Peptide mimicry of carbohydrate structures

• Published in: Research in immunology (Paris) Vol. 149; no. 1; pp. 75 - 77
• Main Authors: Phalipon, A., Folgori, A., Arondel, J., Sgaramella, G., Fortugno, P., Cortese, R., Sansonetti, P.J., Felici, F.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1998
• ISSN: 0923-2494
• DOI: 10.1016/S0923-2494(98)80051-5

The main targets of the protective immune response against bacterial infection are the capsular polysaccharide as well as the O-Ag carbohydrate moiety of the LPS. Carbohydrate antigens are T-cell-independent, inducing weak antibody responses associated with the lack of a strong B-cell memory response, and vaccine strategies have thus been mainly focused on the development of either polysaccharide-protein conjugates or anti-idiotype vaccines based on mimicking the carbohydrate structure. The difficult steps of the former approach are the purification of the polysaccharide (especially when starting from LPS, which must be devoid of any residual lipid A-related endotoxic activity) and the loss of immunogenicity of the carbohydrate moiety during coupling to the protein carrier. Carbohydrate synthesis may diminish the problems associated with antigen purification, but nonetheless remains a limited solution due to the overall difficulties of carbohydrate chemistry. The latter strategy, based on the mimicry of carbohydrate antigens by anti-idiotype antibodies, is not a simpler alternative, since obtaining these antibodies is relatively time-consuming, and their use in humans still a matter of debate. Therefore, polysaccharide-protein conjugates remain, despite difficulties, the only viable strategy for human vaccination against bacterial polysaccharidic antigens investigated till now.