Sialyl-Tn antigen expression and O-linked GalNAc-Thr synthesis by Trypanosoma cruzi

Most Trypanosoma cruzi O-glycans are linked to Thr/Ser residues via N-acetylglucosamine. We report that the mucin-type carcinoma-associated sialyl-Tn antigen (NeuAc-GalNAc-O-Ser/Thr) is expressed by T. cruzi. A specific MAb allowed us to localize the antigen on the surface of epimastigotes and to identify reactive components in parasite lysates (32, 60, and 94 kDa). In addition, ppGalNAc-T activity was characterized in epimastigotes, and direct evidence was obtained for the in vitro incorporation of GalNAc to a synthetic peptide derived from a T cruzi mucin. These results add an as yet unknown complexity to the pathways of O-glycan biosynthesis in this protozoan parasite. (C) 2003 Elsevier Inc. All rights reserved.