Antigenicity evaluation of the synthetic trisaccharides related to Plesiomonas shigelloides serotype O51 O-antigen containing an acetamidino group.

Bacterial surface polysaccharides are widely decorated with diverse rare functional groups. An understanding of the role of these functional groups in immunological activity of the glycans is required for the development of carbohydrate-based treatment against bacterial infectious diseases. Here, the antigenicity evaluation of synthetic trisaccharide 1 related to Plesiomonas shigelloides serotype O51 lipopolysaccharide (LPS) O-antigen and its acetamido derivative 2 was achieved to elucidate the immunological importance of O-antigen structure. The rabbit antisera with high titers of IgG and IgM were collected after immunization with purified P. shigelloides serotype O51 LPS. Glycan microarray screening results showed that both IgG and IgM in rabbit antisera bound specifically to trisaccharides 1 and 2, indicating that the trisaccharide repeating unit is a key antigenic epitope of P. shigelloides serotype O51 O-antigen, while the acetamidino group has no influence on the antigenicity. This finding provides key information for glycoconjugate vaccine design for P. shigelloides serotype O51.