Process development and immunogenicity studies on a serogroup 'X' Meningococcal polysaccharide conjugate vaccine

Meningococcal group X (MenX) is responsible for recent outbreaks of meningitis reported in sub-Saharan region of Africa. Although protective vaccines are available for meningitis, they are not effective against MenX. An efficacious, monovalent conjugate vaccine was designed against MenX and a fed-batch fermentation process was developed. The MenX polysaccharide (PS) was purified and yield estimated to be 15-fold higher than the reported elsewhere. Structure of MenX polysaccharide was confirmed by H-1, C-13 NMR spectroscopy analysis. Molecular weight of PS was found to be 310 kDa using HPLC-SEC coupled to refractive index (RI) detector. The MenX- Tetanus toxoid (TT) monovalent conjugate proved to be highly immunogenic in mice, and the bactericidal titers of MenX-TT conjugate were 10-fold higher than native PS. Increasing the dose of MenX-TT conjugate from 0.5 mu g to 1.0 mu g induced an 8-fold higher antibody titer as well as serum bactericidal titer. The current work suggests that the MenX-TT conjugate is a candidate vaccine against meningitis caused by Meningococcal group X strains. (C) 2013 The International Alliance for Biological Standardization. Published by Elsevier Ltd. All rights reserved.