Cloning and secondary structure analysis of avian commercial broiler chicken interleukin-2 gene

Chicken interleukin 2(IL 2) was a kind of recently discovered cell factor. One specific pair of primers were designed according to IL 2 gene sequence published by Sundick et al. IL 2 cDNA gene was amplified by RT PCR method with the primers according to mRNA which was extracted from Avian commercial broiler chicken spleen cells stimulated by ConA. The gene was cloned into pGEM T Easy Vector and sequenced by the dideoxy mediated chain termination method. The results indicated that the full length chicken IL 2 cDNA was 734bp, encoding 143 amino acids. Compared with other 3 kinds of breed (Kestrel leghorn, Obese and SC ) chicken IL 2 from GenBank, the homology of nucleotide and dedued amino acid was 98.9%-100% and 97.2%-100% ,respectively . The predicted protein had a leader sequence composed of 22 amino acids, and four conserved cysteines allowing the formation of two intrachain disulfid bonds. Like mammalian IL 2, chicken IL 2 had four α helices. Phylogenetic tree analysis indicated that the Avian commercial broiler chicken IL 2 had closer relationship with SC chicken IL 2 than Turkey, Kestrel leghorn and Obese chicken IL 2.