Exploring the Group B Streptococcus capsular polysaccharides: the structural diversity provides the basis for...

Area of Science:

• Vaccinology
• Analytical Chemistry
• Microbiology

Background:

• Carbohydrate-based vaccines are crucial for preventing bacterial infections like meningitis and pneumonia.
• Group B Streptococcus (GBS) causes severe neonatal infections, yet no vaccine is available.
• High-field Nuclear Magnetic Resonance (NMR) spectroscopy is effective for monitoring carbohydrate vaccine manufacturing.

Purpose of the Study:

• To review structural differences in GBS capsular polysaccharide (CPS) types (Ia, Ib, II-VIII).
• To explore the utility of unique NMR proton profiles for vaccine characterization.
• To establish an identity assay for GBS monovalent vaccine bulks.

Main Methods:

• Analysis of repeating unit structures of GBS CPS types using high-field NMR spectroscopy.
• Identification of unique NMR proton profiles for each GBS CPS type.
• Selection of well-resolved signals in anomeric, NeupNAc methylene (C3), and N-Acetyl regions.

Main Results:

• Distinct NMR proton profiles were observed for different GBS CPS types.
• Specific signals in the anomeric, C3 methylene, and N-Acetyl regions are suitable for identity assays.
• A proof of concept demonstrated identity testing of a GBS CPS type Ia, Ib, III trivalent vaccine using selected anomeric signals.

Conclusions:

• NMR spectroscopy provides unique fingerprints for GBS CPS types, enabling vaccine characterization.
• The identified NMR signals can form the basis of a robust identity assay for GBS vaccines.
• NMR-based identity testing is feasible for both monovalent and multivalent GBS vaccine formulations.