An integrity assay for a meningococcal type B conjugate vaccine

The development of an analytical procedure for the evaluation of a conjugate vaccine's structural wholeness or integrity is described. The principle component of the vaccine was the N-propionylated group B meningococcal polysaccharide (NPr-GBMP) covalently attached to a carrier protein. The goal of the procedure was to determine whether any whole polysaccharide, oligosaccharide, or monosaccharide, from minute to moderate levels, became detached off the conjugate. Free saccharide was isolated from the formulation, which included an aluminum hydroxide adjuvant for analysis. Due to its linkage, the NPr-GBMP did not release sialic acid efficiently with acid hydrolysis to the extent necessary for accurate quantitation. To accomplish depolymerization, the NPr-GBMP was subjected to methanolysis, 3N hydrochloric acid in methanol for 16h at 80 degrees C. The main product of the methanolysis reaction was a de-N-acylated methyl glycoside of sialic acid. N-acetylneuraminic acid oligomers and colominic acid were used to confirm the methanolysis depolymerization efficiency of the alpha(2 --> 8) saccharides; with the treatment all oligomers produced a common methyl glycoside. For this determination anion exchange chromatography and size exclusion chromatography were both interfaced to an integrated pulsed amperometric detector. Sensitivity and linearity were demonstrated to be sufficient for the application with vaccine dose formulations with low total saccharide concentrations.