Characteristics of two types of meningococcal group C polysaccharide conjugates using tetanus toxoid as carrier protein.

Effective meningococcal vaccines have to induce protection against groups A, B, C, W-135 and Y meningocci. Polysaccharides are the most effective vaccine candidates against groups A, C, W-135 and Y meningococci. The vaccine potential of polysaccharides is enhanced by conjugating the polysaccharides to carrier proteins. This paper describes the preparation and immunological characterization of two types of group C polysaccharide - tetanus toxoid conjugate. Both types of conjugate were produced by different procedures. Procedure i. depends on cross-linking of both components with N-ethyl-N'-(3-dimethylaminopropyl) carbodimide. Procedure ii. is a more monofunctional way of conjugating partially depolymerized polysaccharide with tetanus toxoid by reductive amination. The antigenic activity of the tetanus toxoid component of the conjugates containing this carrier protein was studied in ELISA and showed differences between the conjugate preparations. The immunogenic activity of all conjugate preparations was tested in mice. All conjugates produced IgG antibodies to the polysaccharide component, although the booster effects of procedure ii. conjugates were less pronounced than those of procedure i. conjugates. The immunogenic activity of the tetanus toxoid component of the various conjugate preparations correlated rather well with their antigenic activities as measured in ELISA.