Abstract：The hIFN-V/TNF-Ufusion protein(hVTNF-U ) recombinant gene was cloned to the expression vector pET28, and a T7lac promoter-based fusion expression plasmid w as constructed that directed the synthesis of hVTN F-Uin E. coli as fusion with a stretch of six consecutive histidine residues( H is6-tag) at N terminus. SDS-PAGE analysis revealed that with IPT G(1m M) induction the strain bearing the plasmid highly expresses the target protein ( 32kD) which molecular w eight is same as the theory molecular w eight of His6-VTNF-U , and expression level of the product( as insoluble inclusion bodies, IBs) is above 45% of the total bacterial proteins. After cell lysis, the IBs is pelleted by centrifugation, dissolves in 7M urea, then purifies in one step by Ni column( Ni2 + -sepharose 6B). And the purity of
more than 96% and the recovery of 91% w ere obtained. The purified product was refolded under low temperature( < 10℃ ). The specific cytotoxic activity and the specific antiviral activity of the renaturation product are 1. 2× 10 7 ～ 2. 0× 107 u/mgp and 6. 6× 105～ 7 . 2× 105 u/mgp respectively
