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標題: Evidence of intracellular stages in Trypanosoma (Megatrypanum) theileri in non-phagocytic mammalian cells
作者: Lee, Yen-Feng
Cheng, Ching-Chang
Chen, Jiun-Sheng
Lin, Nai-Nu
Hung, Yi-Wen
Wang, Jiunn-Min
Tu, Wu-Chun
Tung, Kwong-Chung
Chiu, Yung-Tsung
關鍵字: Trypanosoma theileri;Intracellular stages;Autophagy;Lysosome;TGF- beta
Project: Veterinary Parasitology, Volume 191, page(s) 228– 239.
Trypanosoma (subgenus Megatrypanum) theileri was first identified over one hundred years
ago, and is a widespread parasite in cattle. Its life cycle within the mammalian host has rarely
been reported. Whether there is an intracellular stage in tissues is unknown and such a stage
has not been demonstrated experimentally. Intriguingly, using Giemsa staining with light
microscopy and transmission electron microscopy examination, we found that the parasite
was able not only to attach to cells but also to invade several phagocytic and non-phagocytic
mammalian cells. Based on these findings, we conducted further investigations using a
special antibody in immunofluorescence confocal images. Moreover, we examined a series
of possible events of cell invasion in T. theileri. The results revealed that GM1, a marker of
membrane rafts, was implicated in the mechanism of entry by this parasite. After incubation
with tissue culture trypomastigotes, the gelatinolytic activity was significantly increased
and accumulated at the attachment sites. Using ultrastructural localization detection by
CytoTracker live imaging and confocal immunofluorescence microscopy, we found that
lysosome fusion and the autophagy pathway were engaged in invaginating processes. T.
theileri amastigotes also invaded cells and were enclosed by the lysosomes. Furthermore,
tissue-cultured trypomastigotes were found to be capable of triggering intracellular free
Ca2+ transients and TGF- -signaling. Our findings that intracellular amastigote stages exist
in mammalian cells infected with T. theileri and that the invasion processes involved various
host cell components and cell signalings were extremely surprising and warrant further
ISSN: 0304-4017
DOI: 10.1016/j.vetpar.2012.08.027
Appears in Collections:獸醫學系所

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