Human Onchocerca volvulus infection sera were found to recognize zwitterionic glycolipids of O. volvulus and to cross-react with those of other parasitic nematodes (Ascaris suum, Setaria digitata and Litomosoides sigmodontis). By the use of an epitope-specific monoclonal antibody, zwitterionic glycolipids of all these nematode species were observed to contain the antigenic determinant phosphocholine. A hyperimmune serum specific for arthro-series glycolipid structures reacted with the various neutral glycolipids of all these nematodes, which demonstrated that their oligosaccharide moieties belonged to the arthro-series of protostomial glycolipids. These results indicated that arthro-series glycosphingolipids carrying, in part, phosphocholine substituents, represent highly conserved, antigenic glycolipid markers of parasitic nematodes. Three glycolipid components of the O. volvulus zwitterionic fraction were structurally characterized by matrix-assisted laser-desorption/ionization time-of-flight MS, methylation analysis and exoglycosidase treatment. Their chemical structures were elucidated to be phosphocholine-6GlcNAc(β1-3)Man(β1-4)Glc(1-1)ceramide, GalNAc(β1-4)[phosphocholine-6]GlcNAc(β1-3)Man(β1-4)Glc(1-1)ceramide and Gal(α1-3)GalNAc(β1-4)[phosphocholine-6]GlcNAc(β1-3)Man(β1-4)Glc(1-1)ceramide for the zwitterionic ceramide tri-, tetra- and penta-hexosides respectively. The ceramide composition was found to be dominated by 2-hydroxylated docosanoic (C22h:0), tricosanoic (C23h:0) and tetracosanoic (C24h:0) acids, and C17 sphingosine (Cd17:1) (where h is hydroxylated and d is dihydroxylated).

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