Gene cloning and mature protein expression of chicken interleukin-18 in Escherichia coli

Chicken interleukin-18(ChIL-18) gene was amplified from total RNA extracted directionally from Luoman chicken splenocytes by reverse transcription-polymerase chain reaction(RT-PCR).PCR product was cloned into pGEM-T Easy vector and sequenced.The result showed that the nucleotide sequence of chicken IL-18 gene was 597 bp,including the stop coden and the same as the published chicken IL-18 cDNA sequence by Schneider K.A prokaryotic expression plasmid of chicken IL-18 gene,pGEX-ChIL-18,was obtained by subcloning the encoding region of chicken IL-18 mature peptide gene into pGEX-4T-1.The recombinant chicken IL-18 was expressed efficiently in pGEX-ChIL-18-transformed BL21(DE3) LysS induced by IPTG,the yield accounted for 18.6%of the total bacterial protein.The results showed that fusion protein GST-ChIL-18 was about 46 kDa and could react with monoclonal antibody for chicken IL-18.After purified by Glutathione Sepharose-4B affinity column,chicken IL-18 protein induced obvious proliferation of chicken splenocytes in vitro.