Polisacáridos capsulares como vacunas antibacterianas / Capsular polysaccharide as anti-bacterial vaccines

RESUMO

Many bacterial pathogens are encapsulated, and these capsules are known or thought to be important in their virulence. Capsular polysaccharides are known to be good immunogens, and the first multivalent vaccines based on the capsular polysaccharides of Streptococcus pneumoniae was developed in 1945. However, it was not until recent renewed interst in the prophylaxis of bacterial disease that these materials were reconsidered as vaccine candidates. They offer the advantege of being defined molecular species that can be readily isolated, are non-toxi, and with few exceptions, inmunogenic. Several problems are still associated with polkysaccharide vaccines a) the poor immunogenicity of all the polysaccharides in infantes, and b) the poor immunogenicity of all the polusaccharides in infants. and b) the poor immunogenicity of a few polusaccharides in al humans. New strategies have been developed in order to overcome these problems, such as chemical modification of the polysaccharides and conjugation of the polysaccharides to carrier proteins. The purpose of this paper is to describe briefly the strutural characteristics of the capsular polysaccharides and their relation to immunogenicity, and be development of vaccines based on capsular polysaccharides with examples of those currently being used and those having future potential use. As well, some of the strategies directed towards producing plysaccharide-protein conjugates will be discussed