Structurally defined helminth glycan-ovalbumin conjugates reveal epitope-dependent dendritic cell uptake

Helminth infections impose a substantial global health burden, with parasite glycoconjugates and their glycan epitopes playing critical roles in host immune recognition and immunomodulation. However, systematic investigation of structure-activity relationships is impeded by the structural complexity and heterogeneity of helminth glycans, limiting the availability of homogeneous materials. Here, we report a modular chemoenzymatic strategy for generating eleven structurally defined helminth glycans bearing signature epitopes, including LacdiNAc (LDN) and fucosylated LacdiNAc (LDNF) terminal motifs, as well as core α1,3-fucose and core β1,2-xylose modifications in N-glycans. A panel of truncated glycosyltransferases (CeGalNAcT, SmFucT-E, ZmXylT, and ZmFucT) expressed in insect cells enabled regio- and stereoselective glycan assembly. Eight representative N-glycans were conjugated to ovalbumin (OVA), labeled with fluorescein isothiocyanate (FITC), and assessed for cellular association and internalization using primary murine bone marrow-derived dendritic cells (BMDCs), with DC2.4 cells employed for comparative characterization. Active internalization was distinguished from surface binding through temperature-controlled uptake assays, confocal microscopy, and receptor inhibition experiments. Terminal epitopes, especially LDNF, significantly promoted dendritic cell uptake compared with OVA-FITC; Under the conditions tested, combining terminal epitopes with core modifications did not further increase uptake relative to terminal epitopes alone. Receptor inhibition experiments supported the involvement of Ca²⁺-dependent glycan recognition and multiple lectin-mediated pathways. Collectively, this work establishes an efficient platform for accessing homogeneous helminth glycans and reveals how defined carbohydrate epitopes shape glycoconjugate recognition by dendritic cells.