A peptide derived from human bactericidal/permeability-increasing protein (BPI) exerts bactericidal activity against Gram-negative bacterial isolates obtained from clinical cases of bovine mastitis.
Gram-negative bacteria are responsible for approximately one-third of the clinical cases of bovine mastitis and can elicit a life-threatening, systemic inflammatory response. Lipopolysaccharide (LPS) is a membrane component of Gram-negative bacteria and is largely responsible for evoking the inflammatory response. Antibiotic and anti-inflammatory therapy for treating Gram-negative infections remains suboptimal. Bactericidal/permeability-increasing protein (BPI) is a neutrophil-derived protein with antimicrobial and LPS-neutralizing properties. Select peptide derivatives of BPI are reported to retain these properties. The objective of this study was to evaluate the antimicrobial activity of a human BPI-derived synthetic peptide against clinical bovine mastitis isolates of Gram-negative bacteria. A hybrid peptide was synthesized corresponding to two regions of human BPI (amino acids 90-99 and 148-161), the former of which has bactericidal activity and the latter of which has LPS-neutralizing activity. The minimum inhibitory (MIC) and bactericidal (MBC) concentrations of this peptide against various genera of bacteria were determined using a broth microdilution assay. The MIC's were determined to be: 16-64 microg/ml against Escherichia coli; 32-128 microg/ml against Klebsiella pneumoniae and Enterobacter spp.; and 64-256 microg/ml against Pseudomonas aeruginosa. The MBC's were equivalent to or 1-fold greater than corresponding MIC's. The peptide had no growth inhibitory effect on Serratia marcescens. The antimicrobial activity of the peptide was retained in the presence of serum, but severely impaired in milk. Further functional evaluation of the peptide demonstrated its ability to completely neutralize LPS. Together, these data support additional investigations into the therapeutic application of BPI to the treatment of Gram-negative infections in cattle.
Chockalingam
Annapoorani
A
Department of Dairy and Animal Science, Pennsylvania State University, University Park, PA 16802, USA.
McKinney
Cindy E
CE
Rinaldi
Manuela
M
Zarlenga
Dante S
DS
Bannerman
Douglas D
DD
D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology*; D001798:Blood Proteins / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology; D002413:Cations, Divalent; D002417:Cattle; D004492:Edetic Acid / Q000737:chemistry; D005260:Female; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D016905:Gram-Negative Bacterial Infections / Q000097:blood / Q000382:microbiology / Q000662:veterinary*; D006801:Humans; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D008414:Mastitis, Bovine / Q000097:blood / Q000382:microbiology*; D008565:Membrane Proteins / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D008892:Milk / Q000382:microbiology; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D001798:Blood Proteins; D002413:Cations, Divalent; D008070:Lipopolysaccharides; D008565:Membrane Proteins; D010446:Peptide Fragments; C021623:bactericidal permeability increasing protein; D004492:Edetic Acid; D008274:Magnesium; D002118:Calcium