Figure 1. Identifying and connecting minimal glycan epitopes to mimic larger glycans.

During C. difficile infections (CDIs), patients mount antibodies to the PS-I polysaccharide. In efforts towards rationally designed vaccines, various PS-I glycan epitopes were synthesized⁷. A disaccharide minimal epitope (dashed lines) was identified from recognition patterns of human and mouse anti-PS-I antibodies⁷. (a) Mice immunized with a semi-synthetic glycoconjugate vaccine candidate of CRM₁₉₇ and the disaccharide produce antibodies to the pentasaccharide repeating unit and smaller substructures. (b) A fully synthetic pentavalent glycan mimic with increased antigenicity compared with monovalent disaccharides elicits antibodies to the pentasaccharide only. It comprises an OAA backbone²³,²⁴,²⁵ and a T-cell epitope, amino acids 366–383 of the CRM₁₉₇ protein²⁶.