Vaccine potential of meningococcal group C polysaccharide-tetanus toxoid conjugate.

The antibody response in mice to Neisseria meningitidis (meningococcal) group C polysaccharide could be modified by its conjugation to proteins, i.e. tetanus toxoid. Whereas the pure polysaccharide behaved as a T-independent antigen, the polysaccharide-protein conjugate was clearly a T-dependent antigen, as shown by the pronounced IgG response after the first dose and by the booster effect after the second dose. In comparison, group C polysaccharide-outer membrane protein complexes isolated from the cell-free culture liquid of a meningococcal culture induced only a low level of IgG antibodies. Conjugation did not result in a reversion of tetanus toxoid to toxin. Tetanus toxoid present in the conjugate was as immunogenic as tetanus vaccine.