Conjugation of meningococcal lipopolysaccharide R-type oligosaccharides to tetanus toxoid as route to a potential vaccine against group B Neisseria meningitidis.

Oligosaccharides were obtained by the mild acid hydrolysis of the lipopolysaccharides from a number of different strains of Neisseria meningitidis, serotypes L2, L3, L4, L5, and L10. The dephosphorylated oligosaccharides were conjugated to tetanus toxoid as their 2-(4-isothiocyanatophenyl)-ethylamine derivatives, which resulted in the incorporation of from 18 to 38 oligosaccharides per molecule of tetanus toxoid. When injected in rabbits, the conjugates produced oligosaccharide-specific antibodies which were predominantly serologically specific but which also exhibited some cross-reactivity. These serological results can be attributed to regions of structural dissimilarity and similarity within the oligosaccharides. The oligosaccharide-specific antibodies were also lipopolysaccharide serotype specific, thus indicating that the oligosaccharides are the determinants associated with this serotype specificity. Consistent with the serological results, the conjugate antisera were bactericidal for the homologous serotype meningococcal organisms and in some cases for heterologous serotype organisms.