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Antimicrobial Peptides Produced by Selective Pressure Incorporation of Non-canonical Amino Acids
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Antimicrobial Peptides Produced by Selective Pressure Incorporation of Non-canonical Amino Acids

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A peptide derived from human bactericidal/permeability-increasing protein (BPI) exerts bactericidal activity against

Annapoorani Chockalingam1, Cindy E McKinney, Manuela Rinaldi

  • 1Department of Dairy and Animal Science, Pennsylvania State University, University Park, PA 16802, USA.

Veterinary Microbiology
|June 15, 2007
PubMed

Insights

A novel synthetic peptide derived from human Bactericidal/permeability-increasing protein (BPI) shows antimicrobial activity against Gram-negative bacteria causing bovine mastitis. This peptide effectively neutralizes lipopolysaccharide (LPS), offering potential for new cattle infection treatments.

Area of Science:

  • Veterinary Medicine
  • Microbiology
  • Biochemistry

Background:

  • Gram-negative bacteria cause significant bovine mastitis cases, leading to severe systemic inflammation due to lipopolysaccharide (LPS).
  • Current treatments for Gram-negative infections and associated inflammation in cattle are suboptimal.
  • Bactericidal/permeability-increasing protein (BPI) is a human neutrophil protein with known antimicrobial and LPS-neutralizing capabilities.

Purpose of the Study:

  • To assess the antimicrobial efficacy of a synthetic peptide derived from human BPI against Gram-negative bacteria implicated in bovine mastitis.
  • To evaluate the peptide's ability to neutralize LPS and its activity in the presence of bovine serum and milk.

Main Methods:

  • A hybrid synthetic peptide combining bactericidal (amino acids 90-99) and LPS-neutralizing (amino acids 148-161) regions of human BPI was synthesized.
  • Broth microdilution assays were used to determine the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) against clinical isolates.
  • Functional assays assessed LPS neutralization and peptide activity in serum and milk.

Main Results:

  • The peptide exhibited antimicrobial activity against Escherichia coli, Klebsiella pneumoniae, Enterobacter spp., and Pseudomonas aeruginosa, with MICs ranging from 16-256 µg/ml.
  • MBCs were comparable to MICs, indicating bactericidal action, though no effect was observed against Serratia marcescens.
  • The peptide retained activity in serum but was significantly impaired in milk, yet it completely neutralized LPS.

Conclusions:

  • The BPI-derived peptide demonstrates significant antimicrobial and LPS-neutralizing properties against key Gram-negative mastitis pathogens.
  • Its efficacy in serum but not milk suggests potential challenges for intramammary application, warranting further investigation.
  • These findings support the exploration of BPI-based therapeutics for treating Gram-negative infections in cattle.

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