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

• Published in: Asian-australasian journal of animal sciences Vol. 32; no. 7; pp. 1052 - 1061
• Main Authors: Hong, Yeojin, Truong, Anh Duc, Lee, Janggeun, Lee, Kyungbaek, Kim, Geun-Bae, Heo, Kang-Nyeong, Lillehoj, Hyun S, Hong, Yeong Ho
• Format: Journal Article
• Language: Korean
• Published: 2019
• Subjects: Pathogens; Liver-expressed Antimicrobial Peptide 2 (LEAP-2); Duck; Disulfide Bond; Antimicrobial Peptides
• ISSN: 1011-2367; 1976-5517

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.