Cloning and prokaryotic expression of chicken interleukin-5 gene.

According to a forecast sequence of chicken interleukin-5(ChIL-5) gene published in GenBank,a pair of primers was designed and used for cloning ChIL-5 gene by RT-PCR from chicken spleen lymphocytes stimulated by ConA for the first time.The complete nucleotide sequence of the cloned gene contained a 381bp open reading frame encoding 126 amino acids,including the sequence encoding 22-amino-acid signal peptide.The protein encoded by the gene was about 14.63ku in molecular weight.The amino acid sequence deduced from the gene had less than 25% similarity to that of other mammals.However,the predicted tertiary structure of ChIL-5 protein was similar to that of the human,and the structure of the protein mainly consisted of four α-helix.This gene was cloned into pET-28a(+) vector to construct recombinant expression plasmid pET-28a-IL-5,then the recombinant plasmid was transformed into Escherichia coli Rosetta(DE3) and expressed under induction of IPTG.The prokaryotic expression of ChIL-5 gene provided foundation for further studies of the structure and biological function of avian IL-5.