Bioinformatic discovery and initial characterisation of nine novel antimicrobial peptide genes in the chicken

Abstract

Antimicrobial peptides (AMPs) are essential components of innate immunity in a range of species fromDrosophila 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 proteinspredicted 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.

Chicken cathelicidin-B1, an antimicrobial guardian at the mucosal M cell gateway

“…All of these cathelicidin genes have four exons, except for chCATH-2, which has an additional exon, Ib, that is predicted to be incapable of encoding functional protein products (data not shown). The three chicken cathelicidin relatives of mammalian cathelicidins have been identified recently by other investigators on the basis of sequence similarity and antimicrobial activity (24)(25)(26) and have been given the names fowlicidin 1, 2, and 3 (26).…”

Different effect of doxycycline and enrofloxacin on cathelicidin-3 mRNA expression in chickens with or without probiotics supplementation

“…High to medium levels of expression of the cathelicidin-1 were described from the crop to the small and large intestines of chickens. The liver levels of cathelicidin-1 were low and those of the cathelicidin-2 were higher (Lynn et al, 2004;van Dijk et al, 2005). Their activity against Gram-positive and Gramnegative microorganisms and also against pathogenic fungi and nematodes has been demonstrated (Scocchi et al, 2005).…”

“…Cathelicidins are antimicrobial peptides and expression of four cathelicidins was described in poultry so far (Lynn et al, 2004;van Dijk et al, 2005;. These are the cathelicidin-1 or fowlicidin-1 (Lynn et al, 2004), chicken myeloid antimicrobial peptide 27 (CMAP27) or fowlicidin-2 (van Dijk et al, 2005), third chicken cathelicidin fowlicidin-3 (Xiao et al, 2006) and cathelicidin-B1 (Goitsuka et al, 2007). Cathelicidins were found predominantly in epithelial cells in the gastrointestinal tract and kidney, and in myeloid tissue (Sang & Blecha, 2009).…”

“…Antimicrobial peptides are considered key factors in innate immunity by providing a first line of defense of the body against potential pathogens in mammals and birds (Michailidis, 2010). Cathelicidins are antimicrobial peptides and expression of four cathelicidins was described in poultry so far (Lynn et al, 2004;van Dijk et al, 2005;. These are the cathelicidin-1 or fowlicidin-1 (Lynn et al, 2004), chicken myeloid antimicrobial peptide 27 (CMAP27) or fowlicidin-2 (van Dijk et al, 2005), third chicken cathelicidin fowlicidin-3 (Xiao et al, 2006) and cathelicidin-B1 (Goitsuka et al, 2007).…”

Adaptive response of Pinus monticola driven by positive selection upon resistance gene analogs (RGAs) of the TIR-NBS-LRR subfamily

“…An NJ tree at amino acid level and the respective nucleotide alignment were both used in the CODEML and CODEMLSITES analyses according to Lynn et al (2004aLynn et al ( , 2004b; details of the exact methods for these analyses are found in Zambounis et al (2012). Briefly, the amino acid sequence alignment was conducted by employing the MUSCLE software (Edgar 2004), whilst the construction of the respective phylogenetic tree was performed using the MEGA 5 software (Tamura et al 2011).…”