Chlamydial lipopolysaccharide and atherosclerosis

Abstract

On the first slide you see one aspect of LPS which is relevant for all chlamydial diseases. The lipopolysaccharide is the only major surface antigen which represents the whole genus. All the species which were discovered over the years were shown to have one epitope common to all chlamydia, which at the same time has no cross-reactivity with any other lipopolysaccharide or any other natural compound.

We could clarify this by determining the exact structure of the chlamydiaspecific epitope. On the bottom you see the carbohydrate backbone of chlamydial lipopolysaccharide which is composed of two glycosamines belonging to the lipid A moiety which is present in all lipopolysaccharides and anchors the molecule in the outer membrane. Outside of the membrane we have the trisaccharide of Kdo. Within this trisaccharide we see a chemical structure unique in nature: the interlinkage of two Kdo residues by a 2→8 linkage. The presence of this 2→8 linkage is chemically as well as antigenicaIly unique. Antibodies against Kdo in this type of linkage are chlamydia-specific. I have drawn two types, one is the type C antibody for which the disaccharide alone is already enough to confer this Chlamydia specificity, and the type D antibody recognizes the whole molecule.