Pneumococcal capsule

Most pneumococcal capsules do not activate the alternative pathway, and they also do not seem to interfere with access to the cell wall where... 

Type 3 polysaccharide is one of the first pneumococcal capsule polysaccharides to have its structure determined [184]. It has a simpler structure than type 2 polysaccharide, with only two monosaccharide residues, D-glucopyranose and d-glucopyranose uronic acid, with alternating p-1 - 3 and p-1 - 4 glycosidic linkages in a repeating disaccharide of the following structure [184] ... 

Prevnar is a glycoconjugate heptavalent pneumococcal vaccine for young children made from the polysaccharide capsule of the pneumococcus (20). Although older vaccines made from pneumococcus capsular polysaccharide are available for adults, young children cannot make antibodies to the capsule. By coupling the pneumococcal capsular polysaccharide with a protein carrier, a vaccine was created that will trigger an infant s immune system to produce antibodies. 

Capsules of pneumococci consist largely of a polysaccharide slime, but they contain in addition some protein and small amounts of other substances. The type-specificity and virulence of the pneumococci are due to their capsular polysaccharides (see Chapter VIII). The specificity of reaction for different pneumococcal types is due to variation in the capsular polysaccharide molecules. The antigenic polysaccharides are isolable from the bacteria but are more often prepared from the culture broth into which they are liberated by bacterial autolysis. Though there are more than 70 known types of pneumococci, little is known of the structures of their capsular polysaccharides save that from type III pneumococcus. This is shown to be a linear molecule of D-glucose and D-glucuronic acid units in equal amounts. They are linked alternately so that the molecule may be regarded as a chain of aldobiouronic acid units 131) ... 

Pneumococcal— These polysaccharides control the immunological type specificity of the pneumococci by their presence in the bacterial capsule. Their constituents are D-glucose, D-glucuronic add, aldobionic adds and amino sugars. The proportions of each vary from one type to another and certain constituents may be missing. 

Other pneumococcal strains do not possess a protective capsule and, as a result, are not virulent. Their colonies have a rough surface and so they are called R-bacteria or R-strains. 

---