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Characterization of Streptococcus suis capsular type 2 haemolysin
M G Gottschalk1, S Lacouture, J D Dubreuil
1Groupe de Recherche sur les Maladies Infectieuses du Porc (GREMIP), Faculté de médecine vétérinaire, Université de Montréal, St-Hyacinthe, Québec, Canada.
Abstract:
The production of a haemolysin by Streptococcus suis capsular type 2 was investigated. Human group O erythrocytes were the most susceptible, followed by horse, sheep, cow and pig red blood cells, which exhibited similar susceptibilities; rabbit erythrocytes were the least susceptible. The haemolysin was produced at the end of the exponential growth phase. The toxin described in this paper was purified by affinity chromatography using a thiopropyl-Sepharose 6B column. It is an extracellular protein with a molecular mass of 65 kDa. The haemolysin belongs to the family of toxins known as antigenically related cholesterol-binding cytolytic toxins, since it shares common characteristics with other members of this family, such as sensitivity to oxygen and oxidizing agents, activation by reducing agents, inhibition by low concentrations of cholesterol, formation of transmembrane pores and a 'multihit' mechanism of action. In addition, anti-streptolysin antibodies inhibited the haemolytic activity caused by the S. suis haemolysin. Antibodies against the haemolysin could not be detected in pigs experimentally infected with a haemolytic positive strain of S. suis capsular type 2. To our knowledge, this is the only Lancefield group D Streptococcus producing a haemolysin with these characteristics. The role of this haemolysin in the pathogenesis of S. suis infections remains to be investigated.
Insights
Streptococcus suis capsular type 2 produces a novel 65 kDa haemolysin. This cholesterol-binding cytolytic toxin
Area of Science:
- Microbiology
- Toxicology
- Biochemistry
Background:
- Streptococcus suis is a significant pathogen in pigs and can cause human infections.
- Haemolysins are virulence factors produced by various bacteria, contributing to pathogenesis.
- The characterization of virulence factors in S. suis is crucial for understanding disease mechanisms.
Purpose of the Study:
- To investigate the production and characteristics of a haemolysin from Streptococcus suis capsular type 2.
- To determine the susceptibility of different erythrocytes to the S. suis haemolysin.
- To classify the haemolysin based on its biochemical and functional properties.
Main Methods:
- Investigation of haemolysin production during bacterial growth phases.
- Purification of the haemolysin using affinity chromatography (thiopropyl-Sepharose 6B).
- Characterization of the haemolysin's molecular mass, sensitivity to oxygen/reducing agents, and inhibition by cholesterol.
Main Results:
- A 65 kDa extracellular haemolysin was purified from S. suis capsular type 2.
- Human group O erythrocytes were most susceptible; rabbit erythrocytes were least susceptible.
- The haemolysin shares characteristics with cholesterol-binding cytolytic toxins and is inhibited by anti-streptolysin antibodies.
Conclusions:
- Streptococcus suis capsular type 2 produces a unique haemolysin belonging to the cholesterol-binding cytolytic toxin family.
- The haemolysin's activity was demonstrated against various red blood cells, with differential susceptibility.
- Further investigation is needed to elucidate the role of this haemolysin in S. suis pathogenesis.