Fig. 1: Overview of the synthesis and immunological evaluation of dPNAG-CRM197 glycoconjugates.

Oligo-β-(1 → 6)-D-glucosamine derivatives (DP4–18) were synthesized via an efficient n + 2 glycosylation strategy using a N-phthaloyl glucosamine disaccharide thiocresol-based donor. Controlled acetylation yielded dPNAG glycans with defined degrees of polymerization and 40–60% N-acetylation. These glycans were used to construct glycan microarrays, which detected anti-dPNAG antibodies in sera from patients infected with A. baumannii and S. pneumoniae. In a separate study, selected glycans were conjugated to CRM197 and used to immunize mice, eliciting robust IgG responses. Immunogenicity and functional activity of the antisera were assessed by glycan arrays and opsonophagocytic killing (OPK) assays.