Synthesis of neoglycoproteins containing Kdo epitopes specific for Chlamydophila psittaci lipopolysaccharide

The oligosaccharides alpha-Kdop-(2-->8)-alpha-Kdop-(2-->6)-beta-D-GlcpNAc-( 1-->OAll) 4, alpha-Kdop-(2-->4)-alpha-Kdop-(2-->4)-alpha-Kdop-(2-->6)-beta- D-GlcpNAc-(1-->OAll) 10, and the branched Kdo tetrasaccharide alpha-Kdop-(2 -->4)-[alpha Kdop-(2-->8)-alpha-Kdop-(2-->4)-alpha-Kdop-(2-->OAll) 21 have been prepared using en bloc transfer of Kdo oligosaccharide bromide donors to protected mono- or disaccharide accepters. Radical addition of cysteamin e to the anomeric allyl glycosides afforded good yields of the correspondin g 3-(2-aminoethylthio)propyl glycosides 5, 11 and 22. The spacer ligands we re activated with thiophosgene and reacted with bovine serum albumin to giv e the neoglycoconjugates 6, 12 and 23 which were used to prepare solid-phas e antigens in enzyme immune-assays for the characterization of monoclonal a ntibodies against chlamydial LPS. The data showed that the (2-->8)-linked K do disaccharide and the (2-->8)-(2-->4)-linked Kdo trisaccharide portion of the neoglycoconjugate 23 were not available for binding of antibodies whic h recognize these structures as di- and trisaccharide, respectively.