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Properties of a Streptococcus suis isolate of serotype 2 and two capsular mutants
S I Salasia1, C Lämmler, G Herrmann
1Institut für Bakteriologie und Immunologie, Justus-Liebig-Universität, Giessen, Germany.
Abstract:
Encapsulation is thought to be a critical virulence factor of Streptococcus suis. In the present study two capsular type 2 mutants of S. suis (M42 and M2) and their S. suis parent strain (89-1591) were further characterized. All three cultures reacted with group D specific antiserum whereas parent strain 89-1591 and mutant M42 but not mutant M2 reacted with specific antiserum against capsular type 2. Both mutants had higher surface hydrophobicity and showed an increased adherence to human epithelial cells and to lung macrophages of rabbits as compared to the parent strain. In phagocytosis experiments with polymorphonuclear leucocytes the encapsulated parent strain was more resistant to phagocytosis than both mutant strains. These findings might help to understand the role of encapsulation of S. suis in the process of infection.
Insights
Encapsulation is a key virulence factor in Streptococcus suis. Loss of capsule in Streptococcus suis mutants increased bacterial adherence and resistance to phagocytosis, aiding infection.
Area of Science:
- Microbiology
- Infectious Diseases
- Bacterial Pathogenesis
Background:
- Encapsulation is a critical virulence factor in Streptococcus suis, a significant swine pathogen.
- Understanding the role of the capsule in S. suis infection is crucial for developing effective control strategies.
Purpose of the Study:
- To characterize capsular type 2 mutants of S. suis and compare their virulence properties to the parent strain.
- To elucidate the impact of encapsulation on S. suis adherence, surface hydrophobicity, and resistance to phagocytosis.
Main Methods:
- Characterization of two capsular type 2 S. suis mutants (M42, M2) and the parent strain (89-1591) using specific antisera.
- Assessment of surface hydrophobicity and adherence to human epithelial cells and rabbit lung macrophages.
- Phagocytosis experiments using polymorphonuclear leukocytes.
Main Results:
- Mutants M42 and M2 exhibited altered capsular type 2 expression compared to the parent strain.
- Both mutants displayed increased surface hydrophobicity and enhanced adherence to host cells and macrophages.
- The encapsulated parent strain was significantly more resistant to phagocytosis than the mutant strains.
Conclusions:
- Loss of encapsulation in S. suis enhances bacterial adherence and reduces resistance to phagocytosis.
- These findings highlight the critical role of encapsulation in S. suis virulence and infection processes.
- Further research into S. suis encapsulation can inform strategies to combat infections caused by this pathogen.