N-propionylation

Serogroup B Neisseria meningitidis remains a major world health problem and currently there is no fully efficacious vaccine available. The poor immunogenicity of the group B meningococcal polysaccharide both in adults and infants prevents the formulation of a comprehensive polysaccharide-based vaccine (1). Although, as discussed in Chapter 4 , conjugation technology can overcome the limitation of the poor immunogenicity of most capsular polysaccharides, the serogroup B meningococcal polysaccharide when conjugated to a protein carrier still failed to give a significant immune response (2,3). This phenomenon is probably attributed to the molecular mimicry between the polysaccharide and human-tissue antigens. As shown in Fig. 1, the serogroup B polysaccharide is a homopolymer of α(2-8)-linked sialic-acid residues (4) and similar structures have also been identified in the humantissue antigens, from short trimeric fragments found in mammalian gangliosides (5) to long decameric fragments observed in the glycoproteins of neural-cell adhesion molecules (N-CAMs) (6). Fig. 1. Chemical structure of GBMP.