Discovery of Anas platyrhynchos avian beta-defensin 2 (Apl_AvBD2) with antibacterial and chemotactic functions

作者：Soman Soja Saghar; Arathy D S; Sreekumar E^*

来源：Molecular Immunology, 2009, 46(10): 2029-2038.

DOI：10.1016/j.molimm.2009.03.003

• Antimicrobial peptides
• Avian
• Bacterial expression
• cDNA library
• Subtraction

The cationic, cysteine-rich peptides called beta-defensins play a major role in the innate immune response. Here, we describe the identification and characterization of the duck beta-defensin-2 homologue, Anas platyrhynchos avian beta-defensin 2 (Apl_AvBD2). The 195 base pair open reading frame (ORF) of Apl_AvBD2 has 83% identity with Gga_AvBD2 (chicken) and 85% identity with Mga_AvBD2 (turkey) at nucleotide level. The gene corresponding to the coding region is comprised of three exons and two introns in both Apl_AvBD2 and Gga_AvBD2. The predicted secondary structure of Apl_AvBD2 has the classical "beta-defensin core motif' formed by the P-sheet rich structure. Apart from mild expression in tissues like kidney, lung, brain, bursa of Fabricious and ovary, Apl_AvBD2 mRNA show a very high level constitutive expression in bone marrow and spleen, indicating that it is a myeloid defensin. Purified recombinant Apl_AvBD2 demonstrated in vitro antibacterial activity against both Gram-positive and Gram-negative bacteria, with a minimum bactericidal concentration (MBC) of 3.7 mu M against Micrococcus luteus NCIM 2871 and Escherichia coli NCIM 2685, and of 2.2 mu M against Reimerella anatipestifer. The immunomodulatory potential of Apl_AvBD2 was shown by chemotaxis of DT-40 chicken B-lymphocytes. The widespread tissue distribution and the potent bactericidal and chemotactic activity make Apl_AvBD2 an important molecule in the innate immune response in ducks. It may play a vital role in the immune response of these birds against bacterial and viral pathogens.

• 出版日期2009-6