Discovery of Anas platyrhynchos avian beta-defensin 2 (Apl_AvBD2) with antibacterial and chemotactic functions.
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 beta-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 microM against Micrococcus luteus NCIM 2871 and Escherichia coli NCIM 2685, and of 2.2 microM 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.
Molecular Immunology & Virology Laboratory, Department of Molecular Microbiology, Rajiv Gandhi Centre for Biotechnology (RGCB), Thycaud PO, Trivandrum 695014, Kerala, India.
Soja Saghar
SS
Soman
D S
DS
Arathy
E
E
Sreekumar
D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects; D002460:Cell Line; D002633:Chemotaxis / Q000187:drug effects*; D002645:Chickens; D055808:Drug Discovery; D004372:Ducks / Q000378:metabolism*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D016678:Genome / Q000235:genetics; D006801:Humans; D008826:Microbial Sensitivity Tests; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000494:pharmacology; D017422:Sequence Analysis, DNA; D023083:beta-Defensins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D012333:RNA, Messenger; D011994:Recombinant Proteins; D023083:beta-Defensins