Porcine beta-defensin 2 displays broad antimicrobial activity against pathogenic intestinal bacteria.
Defensins are small antimicrobial peptides that play an important role in the innate immune system of mammals. Here, we describe the antimicrobial activity of pBD-2, a recently discovered new porcine defensin that is produced in the intestine. A synthetic peptide corresponding to the mature protein showed high antimicrobial activity against a broad range of pathogenic bacteria, while it only showed limited hemolytic activity against porcine red blood cells. Highest activity was observed against Salmonella typhimurium, Listeria monocytogenes and Erysipelothrix rhusiopathiae. pBD-2 (4-8microM) killed these pathogens within 3h. The activity of pBD-2 against S. typhimurium was studied in more detail. At the minimum bactericidal concentration (MBC) of pBD-2, complete killing of S. typhimurium was relatively fast with no viable bacteria left after 90 min. However, antimicrobial activity of pBD-2 was decreased at higher ionic strengths with no residual activity at 150mM NaCl. Transmission electron microscopy of pBD-2 treated S. typhimurium indicated that relatively low doses of pBD-2 caused a retraction of the cytoplasmic membrane, while pBD-2 concentrations close to the MBC led to cytoplasm leakage and complete lysis of bacterial cells. Considering the site of production and the activity, pBD-2 may be an important defense molecule for intestinal health.
Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands. E.Veldhuizen@vet.uu.nl
Edwin J A
EJ
Veldhuizen
Mariëlla
M
Rijnders
Erwin A
EA
Claassen
Albert
A
van Dijk
Henk P
HP
Haagsman
D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000998:Antiviral Agents / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D004305:Dose-Response Relationship, Drug; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D007422:Intestines / Q000187:drug effects* / Q000382:microbiology*; D007700:Kinetics; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D008969:Molecular Sequence Data; D009994:Osmolar Concentration; D019316:Porcine respiratory and reproductive syndrome virus / Q000187:drug effects; D012481:Salmonella Infections, Animal; D012486:Salmonella typhimurium / Q000166:cytology / Q000187:drug effects* / Q000254:growth & development / Q000648:ultrastructure; D016415:Sequence Alignment; D013552:Swine; D023083:beta-Defensins / Q000737:chemistry / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D000998:Antiviral Agents; D023083:beta-Defensins