Interaction of turkey complement with Escherichia coli isolated from turkeys

Area of Science:

• Veterinary immunology
• Microbiology
• Poultry health

Background:

• The complement system is crucial for innate immunity in turkeys.
• Understanding turkey complement's role against Escherichia coli is vital for poultry health.
• Serum resistance in E. coli poses a challenge to effective treatment.

Purpose of the Study:

• To investigate the role of turkey complement in the bactericidal reaction against Escherichia coli.
• To determine the pathways involved in complement-mediated killing of E. coli in turkeys.
• To assess the impact of antibodies on the susceptibility of E. coli to turkey serum.

Main Methods:

• Utilized serum-sensitive and serum-resistant Escherichia coli strains isolated from turkeys.
• Inactivated complement activity by heating serum and using EDTA chelation.
• Assessed complement activity using hemolytic assays and bactericidal reactions.
• Investigated the alternative complement pathway and the role of antibodies.

Main Results:

• Complement inactivation by heat or EDTA abolished bactericidal activity.
• Turkey serum treated with EGTA and MgCl2 killed serum-sensitive E. coli.
• Both serum-sensitive and serum-resistant E. coli activated the complement system similarly.
• Antibody treatment was necessary to enable complement-mediated killing of specific serum-resistant E. coli strains.

Conclusions:

• Turkey complement plays a significant role in serum bactericidal activity against E. coli.
• Both classical and alternative complement pathways appear to be involved.
• Antibodies are essential for overcoming serum resistance in certain E. coli strains, highlighting their importance in poultry immunity.