Assessment of the stability and immunogenicity of meningococcal oligosaccharide C-CRM197 conjugate vaccines.

In this stability study, meningococcal C-CRM(197) conjugate vaccines from two different manufacturers that differ in oligosaccharide chain length, number of conjugation sites, conjugation chemistry, manufacturing process and formulation were used. Both the bulk concentrated and final fill preparations were incubated at -20, 4, 23, 37 or 55 degrees C for 5 weeks or subjected to ten cycles of freeze-thawing. The structural stability, hydrodynamic size and integrity of the treated vaccines were monitored by size exclusion chromatography (FPLC-SEC), high performance anion exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD) and fluorescence spectroscopy techniques. The data showed that the structural stability of the oligosaccharide chains and of the protein carrier varied between the two conjugates. The experimental immunogenicity was not severely affected by repeated freeze-thawing, incubation at -20 or 4 degrees C, but one developed conformational changes in the protein carrier when incubated at 23 degrees C or above, although the integrity of the oligosaccharide structure was maintained. This was not associated with any reduction in primary IgG or IgM antibody responses to meningococcal C polysaccharide. In the other conjugate vaccine, exposure to 55 degrees C resulted in the release of a substantial proportion of free saccharide that was accompanied by significant reduction in both IgG and IgM antibody responses to immunisation in the model system. In conclusion, the two meningococcal C-CRM(197) conjugate vaccines were stable when stored at the recommended temperatures, although their structural stability and subsequent immunogenicity were influenced by their conjugation chemistry and formulation.