O-phthalaldehyde based quantification of polysaccharide modification in conjugate vaccines

Area of Science:

• Vaccine Development
• Immunology
• Analytical Chemistry

Background:

• Infant vaccines require T-cell dependent responses, which polysaccharide-based vaccines alone cannot provide.
• Glycoconjugate vaccines, formed by linking polysaccharides to carrier proteins, elicit T-cell dependent immunity and are vital for infant immunization.
• Current manufacturing methods like reductive amination and CDAP-based conjugation activate polysaccharide hydroxyl groups, but quantifying CDAP-activated groups is challenging.

Purpose of the Study:

• To develop and validate a novel method for quantifying cyanate ester groups on polysaccharides activated by CDAP chemistry.
• To enable accurate assessment of polysaccharide activation extent, crucial for conjugate vaccine quality control.

Main Methods:

• A novel strategy involving O-phthalaldehyde (OPA) derivatization was employed.
• Size-exclusion chromatography (SEC) coupled with high-performance liquid chromatography (HPLC) was used for separation.
• UV detection was utilized to quantify the derivatized cyanate ester groups.

Main Results:

• The developed method successfully quantifies cyanate ester groups on activated polysaccharides.
• This technique allows for the direct assessment of polysaccharide activation/modification extent.
• Residual activated groups in purified conjugates can also be determined.

Conclusions:

• The OPA derivatization followed by SEC-HPLC-UV is a reliable method for quantifying cyanate ester groups generated by CDAP chemistry.
• This method is essential for monitoring and controlling the quality of glycoconjugate vaccines manufactured using CDAP chemistry.
• Accurate quantification ensures optimal conjugate vaccine stability and immunogenicity for infant vaccination.