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Immunological characterization of an exopolysaccharide from the Staphylococcus aureus strain Smith diffuse
T E West1, B A Lewis, M A Apicella
1Division of Infectious Diseases, State University of New York, Buffalo 14215.
Abstract:
Exopolysaccharides (EXPs) of Staphylococcus aureus are associated with virulence in animal models. An EXP from the S. aureus strain Smith diffuse was previously detected in 64.3% of S. aureus clinical isolates. EXP was isolated from culture supernatants of this strain after DNAase, RNAase, phosphodiesterase I and lysostaphin treatment, and was further purified by cation-exchange and molecular-sieve chromatography. Isoelectric focusing revealed a pI of 3.6 for the EXP while the pI of teichoic acid was less than 2.7. Crossed immunoelectrophoresis with homologous Smith diffuse antisera indicated that the EXP contained two immunological components. A major precipitin line persisted after the antisera had been absorbed with the non-EXP-producing variant strain, Smith compact, while the second component was removed. Tandem immunoelectrophoresis also demonstrated that the EXP was distinct from teichoic acid. The EXP contained 2-amino-2-deoxyglucuronic acid, glucose, mannose and galactose. No fatty acids or nucleic acids were present and total protein content was less than 2%. Teichoic acid could not be demonstrated in the EXP, thus further substantiating the immunological studies. S. aureus EXP isolated by the present method can be used for further serological and virulence studies.
Insights
Staphylococcus aureus exopolysaccharides (EXPs) were isolated and purified, showing distinct immunological properties from teichoic acid. These findings aid further studies on bacterial virulence and serology.
Area of Science:
- Microbiology
- Immunology
- Biochemistry
Background:
- Staphylococcus aureus exopolysaccharides (EXPs) are linked to virulence in animal models.
- An EXP from S. aureus strain Smith diffuse is found in over 64% of clinical isolates.
Purpose of the Study:
- To isolate and characterize exopolysaccharides (EXPs) from Staphylococcus aureus.
- To differentiate EXP from teichoic acid using immunological and biochemical methods.
- To establish a method for obtaining S. aureus EXP for further research.
Main Methods:
- EXP isolation from culture supernatants using enzymatic and chemical treatments.
- Purification via cation-exchange and molecular-sieve chromatography.
- Characterization using isoelectric focusing, crossed immunoelectrophoresis, and tandem immunoelectrophoresis.
Main Results:
- The isolated EXP exhibited a pI of 3.6, distinct from teichoic acid (pI < 2.7).
- Immunoelectrophoresis confirmed EXP contains two components, one unique and not teichoic acid.
- EXP composition includes 2-amino-2-deoxyglucuronic acid, glucose, mannose, and galactose, with minimal protein and no fatty acids or nucleic acids.
Conclusions:
- The study successfully isolated and purified Staphylococcus aureus EXP.
- Immunological and biochemical analyses confirm EXP is distinct from teichoic acid.
- The developed method provides a basis for future serological and virulence studies of S. aureus EXP.