The capsular polysaccharide of Streptococcus pneumoniae represents an important virulence factor and protects against phagocytosis. In this study the amount of capsular polysaccharide present on the bacterial surface during the infection process was illustrated by electron microscopic studies. After infection of A549 cells (type II pneumocytes) and HEp-2 epithelial cells a modified fixation met...

In this study we report the isolation and purification of the capsular polysaccharide elaborated by Staphylococcus aureus SA1 mucoid. The capsule was isolated from bacterial extracts and culture supernatants by a series of ethanol precipitations and enzyme digestions, followed by ion-exchange chromatography. Teichoic acid contamination was eliminated by oxidation with sodium metaperiodate, and ...

Jacob and Monod have proposed that regulator genes may control the syntheses of several related enzymes in Escherichia coli K12.1 The present paper provides evidence for a regulator gene (designated R1)2 which controls capsular polysaccharide synthesis in E. coli K12. Certain mutants of E. coli produce large mucoid colonies which are characterized by overproduction of polysaccharide. The polysa...

Streptococcus pneumoniae undergoes spontaneous phase variation between a transparent and an opaque colony phenotype, the latter being more virulent in a murine model of sepsis. Opaque pneumococci have previously been shown to express lower amounts of C polysaccharide (cell wall teichoic acid) and in this study were shown to have a higher content of capsular polysaccharide by immunoelectron micr...

Neisseria meningitidis (meningococcus) is a Gram-negative human pathogen that causes meningococcal diseases, such as meningococcal meningitis and meningococcal septicemia. Based on the surface capsular oligosaccharides of the organism, 13 serogroups of N. meningitidis have been identified, among which A, B, C, Y, and W135 are the major pathogenic strains. Serogroup A is the pathogen most often ...

Streptococcus suis is a major swine pathogen and important zoonotic agent causing mainly septicemia and meningitis. However, the mechanisms involved in host innate and adaptive immune responses toward S. suis as well as the mechanisms used by S. suis to subvert these responses are unknown. Here, and for the first time, the ability of S. suis to interact with bone marrow-derived swine dendritic ...

The first demonstration of transformation (Griffith, 1928) was concerned with type-specific capsular polysaccharides of pneumococci. Such transformations of capsular types usually are accompanied by a change in colony type since most investigators have studied transformation of R cells which produce little or no capsular material. Coiacomitant transformation of capsular and colony type has been...

Polysaccharide capsules are important virulence factors for many microbial pathogens including the opportunistic fungus Cryptococcus neoformans. In the present study, we demonstrate an unusual role for a secreted lactonohydrolase of C. neoformans, LHC1 in capsular higher order structure. Analysis of extracted capsular polysaccharide from wild-type and lhc1Δ strains by dynamic and static light s...

Sialylation of bacterial capsules has been proposed as an important virulence factor for several species of encapsulated pathogens, including group B Streptococcus. We have constructed a transposon mutant strain of type III group B Streptococcus that expresses a capsular polysaccharide differing from the wild type only in that the mutant strain's capsule lacks sialic acid. The mutant polysaccha...