Stage-specific expression and intracellular shedding of the cell surface trans-sialidase of Trypanosoma cruzi.
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.
Frevert
U
U
Department of Pathology, Kaplan Cancer Center, New York University Medical Center, New York 10016.
Schenkman
S
S
Nussenzweig
V
V
D000818:Animals; D000939:Epitopes / Q000032:analysis; D005455:Fluorescent Antibody Technique; D016253:Microscopy, Immunoelectron; D009439:Neuraminidase / Q000032:analysis* / Q000276:immunology; D014349:Trypanosoma cruzi / Q000201:enzymology* / Q000276:immunology / Q000302:isolation & purification
D000939:Epitopes; D009439:Neuraminidase