Fuc(α1→3)GaINAc-:: the major antigenic motif of Schistosoma mansoni glycolipids implicated in infection sera and keyhole-limpet haemocyanin cross-reactivity

The aim of the present study was the characterization of the dominant epitope present on Schistosoma mansoni glycolipids, which causes cross-reactivity of S. mansoni and S. haematobium infection sera with keyhole-limpet haemocyanin (KLH). To this end, the monoclonal antibody M2D3H was chosen for its similar behaviour in high-performance TLC immunostaining and inhibition-ELISA to infection sera. Individual, structurally defined oligosaccharides derived from S. mansoni egg glycolipids were tested for their binding to this monoclonal antibody by immunoaffinity chromatography. A terminal fucose residue linked in the (alpha1 --> 3) position to N-acetylgalactosamine was found to be the common structural determinant of the four oligosaccharides binding to M2D3H. The Fuc(alpha1 --> 3)GalNAc motif also appeared to be the basis for the cross-reactivity with KLH, a phenomenon used in the serodiagnosis of S. mansoni, S. haematobium and S. japonicum infections.