streptococcal polysaccharide Ia group B;alpha-Neup5Ac-(2->3)-beta-D-Galp-(1->4)-beta-D-GlcpNAc-(1->3)-[beta-D-Glcp-(1->4)]-beta-D-Galp;β-D-Galactopyranose, O-(N-acetyl-α-neuraminosyl)-(2→3)-O-β-D-galactopyranosyl-(1→4)-O-2-(acetylamino)-2-deoxy-β-D-glucopyranosyl-(1→3)-O-[β-D-glucopyranosyl-(1→4)]- (9CI)