Immunodetection of recombinant scFv-intimin. E. coli BL21(DE3)pLysS extracts were submitted to 12% SDS/PAGE, transferred to nitrocellulose membrane and detected by immunoblotting with mouse anti-His antibody. Lane 1. Total extract as control of pre-induction. Lane 2. Total extract of bacterial cells after induction. Lane 3. Soluble fraction of bacterial extract. Lane 4. Insoluble fraction of bacterial extract (inclusion bodies) treated with 8 M urea. Recombinant protein containing 6-histidine residues detected by anti-His antibody is indicated by the arrow.