Frevert U, Schenkman S, Nussenzweig V
Department of Pathology, Kaplan Cancer Center, New York University Medical Center, New York 10016.
Infect Immun. 1992 Jun;60(6):2349-60. doi: 10.1128/iai.60.6.2349-2360.1992.
We have used antibodies to the Trypanosoma cruzi trans-sialidase and to its product, the host cell invasion-related Ssp-3 epitope, to study the expression of the corresponding antigens during the intracellular development of the parasite and in the extracellular trypomastigotes. As soon as 2 h after host cell invasion, trans-sialidase was no longer detected, whereas the Ssp-3 epitope was still present on intracellular parasites. The amastigotes which subsequently developed remained nonreactive with the antibodies. Expression of enzymatically active T. cruzi trans-sialidase started again only after transformation of the amastigotes into trypomastigotes 72 h after host cell invasion. trans-Sialidase was shed from the trypanosomes into the host cell cytoplasm, where the enzyme accumulated until release of the parasites. All released trypomastigotes expressed trans-sialidase on their surfaces and in the flagellar pockets, but stumpy trypomastigotes were stained more intensely than slender trypomastigotes. Ssp-3, the sialylated reaction product of trans-sialidase, was assembled only after rupture of the host cell membrane and was detected on the plasma membranes and in the flagellar pockets of all trypomastigotes.
我们使用了针对克氏锥虫转唾液酸酶及其产物（与宿主细胞入侵相关的Ssp-3表位）的抗体，来研究相应抗原在寄生虫细胞内发育过程以及细胞外锥鞭毛体中的表达情况。宿主细胞入侵后仅2小时，就检测不到转唾液酸酶了，而Ssp-3表位在细胞内寄生虫上仍然存在。随后发育的无鞭毛体与这些抗体仍无反应。只有在宿主细胞入侵72小时后无鞭毛体转化为锥鞭毛体后，具有酶活性的克氏锥虫转唾液酸酶的表达才再次开始。转唾液酸酶从锥虫释放到宿主细胞细胞质中，该酶在那里积累，直至寄生虫释放。所有释放的锥鞭毛体在其表面和鞭毛袋中都表达转唾液酸酶，但粗短型锥鞭毛体的染色比细长型锥鞭毛体更强烈。转唾液酸酶的唾液酸化反应产物Ssp-3仅在宿主细胞膜破裂后组装，并在所有锥鞭毛体的质膜和鞭毛袋中被检测到。
