Forney J R, Vaughan D K, Yang S, Healey M C
Department of Animal, Dairy, and Veterinary Sciences, College of Agriculture, Utah State University, Logan 84322, USA.
J Parasitol. 1998 Oct;84(5):908-13.
The present study investigated the role of actin polymerization and myosin motor protein activity in the gliding motility of Cryptosporidium parvum sporozoites. Short motility trails were detected using an indirect immunofluorescent assay (IFA) with a polyclonal antisporozoite antibody following incubation of sporozoites on poly-L-lysine-coated glass slides. Sporozoite motility was blocked following exposure to cytochalasin D, a myosin light-chain kinase inhibitor 1-(5-iodonaphthalene-1-sulfonyl)-1H-hexhydro-1,4-diazapin e, and the myosin ATPase inhibitor 2,3-butanedione monoxime. Sporozoites were observed to form rounded, blunt-ended shapes when exposed to these same inhibitors. Incubation of purified oocysts with these compounds did not significantly inhibit in vitro excystation or subsequent infectivity in cultured epithelial cells. Indirect IFA revealed a uniform distribution of actin protein throughout the body of the sporozoite; immunoelectron microscopy confirmed a diffuse intracellular pattern of gold particles in excysted sporozoites. Collectively, these findings show that sporozoite motility is dependent upon an intact actin-myosin motor system, and the dynamic interaction of F-actin and myosin motor proteins has a further role in maintaining the structural integrity of excysted sporozoites. Further, in vitro excystation and infectivity of C. parvum occurs in the absence of dynamic sporozoite locomotion.
本研究调查了肌动蛋白聚合作用和肌球蛋白运动蛋白活性在微小隐孢子虫子孢子滑行运动中的作用。在子孢子于聚-L-赖氨酸包被的载玻片上孵育后，使用多克隆抗子孢子抗体通过间接免疫荧光测定法（IFA）检测到短的运动轨迹。在暴露于细胞松弛素D（一种肌球蛋白轻链激酶抑制剂1-(5-碘萘-1-磺酰基)-1H-六氢-1,4-二氮杂䓬）和肌球蛋白ATP酶抑制剂2,3-丁二酮单肟后，子孢子运动被阻断。当暴露于这些相同的抑制剂时，观察到子孢子形成圆形、钝端形状。用这些化合物孵育纯化的卵囊并未显著抑制体外脱囊或随后在培养上皮细胞中的感染性。间接IFA显示肌动蛋白在子孢子体内呈均匀分布；免疫电子显微镜证实脱囊后的子孢子中金颗粒呈弥漫性细胞内模式。总体而言，这些发现表明子孢子运动依赖于完整的肌动蛋白-肌球蛋白运动系统，并且F-肌动蛋白和肌球蛋白运动蛋白的动态相互作用在维持脱囊后的子孢子结构完整性方面还有进一步作用。此外，微小隐孢子虫的体外脱囊和感染性在没有动态子孢子运动的情况下发生。
