[4)-[beta-D-Glcp-(1->6)]-[alpha-L-Rhap-(1->3)]-alpha-D-Glcp-(1->3)-alpha-L-Rhap2Ac-(1->3)-beta-D-GlcpNAc-(1->]n
[4)-[beta-d-glcp-(1->6)]-[alpha-l-rhap-(1->3)]-alpha-d-glcp-(1->3)-alpha-l-rhap2ac-(1->3)-beta-d-glcpnac-(1->]n
A polysaccharide derivative with a pentasaccharide repeat unit consisting of α-<small>D</small>-glucosyl, 2-<em>O</em>-acetyl-α-<small>L</small>-rhamnosyl and <em>N</em>-acetyl-β-<small>D</small>-glucosaminyl residues all linked (1→3), to the α-glucosyl residue of which are attached a β-<small>D</small>-glucosyl residue and an α-<small>L</small>-rhamnosyl residue via (1→6) and (1→3) linkages respectively, with all repeat units being linked (1→4). The repeat unit corresponds to that of the native <em>Escherichia coli</em> serotype O25B <em>O</em>-antigen.