Gagliardo L F, McVay C S, Appleton J A
James A. Baker Institute for Animal Health, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA.
Infect Immun. 2002 Apr;70(4):1853-9. doi: 10.1128/IAI.70.4.1853-1859.2002.
Trichinella spiralis is an obligate parasite of animals that has an unusual intracellular life cycle. Investigation of parasitism at the cellular and molecular levels has been challenging because of a shortage of tools for in vitro cultivation of T. spiralis. We have found that T. spiralis larvae molt, ecdyse, develop to adulthood, and reproduce when they are inoculated onto cultured intestinal epithelial cells. Initially, larvae invade and migrate through cells in a monolayer (T. ManWarren, L. Gagliardo, J. Geyer, C. McVay, S. Pearce-Kelling, and J. Appleton, Infect. Immun. 65:4806-4812, 1997). During prolonged culture in Caco-2 epithelial cells, L1 larvae molted and ecdysed with efficiencies as high as 50%. Molting and ecdysis in vitro required entry of the parasite into cells; conditions that prevented entry into cells also prevented ecdysis. When larvae were inoculated at a low density and cultured for 5 to 9 days, as many as 50% of the larvae developed to adult stages. Low numbers of mature male worms with copulatory appendages were observed in these cultures. The majority of worms that survived for five or more days were unfertilized females. Low-density cultures supported development of female worms with embryos at rates of 4 to 5%. These results show that the intestinal life cycle of T. spiralis can be supported entirely by host epithelial cells. Our model should allow more detailed investigation of intracellular parasitism by T. spiralis.
旋毛虫是动物的专性寄生虫，具有独特的细胞内生命周期。由于缺乏旋毛虫体外培养工具，在细胞和分子水平上研究其寄生现象具有挑战性。我们发现，将旋毛虫幼虫接种到培养的肠上皮细胞上时，它们会蜕皮、蜕化，发育至成虫并进行繁殖。最初，幼虫侵入并穿过单层细胞迁移（T. ManWarren、L. Gagliardo、J. Geyer、C. McVay、S. Pearce-Kelling和J. Appleton，《感染与免疫》65:4806 - 4812，1997年）。在Caco - 2上皮细胞中长时间培养期间，L1幼虫蜕皮和蜕化的效率高达50%。体外蜕皮和蜕化需要寄生虫进入细胞；阻止进入细胞的条件也会阻止蜕化。当以低密度接种幼虫并培养5至9天时，多达50%的幼虫发育至成虫阶段。在这些培养物中观察到少量带有交配附属器的成熟雄虫。存活5天或更长时间的大多数蠕虫是未受精的雌虫。低密度培养支持4%至5%的带有胚胎的雌虫发育。这些结果表明，旋毛虫的肠道生命周期可以完全由宿主上皮细胞支持。我们的模型应该能够更详细地研究旋毛虫的细胞内寄生现象。
