Figure 4.

Lewis antigen structures. Helicobacter pylori can produce type 1 (based on a β-(1,3)-linked galactose-GlcNAc sugar backbone) and type 2 (based on a β-(1,4)-linked galactose-GlcNAc sugar backbone) Lewis antigens. Le^a and Le^x are built by addition of a fucose residue to the GlcNAc sugar of the type 1 and type 2 backbone, through α-(1,4) or α-(1,3) linkages, respectively. Le^b and Le^Y are built by addition of a fucose residue through α-(1,2) linkage to Le^a and Le^x structures, respectively. Sialyl-Le^x (SLe^x) is built by addition of a sialyl group to the Le^x antigen by a α-(2,3) linkage.