Leprosy-specific neoglycoconjugates: Synthesis and application to serodiagnosis of leprosy

This chapter discusses leprosy-specific neoglycoconjugates (NGCs). The first generation of NGCs were capable of specific recognition of anti-phenolic glycolipid I (PGL-I) antibodies in sera from patients with lepromatous leprosy. The chapter focuses on the NGCs synthesized in the laboratories of Brennan, Fujiwara and others, and Gigg and others. All of the syntheses, whether involving the entire trisaccharide unit or the outermost disaccharide, were accomplished by a stepwise glycosylation from the innermost residue that contained a glycosidically attached linker arm in configurationally correct form. Two basic strategies were used for the conjugation to protein, usually bovine serum albumin (BSA), through covalent linkage to the ε-amino groups of lysine residues. In one approach, the innermost glycosyl residue was assembled as a glycoside bearing an alkoxycarbonyl group for conversion via acylhydrazide to an acyl azide for coupling with lysine residues. Indirect enzyme linked immunosorbent assay (ELISA) is the method of choice for the application of the NGCs to the detection of anti-PGL-I antibodies in the serodiagnosis of leprosy.