Studies on vaccines against cholera. Synthesis of neoglycoconjugates from the hexasaccharide determinant of Vibrio cholerae O : 1, serotype Ogawa, bysingle-point attachment or by attachment of the hapten in the form of clusters

The terminal hexasaccharide of the O-antigen of Vibrio cholerae O:1, seroty pe Ogawa, has been synthesized in the form of a glycoside whose aglycon (li nker) allows conjugation to carrier proteins by reductive amination. The co njugate obtained from direct, single-point attachment of the linker-equippe d hapten to chicken serum albumin (CSA) contained seven hapten residues/CSA . A neoglycoconjugate containing the carbohydrate antigen in the form of cl usters was obtained using, as a hapten subcarrier, an oligopeptide containi ng 16 amino groups. It was treated with a limited amount of hapten, to give a hapten-carrying subcarrier (HCS). Subsequent conjugation of HCS to CSA, using squaric acid diethyl ester as a conjugation reagent, gave a cross-lin ked, glycocluster conjugate containing 51% (w/w) of the carbohydrate. Publi shed by Elsevier Science Ltd.