PACAP sequence modifications modulate the peptide antimicrobial activity against bacterial pathogens affecting...

Area of Science:

• Aquaculture
• Microbiology
• Biochemistry

Background:

• Aquaculture faces significant economic losses due to fish diseases.
• Antibiotic use for fish infections leads to antimicrobial resistance.
• Aeromonas spp. are problematic fish pathogens known to develop antibiotic resistance.

Purpose of the Study:

• To investigate the direct antimicrobial activity of pituitary adenylate cyclase activating polypeptide (PACAP) and its variants.
• To assess the toxicity of PACAP variants in fish cells.
• To explore PACAP as a potential alternative to antibiotics in aquaculture.

Main Methods:

• Tested five synthetic PACAP variants and the natural variant against Aeromonas salmonicida and Aeromonas hydrophila.
• Evaluated PACAP's antimicrobial activity in different culture broths.
• Assessed the in vitro toxicity of PACAP variants in fish cells.

Main Results:

• All tested PACAP variants exhibited antimicrobial activity against A. salmonicida and A. hydrophila, with activity varying by variant and culture broth.
• PACAP demonstrated a membrane-disruptive mechanism of action, classifying it as a membrane-disruptive antimicrobial peptide (AMP).
• The five PACAP variants showed low in vitro toxicity at concentrations suitable for in vivo applications.

Conclusions:

• PACAP possesses direct antimicrobial properties and acts by disrupting bacterial membranes.
• PACAP variants are effective against key aquaculture pathogens and exhibit low toxicity.
• PACAP presents a viable, potentially antibiotic-free solution for disease management in the aquaculture industry.