Antimicrobialpeptides are crucial elements of the host non-specific innate immune systemwhich play a major role as natural antibiotics by providing first line defenseagainst microbial incursion. (Hancock etal., 2006, Zasloff.,2002). AMPs aregenerally short, cationic, amphipathic and structurally diverse molecules thatare widely present in nearly all life form 1. These molecules displayextensive and strong antimicrobial activity against microbial assault primarilyby destroying membrane integrity of the invading pathogens.
Apart from being antimicrobial, AMPs performimmunomodulatory roles also by recruiting and activating innate and adaptiveimmune cells; hence they were named as host defense peptides. Majorityof the AMPs are encoded by distinct genes, and a large number of structurallydifferent HDPs normally exist in a single species. Different groups of AMPsreported in birds include NK-lysin (Cuperus et al. 2013; Ishige et al. 2014),cathelicidin (Cuperus et al. 2013), liver-expressed antimicrobial peptide 2(Cuperus et al.
2013) and avian ?-defensin (Cuperus et al. 2013; Ishige et al.2015a) which endow them with tremendous innate immunity.Liver-expressedantimicrobial peptide 2 (LEAP-2) is the second blood-derived peptide isolatedfirstly from human blood and displays antimicrobial activity and predominantexpression in the liver.
(Krause et al., 2003). This peptidebelongs to cystein rich family of AMPs characterized by the presence of a fourcystein conserved motif and two intracellular disulphide bridges.
LEAP2 hasbeen characterized from few organisms like human, monkey, pig, mouse, cow, andchicken 8-12. In chicken, Cleap2 gene consists of three exonsand two introns, has been reported to be localized in chromosome 13 ofchicken genome. Like other cationic HDP, LEAP2 also possess a signalpeptide, a prepropeptide and an active mature peptide. Cleap2 gene encodes a 76 amino acid prepropeptide which is enzymatically processedby furin family of propeptide convertase to release mature peptide of 40 aminoacid. The RXXR motif at cleavage site between prodomain and mature region ofLEAP2 is conserved throughout vertebrates. Studies suggest that Human andchannel catfish LEAP2 gene express several splicing variants as a result ofalternative splicing. It is possible that LEAP2 gene employ splicing as a majormechanism of its regulation.In the present study, we compared the nucleotide and proteinsequences of avian LEAP2