Abstract
Avian pathogenic Escherichia coli O1 (APEC O1) is a pathogenic bacterium that causes significant economic losses in
the poultry industry and raises concerns about zoonotic infections. The development
of effective vaccines against APEC O1 is essential due to antibiotic resistance and
the potential for severe symptoms in both chickens and humans. In this context, we
have been focusing on the O1A, O1B, and O1C antigen structures derived from E. coli O1 lipopolysaccharide (LPS). In this study, the first synthesis of the pentasaccharide
repeating units of the O1B and O1C antigens was successfully achieved. The synthesis
and immunological evaluation of their conjugates with bovine serum albumin (BSA) were
conducted. Only the O1A-pentasaccharide structure is a glycotope candidate for APEC
O1. Keyhole limpet hemocyanin (KLH)–O1A-pentasaccharide conjugate was also synthesized,
and its immunogenicity was evaluated by the ELISA assay. The efficient production
of antibodies capable of binding to both APEC O1 LPS and the O1A-pentasaccharide structure
was observed, indicating that O1A-pentasaccharide is a promising vaccine candidate
against APEC O1.
Key words
Escherichia coli
- boron-mediated aglycon delivery - glycoconjugates - vaccine - glycotope - stereoselective
synthesis - glycosylation - oligosaccharides
