specific antibodies, or preabsorption of specific antibodies with Giardia cysts, eliminated immunolabeling of the filaments.
我们在此描述了贾第虫包囊抗原在与完整包囊外部相关的细丝以及正在形成包囊的滋养体中发育的包囊壁细丝上的超微结构定位。用针对包囊壁抗原（在蛋白质免疫印迹上约为29、75、88和102KD的主要蛋白条带）的多克隆和单克隆抗体对完整贾第虫包囊的薄片进行包埋后免疫金标记，结果显示丝状包囊壁有强烈标记，而膜部分未见标记。贾第虫包囊的高分辨率场发射扫描电子显微镜（FESEM）显示，尽管通过离子溅射用铂对细胞进行了包被，但在10 kV下通过二次电子成像（SEI）和背散射电子成像（BEI）检测到，针对包囊壁的多克隆兔抗血清和单克隆小鼠抗体在包囊壁中对20纳米细丝产生了金标记。对正在形成包囊的贾第虫滋养体的FESEM研究表明，用针对包囊壁抗原的抗体进行免疫染色会在细胞表面对正在发育的包囊壁细丝产生胶体金标记；然而，中间的膜区域未被标记。用正常血清替代针对包囊壁的抗体，或用贾第虫包囊对特异性抗体进行预吸收，可消除细丝的免疫标记。
