TERMINAL BETA-LINKED TYVELOSE CREATES UNIQUE EPITOPES IN TRICHINELLA-SPIRALIS GLYCAN ANTIGENS

Indirect evidence that the immunodominant N-glycans of the parasite, T richinella spiralis are capped by novel beta-linked 3,6-dideoxy-D-arab inohexopyranosyl residues (tyvelose, Tyv) was obtained from immunochem ical assays employing monoclonal antibodies and synthetic oligosacchar ides. Three of four previously characterized monoclonal antibodies gen erated from the lymphocytes of T. spiralis infected rats bind BSA glyc oconjugates bearing the synthetic epitope beta-D-Tyvp(1 --> 3)-beta-D- GalNAcp but not to the corresponding alpha-D-Tyvp(1 --> 3)-beta-D-GalN Acp-BSA glycoconjugate, Monosaccharide and disaccharide glycoside inhi bition data mirrors the results of the direct binding experiments. The branched tetrasaccharide beta-D-Tyv(1 --> 3)-beta-D-GalNAcp(1 --> 4)[ alpha-L-Fucp(1 --> 3)]beta-D-GlcNAcp is the most active synthetic olig osaccharide inhibitor for all four monoclonal antibodies studied, whil e the corresponding alpha-D-Tyv containing tetrasaccharide and the cor e trisaccharide beta-D-GalNAcp(1 --> 4)[alpha-L-Fucp(1 --> 3)]beta-D-G lcNAcp are inactive. The exceptional inhibitory activity of the disacc haride beta-D-Tyvp(1 --> 3)-beta-D-GalNAcp with one mAb (18H) compared to that of the branched tetrasaccharide beta-D-Tyvp(1 --> 3)-beta-D-G alNAcp(1 --> 4)[alpha-L-Fucp(1 --> 3)]-beta-D-GlcNAcp is indicative of the presence of linear, nonfucosylated glycan epitopes (beta-D-Tyvp(1 --> 3)-beta-D-GalNAcp(1 --> 4) beta-D-GlcNAcp) that lack a fucose res idue in one arm of the antigenic, tetra-anternary N-glycan. This obser vation supports earlier FAB-mass spectrometry evidence for the existen ce of tetra-antennary, core fucosylated glycans that lack a fucose res idue on one of their antennae.