Aji T, Flanigan T, Marshall R, Kaetzel C, Aikawa M
Department of Parasitology, Okayama University Medical School, Japan.
J Protozool. 1991 Nov-Dec;38(6):82S-84S.
The lack of a well-defined in vitro model of Cryptosporidium infection has severely hampered research on the biology of parasitic invasion of the host cell and on intracellular development of the parasite. In vitro infection of the differentiated human enterocyte cell line HT29.74 was studied by electron microscopy to detect changes in parasite and host cell morphology. Cryptosporidium oocysts obtained from AIDS patients were applied to a monolayer of cloned differentiated HT29.74 cells. Parasites and infected cells were evaluated by transmission electron microscopy at 20 min, 1 h, 6 h, 24 h and 7 days. Sporozoite invagination within the epithelial cell microvilli and subsequent penetration was evident at 1 h. At 6 h, the development of a dense band and feeder layer was visible. Development of the trophozoite into a schizont occurred over 24 h. Micronemes and dense granules were clearly visible within sporozoites and merozoites. Organization of vacuoles within the cytoplasm of the host cell was evident below the dense band. A sexual Cryptosporidium development in vitro was morphologically no different from initial development in vivo. In vitro infection of HT29.74 cells provides an excellent model to study parasite-host cell interaction and asexual parasite development.
缺乏明确的隐孢子虫感染体外模型严重阻碍了对寄生虫侵袭宿主细胞生物学以及寄生虫细胞内发育的研究。通过电子显微镜研究分化的人肠上皮细胞系HT29.74的体外感染，以检测寄生虫和宿主细胞形态的变化。将从艾滋病患者获得的隐孢子虫卵囊应用于克隆分化的HT29.74细胞单层。在20分钟、1小时、6小时、24小时和7天时通过透射电子显微镜评估寄生虫和感染细胞。1小时时可见子孢子在上皮细胞微绒毛内陷入并随后穿透。6小时时，可见致密带和滋养层的形成。滋养体发育成裂殖体发生在24小时内。在子孢子和裂殖子内可清楚看到微线体和致密颗粒。在致密带下方，宿主细胞质内液泡的组织明显可见。体外隐孢子虫的有性发育在形态上与体内的初始发育没有差异。HT29.74细胞的体外感染为研究寄生虫-宿主细胞相互作用和寄生虫无性发育提供了一个极好的模型。
