Interaction between the Staphylococcus aureus extracellular adherence protein Eap and its subdomains with platelets

Area of Science:

• Microbiology
• Immunology
• Biochemistry

Background:

• Staphylococcus aureus bacteremia poses a high mortality risk, often leading to sepsis and infective endocarditis.
• Numerous S. aureus virulence factors and adhesins are known to interact with human platelets, influencing infection severity.
• Extracellular adherence protein (Eap) is a critical S. aureus virulence factor that interacts with various human circulatory cells.

Purpose of the Study:

• To investigate the specific interaction between S. aureus Eap subdomain D3D4 and human platelets.
• To elucidate the role of Eap D3D4 in platelet activation.
• To develop and validate novel methods for screening S. aureus virulence factors and adhesins for platelet interactions.

Main Methods:

• Utilized amine-reactive fluorescent N-hydroxysuccinimidyl (NHS)-ester dyes for detecting Eap-platelet interactions.
• Employed direct detection with anti-histidine (His-tag) antibodies to identify N-terminal His6-tagged Eap D3D4.
• Applied site-directed immobilization of His6-Eap D3D4 on Ni-NTA functionalized microbead arrays for real-time calcium release assays to visualize platelet activation.

Main Results:

• Demonstrated that the Eap D3D4 subdomain specifically interacts with and rapidly activates human platelets.
• Successfully visualized real-time platelet activation triggered by immobilized Eap D3D4.
• Validated the efficacy of the developed bacteriomimetic microbead array system for platelet activation assays.

Conclusions:

• The S. aureus Eap D3D4 subdomain is a direct activator of human platelets.
• The developed methods provide an accessible platform for screening bacterial virulence factors and adhesins for their effects on platelets.
• Understanding these interactions can inform strategies for combating S. aureus infections.