Objective: Objective To study high-level expression and purification of recombinant mature human IL-18(mhIL-18)in E.coli with soluble form.Methods: The gene of mhIL-18 was amplified with PCR.Then

the recombinant expression plasmid pTYB1IL-18 was constructed by cloning mhIL-18 into pTYB1 vector and transformed to E.coli ER2566.IPTG was added into the E.coli ER2566 culture to express recombinant fusion protein.After the harvested bacteria dispersed with ultrasound

SDS-PAGE and Western blot were used to analyze the expression of recombinant fusion protein.The activity of mhIL-18 which had been purified by affinity chromatography was tested by MTT.Results:The cloned sequence of mhIL-18 was identical with the sequence in GenBank.After the induction by IPTG inducing

the fusion protein of mhIL-18 covered over 26% total bacterial proteins

which included 80% active fusion protein.Purification of recombinant expressed mhIL-18 purity was 95%

which had the activity of the mhIL-18.Conclusion: High level expression and purification of recombinant human IL-18 is succeeded which has the activity.