A functional IP10-scFv fusion protein retaining the antibody specificity for acidic isoferritin and chemokine function was produced at high level in Esherichia coli (E coli). IP10-scFv gene from the recombinant plasmid pc31P104c9 was subcloned into pET28a fused to N-terminal His-tag sequence in frame and overexpressed in E. coli BL21(DE3). With an on-column refolding procedure based on Ni-chelating chromatography, the active fusion protein was recovered efficiently from inclusion bodies with a refolding yield of approximate 45% confirmed by spectrophotometer. The activity of refolded IP10-scFv was determined through sodium dodecyl sulfate-polyacrylamide get electrophoresis, Western blotting and enzyme-linked immunosorbent assay. The results showed the fusion protein retains the specific binding activity to At F with an affinity constant of 4.48 x 10(-8) M as well as the chemokine function of IP-10. The overall yield of IP10-scFv with bioactivity in E. coli flask culture was more than 40 mg/L. (C) 2005 Elsevier Inc. All rights reserved.