Bioinformatic discovery and initial characterisation of nine novel antimicrobial peptide genes in the chicken
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Antimicrobial peptides (AMPs) are essential components of innate immunity in a range of species from Drosophila to humans and are generally thought to act by disrupting the membrane integrity of microbes. In order to discover novel AMPs in the chicken, we have implemented a bioinformatic approach that involves the clustering of more than 420,000 chicken expressed sequence tags (ESTs). Similarity searching of proteins—predicted to be encoded by these EST clusters—for homology to known AMPs has resulted in the in silico identification of full-length sequences for seven novel gallinacins (Gal-4 to Gal-10), a novel cathelicidin and a novel liver-expressed antimicrobial peptide 2 (LEAP-2) in the chicken. Differential gene expression of these novel genes has been demonstrated across a panel of chicken tissues. An evolutionary analysis of the gallinacin family has detected sites—primarily in the mature AMP—that are under positive selection in these molecules. The functional implications of these results are discussed.
KeywordsChicken Defensins Antimicrobial peptide Innate immune system
This research was supported by the Food Institutional Research Measure grant no. 01/R&D/D/135 from the Irish Department of Agriculture, Food and Rural Development. All experiments described in this manuscript comply with the current laws of the Republic of Ireland. Authors David Lynn and Rowan Higgs contributed equally to this work.
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