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Immunochemical characterization of the mucoid exopolysaccharide of Pseudomonas aeruginosa
Abstract:
Alginic acid-like mucoid exopolysaccharide was isolated from three strains of Pseudomonas aeruginosa obtained from the sputa of patients with cystic fibrosis. Purified mucoid antigens were greater than 99% uronic acid. With a hemagglutination assay, antibody responses to the mucoid exopolysaccharide were documented after immunization of rabbits with either whole mucoid organisms or purified mucoid exopolysaccharide. The mucoid antigen from one strain (no. 2192) was composed predominantly of a single serologic epitope shared among 40 alginate exopolysaccharides from different clinical isolates. The mucoid exopolysaccharide from the other two strains (nos. 1 and 258) had a serotype-specific determinant in addition to the common epitope. Analyses of antibody in sera from normal adults, children, and patients with cystic fibrosis culture-positive and culture-negative for mucoid P. aeruginosa showed a highly significant (P less than 0.001) association between increased hemagglutination titers and positive cultures for mucoid P. aeruginosa.
Insights
Antibodies to Pseudomonas aeruginosa mucoid exopolysaccharide are common in cystic fibrosis patients. This finding links immune response to mucoid P. aeruginosa infections in cystic fibrosis.
Area of Science:
- Microbiology
- Immunology
- Biochemistry
Background:
- Pseudomonas aeruginosa is a major pathogen in cystic fibrosis (CF) patients.
- Mucoid strains of P. aeruginosa produce alginate exopolysaccharides, contributing to chronic infections.
- Understanding the immune response to these mucoid antigens is crucial for CF management.
Purpose of the Study:
- To isolate and characterize mucoid exopolysaccharides from P. aeruginosa strains found in CF patients.
- To investigate antibody responses to these mucoid antigens in experimental models and human sera.
- To determine the association between antibody titers and the presence of mucoid P. aeruginosa in CF patients.
Main Methods:
- Isolation and purification of alginic acid-like mucoid exopolysaccharides.
- Hemagglutination assays to detect antibody responses.
- Serological analysis of mucoid antigens to identify epitopes.
- Analysis of human sera from CF patients and controls.
Main Results:
- Mucoid exopolysaccharides were primarily composed of uronic acid.
- Antibodies to mucoid exopolysaccharides were detected in rabbits after immunization.
- A common serologic epitope was identified in mucoid antigens from various clinical isolates.
- Increased hemagglutination titers showed a significant association with positive cultures for mucoid P. aeruginosa in CF patients.
Conclusions:
- Mucoid P. aeruginosa exopolysaccharides contain shared and specific antigenic determinants.
- Immune responses to mucoid P. aeruginosa are significantly associated with active infection in cystic fibrosis.
- These findings highlight the importance of targeting mucoid P. aeruginosa in CF therapeutic strategies.