Characterization of polyribosylribitol phosphate by high performance molecular exclusion chromatography with ultraviolet detection

Haemophilus influenzae type b is an important human pathogen causing several invasive diseases in children under five years of age, against which glycoconjugated vaccines based on polyribosylribitol phosphate have been licensed. Quimi-Hib® is the first and only vaccine against this pathogen using the polysaccharide obtained by chemical synthesis. The Active Pharmaceutical Ingredient is produced by the Center for Genetic Engineering and Biotechnology and is obtained from its conjugation to tetanus toxoid. In the present report, a characterization of polyribosylribitol phosphate was performed using the high performance molecular exclusion chromatography technique with ultraviolet detection at 215 nm. Three batches were evaluated in the study and the elution profile was determined on a SuperdexTM 75 10/300 GL Increase column with a purity percent of 77.42 ± 8.97 and an average molar mass of 7381 Da ± 210.93. The main impurity present in polyribosylribitol phosphate is dimethyl sulfoxide, the solvent used in the activation reaction with the N-hydroxysuccinimidyl ester of β-maleimidopropionic acid. The polyribosylribitol phosphate was purified by filtration with a 2000 Da Amicon Ultra-15 to 99.1% purity and conjugated to tetanus toxoid. The yield of the conjugation reaction with the purified polysaccharide was 30.0% ± 1.77% which shows no significant difference with the control which was 33.7% ± 3.57% demonstrating that dimethyl sulfoxide does not affect the performance of the conjugation reaction.