Streptococcus suis and group B Streptococcus differ in their interactions with murine macrophages

Area of Science:

• Bacteriology
• Immunology
• Cell Biology

Background:

• Streptococcus suis type 2 and group B Streptococcus type III (GBS) are significant encapsulated bacterial pathogens responsible for meningitis.
• Understanding their interaction with host immune cells is crucial for developing effective treatments.

Purpose of the Study:

• To quantitatively compare the phagocytosis and intracellular survival of S. suis type 2 and GBS type III by murine macrophages under non-opsonic conditions.
• To investigate the role of the capsule in the interaction of these pathogens with macrophages.

Main Methods:

• Quantitative comparison of uptake and intracellular survival of encapsulated and unencapsulated strains of S. suis type 2 and GBS type III with murine macrophages.
• Utilized non-opsonic conditions to assess inherent bacterial-macrophage interactions.

Main Results:

• Encapsulated S. suis type 2 was poorly phagocytosed, while its unencapsulated mutant showed increased uptake.
• Both encapsulated and unencapsulated GBS type III strains were phagocytosed in large numbers.
• Intracellular survival was significantly higher for both GBS strains compared to S. suis strains.
• The capsule played a differential role as an antiphagocytic factor between the two species.

Conclusions:

• The interaction mechanisms of GBS type III and S. suis type 2 with murine macrophages differ significantly.
• The bacterial capsule serves as an antiphagocytic factor, but its effectiveness varies between S. suis and GBS.