S-linked ganglioside analogues for use in conjugate vaccines.

[structure: see text] Glycosidase resistant thioglycoside precursors of the melanoma-associated ganglioside GM(2) have been synthesized starting from lactose. Syntheses of several analogues of ganglioside GM(3) and a positional isomer have been developed. These compounds contain thio-linked sialic acid residues and a modified ceramide aglycon functionalized for coupling to proteins, surfaces, or matrices. The hydrolytic stability of these oligosaccharides enhances the immunogenicity of the corresponding conjugate vaccines by ensuring their integrity in the acidic compartments of antigen processing cells.