Factors affecting complement activation by Staphylococcus aureus cell walls, their components, and mutants altered in...

Area of Science:

• Immunology
• Microbiology
• Biochemistry

Background:

• Previous studies indicated Staphylococcus aureus purified cell walls (PCW) are more active in complement consumption than isolated peptidoglycan (PG).
• Teichoic acid (TA), a component of PCW, has now been investigated for its role in complement activation.

Purpose of the Study:

• To investigate the role of teichoic acid (TA) in complement consumption by Staphylococcus aureus.
• To understand the influence of physical and chemical treatments on the complement-activating properties of bacterial cell wall components.

Main Methods:

• Complement consumption assays were performed using isolated peptidoglycan (PG), teichoic acid (TA), and purified cell walls (PCW) from Staphylococcus aureus.
• Various treatments including sonication, lysostaphin solubilization, formamide extraction, and periodate extraction were applied to bacterial components.
• Complement consumption by whole Staphylococcus aureus strains, including TA-deficient mutants, was compared.

Main Results:

• Isolated TA activated complement, and sonication enhanced PG activity but not PCW or TA activity.
• Sonication likely enhanced PG activity by increasing surface area, while lysostaphin treatment decreased activity.
• TA-deficient mutants showed similar complement consumption to parent strains, indicating TA is not essential in whole organisms.

Conclusions:

• While TA can activate complement, it is not essential for complement consumption by whole Staphylococcus aureus.
• Physical factors like particle dispersion and chemical composition significantly impact complement activation by bacterial cell wall components.
• Both cell surface components and extracellularly released material contribute to complement activation by staphylococci.