Polysaccharide-protein conjugates immunogenicity

Schneerson R, Barrera O, Sutton A, Robbins JB. Preparation, characterization, and immunogenicity of Haemophilus influenzae type b polysaccharide-protein conjugates. J Exp Med 1980 152 361-376. 

In experimental studies on the formation of antibodies to a hapten-protein conjugate, it appears that the more immunogenic the protein, the better the response. Although proteins are usually the most efficient carriers, polypeptides, polysaccharides, lipid membranes, or even polynucleotides may be sufficient to impart im-munogenicity. In recent years, direct conjugation of simple chemicals to structural elements of cell membranes (especially of monocytes and macrophages) has been thought to play an important role in the induction of sensitization (de Weck 1975 Shearer 1975). The protein carrier or cell membrane structure of the host may contribute to the specificity of the response (partial autoimmunity). 

S. pneumoniae has more than 80 sero-types. The current polysaccharide vaccine consists of 23 serotypes and covers about 87% of all pneumococcal diseases in the United States. Current vaccine development is based on conjugate technology and concentrates on the most prevalent 7—9 serotypes. Three multivalent vaccine candidates are in clinical trials. All are based on conjugating the polysaccharide to a T-dependent protein carrier. The results of phase I and II trials in infants have demonstrated the safety and immunogenicity (56—58) of these vaccines. Phase III trials to demonstrate efficacy against systematic diseases and otitis media are in progress and final approval of this vaccine for infant immunization will be by the year 2000. 

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