Serum opacity factor is a major fibronectin-binding protein and a virulence determinant of M type 2 Streptococcus pyogenes
| Autor: | Jenny L. Thacker, James B. Dale, Herbert C. Chiang, Yi Li, David L. Hasty, Harry S. Courtney |
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| Rok vydání: | 1999 |
| Předmět: |
Time Factors
Cell Survival Streptococcus pyogenes Blotting Western Molecular Sequence Data Virulence Biology medicine.disease_cause Microbiology Group A Virulence factor Conserved sequence Mice medicine Animals Amino Acid Sequence Molecular Biology DNA Primers Models Genetic Sequence Homology Amino Acid biology.organism_classification Fibronectins Complementation Blotting Southern Fibronectin binding Female Carrier Proteins Streptococcus dysgalactiae Peptide Hydrolases Protein Binding |
| Zdroj: | Molecular Microbiology. 32:89-98 |
| ISSN: | 1365-2958 0950-382X |
| Popis: | Serum opacity factor (SOF) is a fibronectin-binding protein of group A streptococci that opacifies mammalian sera and is expressed by some strains that cause impetigo, pharyngitis and acute glomerulonephritis. Although SOF is expressed by approximately 35% of known serotypes, its role in the pathogenesis of group A streptococcal infections has not been previously investigated. The sof genes from M types 2, 28 and 49 Streptococcus pyogenes were cloned, sequenced, and their deduced amino acid sequences were compared. The gene for FnBA, a fibronectin-binding protein from Streptococcus dysgalactiae, was also cloned and found to express an opacity factor. The leader sequences, the fibronectin-binding domains, and the membrane anchor regions of these proteins were highly conserved. Short spans of conserved sequences were interspersed throughout the remaining parts of the proteins. The sof2 gene was insertionally inactivated in an M type 2 S. pyogenes strain, T2MR. The resultant SOF-negative mutant (YL3) did not express SOF or opacify serum, and exhibited a 71% reduction in binding fibronectin. Complementation of the SOF-negative defect with sof28 in the recombinant strain YL3(pNZ28) fully restored fibronectin-binding activity and the ability to opacify serum. To determine whether sof plays a role in virulence, mice were challenged intraperitoneally with these strains. None of the 10 mice infected with YL3(pNZ28) survived and only 1 out of 15 mice challenged with T2MR survived, whereas 12 out of 15 mice infected with YL3 survived. These data clearly indicate that SOF is a virulence factor, and they provide the first direct evidence that a fibronectin-binding protein contributes to the pathogenesis of group A streptococcal infections in vivo. |
| Databáze: | OpenAIRE |
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