Identification of duck liver-expressed antimicrobial peptide 2 and characterization of its bactericidal activity

  • Hong, Yeojin (Department of Animal Science and Technology, Chung-Ang University) ;
  • Truong, Anh Duc (Department of Animal Science and Technology, Chung-Ang University) ;
  • Lee, Janggeun (Department of Animal Science and Technology, Chung-Ang University) ;
  • Lee, Kyungbaek (Department of Animal Science and Technology, Chung-Ang University) ;
  • Kim, Geun-Bae (Department of Animal Science and Technology, Chung-Ang University) ;
  • Heo, Kang-Nyeong (Poultry Research Institute, National Institute of Animal Science, RDA) ;
  • Lillehoj, Hyun S. (Animal Biosciences and Biotechnology Laboratory, Agricultural Research Services, United States Department of Agriculture) ;
  • Hong, Yeong Ho (Department of Animal Science and Technology, Chung-Ang University)
  • Received : 2018.07.28
  • Accepted : 2018.10.26
  • Published : 2019.07.01


Objective: This study was conducted to identify duck liver-expressed antimicrobial peptide 2 (LEAP-2) and demonstrate its antimicrobial activity against various pathogens. Methods: Tissue samples were collected from 6 to 8-week-old Pekin ducks (Anas platyrhynchos domesticus), total RNA was extracted, and cDNA was synthesized. To confirm the duck LEAP-2 transcript expression levels, quantitative real-time polymerase chain reaction was conducted. Two kinds of peptides (a linear peptide and a disulfide-type peptide) were synthesized to compare the antimicrobial activity. Then, antimicrobial activity assay and fluorescence microscopic analysis were conducted to demonstrate duck LEAP-2 bactericidal activity. Results: The duck LEAP-2 peptide sequence showed high identity with those of other avian species (>85%), as well as more than 55% of identity with mammalian sequences. LEAP-2 mRNA was highly expressed in the liver with duodenum next, and then followed by lung, spleen, bursa and jejunum and was the lowest in the muscle. Both of LEAP-2 peptides efficiently killed bacteria, although the disulfide-type LEAP-2 showed more powerful bactericidal activity. Also, gram-positive bacteria was more susceptible to duck LEAP-2 than gram-negative bacteria. Using microscopy, we confirmed that LEAP-2 peptides could kill bacteria by disrupting the bacterial cell envelope. Conclusion: Duck LEAP-2 showed its antimicrobial activity against both gram-positive and gram-negative bacteria. Disulfide bonds were important for the powerful killing effect by disrupting the bacterial cell envelope. Therefore, duck LEAP-2 can be used for effective antibiotics alternatives.


Supported by : National Research Foundation, NIFA


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