Innate immune cocktail partially protects broilers against cellulitis and septicemia

Area of Science:

• Veterinary Medicine
• Immunology
• Microbiology

Background:

• Antimicrobial/host defense peptides (A/HDP) are natural compounds with broad-spectrum antimicrobial and immune-stimulating properties.
• Gamma-amino butyric acid (GABA), a neurotransmitter, also exhibits wound-healing capabilities.
• Escherichia coli infections pose a significant economic threat to the poultry industry.

Purpose of the Study:

• To develop a therapeutic cocktail of A/HDP and GABA to protect broilers against E. coli infection.
• To evaluate the efficacy of the cocktail based on survival rates, clinical signs, and pathological outcomes.
• To investigate the immunomodulatory effects of the cocktail on avian cells.

Main Methods:

• A cocktail of six A/HDPs with or without GABA was administered to 3-week-old broilers via subcutaneous or intramuscular routes.
• Birds were challenged with a field isolate of E. coli (serogroup O2) 24 hours post-injection.
• Clinical, pathological, and bacteriological assessments were conducted over 5-6 days, along with gene expression analysis.

Main Results:

• Subcutaneous injection of A/HDP plus GABA significantly increased survival rates and reduced bacteremia compared to controls.
• Intramuscular administration showed a trend towards protection against mortality but did not significantly reduce bacteremia or cellulitis lesion size.
• The cocktail induced temporal expression of pro-inflammatory cytokines in avian cells, suggesting immunomodulatory effects.

Conclusions:

• The route of administration is critical for the efficacy of the A/HDP plus GABA cocktail in broilers.
• Subcutaneous administration demonstrates potential for protecting against E. coli-related mortality.
• The cocktail's ability to induce pro-inflammatory cytokines may contribute to its protective effects against E. coli infection.