Chávez B, González-Mariscal L, Cedillo-Rivera R, Martínez-Palomo A
Department of Experimental Pathology, Centro de Investigación y de Estudios Avanzados, Mexico City, Mexico.
Exp Parasitol. 1995 Feb;80(1):133-8. doi: 10.1006/expr.1995.1015.
The variable clinical course of human giardiasis may be due in part to differences in the virulence of various strains of Giardia lamblia. To address this issue, the in vitro cytopathic effect of isolates obtained from human symptomatic or asymptomatic infections was assessed by ultrastructural and electrophysiological methods. Axenic trophozoites of 10 strains of G. lamblia isolated from children with infections in Mexico City were cultured for 12 to 24 hr on live MDCK epithelial cells. No decrease in transepithelial resistance of MDCK monolayers mounted in Ussing chambers was detected with any of the isolates analyzed. On the contrary, trophozoites or media in which the isolates grew produced up to a twofold increase in transepithelial resistance. Transmission and scanning electron microscopy revealed that all isolates of G. lamblia, irrespective of their origin, gave rise to focal regions of microvilli depletion. These modifications were induced by the close attachment of the ventrolateral flange of the parasite adhesive disk to the apical surface of MDCK cells. The circular imprints evolved progressively to larger areas devoid of microvilli. In conclusion, under in vitro conditions, isolates of G. lamblia trophozoites derived from symptomatic or asymptomatic human infections damage epithelial cultured cells mainly by depleting their microvilli. None of the isolates showed evidence of an invasive effect.
人类贾第虫病的临床病程多变，部分原因可能是不同株系的蓝氏贾第鞭毛虫毒力存在差异。为解决这一问题，通过超微结构和电生理方法评估了从有症状或无症状人类感染中分离出的菌株的体外细胞病变效应。从墨西哥城感染儿童中分离出的10株蓝氏贾第鞭毛虫的无菌滋养体在活的MDCK上皮细胞上培养12至24小时。在所分析的任何分离株中，均未检测到安装在尤斯室中的MDCK单层跨上皮电阻降低。相反，分离株生长的滋养体或培养基使跨上皮电阻增加了两倍。透射电子显微镜和扫描电子显微镜显示，所有蓝氏贾第鞭毛虫分离株，无论其来源如何，都会导致微绒毛缺失的局部区域。这些改变是由寄生虫粘附盘腹侧边缘紧密附着于MDCK细胞顶端表面引起的。圆形印记逐渐演变为更大的无微绒毛区域。总之，在体外条件下，从有症状或无症状人类感染中分离出的蓝氏贾第鞭毛虫滋养体分离株主要通过消耗微绒毛来损伤培养的上皮细胞。没有分离株显示出侵袭作用的证据。
