A Semi-synthetic Oligosaccharide Conjugate Vaccine Candidate Confers Protection against Streptococcus pneumoniae Serotype 3 Infection

Cell Chem Biol. 2016 Nov 17;23(11):1407-1416. doi: 10.1016/j.chembiol.2016.09.016. Epub 2016 Nov 3.


The identification of immunogenic glycotopes that render glycoconjugate vaccines protective is key to improving vaccine efficacy. Synthetic oligosaccharides are an attractive alternative to the heterogeneous preparations of purified polysaccharides that most marketed glycoconjugate vaccines are based on. To investigate the potency of semi-synthetic glycoconjugates, we chose the least-efficient serotype in the current pneumococcal conjugate vaccine Prevnar 13, Streptococcus pneumoniae serotype 3 (ST3). Glycan arrays containing synthetic ST3 repeating unit oligosaccharides were used to screen a human reference serum for antibodies and to define the recognition site of two ST3-specific protective monoclonal antibodies. The glycan array screens identified a tetrasaccharide that was selected for in-depth immunological evaluation. The tetrasaccharide-CRM197 carrier protein conjugate elicited protective immunity as evidenced by opsonophagocytosis assays and protection against pneumonia caused by ST3 in mice. Formulation of the defined protective lead candidate glycotope has to be further evaluated to elicit optimal long-term immunity.

Keywords: Epitope mapping; Glycan arrays; Glycoconjugate vaccines; Opsonophagocytosis; Streptococcus pneumoniae; Synthetic glycans.

MeSH terms

  • Animals
  • Cell Line
  • Female
  • Humans
  • Immunization
  • Mice
  • Mice, Inbred C57BL
  • Oligosaccharides / chemistry
  • Oligosaccharides / immunology
  • Oligosaccharides / therapeutic use*
  • Pneumococcal Infections / immunology
  • Pneumococcal Infections / prevention & control*
  • Pneumococcal Vaccines / chemistry
  • Pneumococcal Vaccines / immunology
  • Pneumococcal Vaccines / therapeutic use*
  • Streptococcus pneumoniae / immunology*
  • Vaccines, Conjugate / chemistry
  • Vaccines, Conjugate / immunology
  • Vaccines, Conjugate / therapeutic use*


  • 13-valent pneumococcal vaccine
  • Oligosaccharides
  • Pneumococcal Vaccines
  • Vaccines, Conjugate