Biochemical, genetic, and serological characterization of two capsule subtypes among Streptococcus pneumoniae Serotype 20 strains: discovery of a new pneumococcal serotype.

ABSTRACT: The bacterial pathogen Streptococcus pneumoniae expresses one of over 90 structurally distinct polysaccharide (PS) capsule serotypes. Prior PS structural analyses of the vaccine-associated serotype 20 do not agree with reports describing the genes that mediate capsule synthesis. Furthermore, using immunized human sera-based assays, serological differences were recently noted among strains typed as serotype 20. We examined the capsule structures of two serologically dissimilar serotype 20 strains, 20α and 20β, by extensive biochemical analysis. 20α PS was composed of the previously described serotype 20 hexasaccharide repeat unit, whereas the 20β PS was composed of a novel heptasaccharide repeat unit containing an extra branching α-glucose residue. Genetic analysis of the subtypes revealed

SUBMITTER: Calix JJ 

PROVIDER: S-EPMC3431705 | biostudies-literature | 2012 Aug

REPOSITORIES: biostudies-literature