Fig. 3

Specific peptide epitopes against XC24 antibody screened from phage display random cyclic hepta-peptide library. a Biopanning with XC24 autoantibody against M13 phage display random cyclic hepta-peptide library to screen mimotopes specific to XC24 autoantibody; b Phage ELISA of selected epitopes against XC24 autoantibody. XC20, another HBx-Tg mouse-derived autoantibody, was used as a control antibody; c Effect of reducing disulfide bonds on the reactivity of cyclic peptide mimotopes against XC24 autoantibody. The cyclic mimotope display phages, either untreated (Cyclic) or treated with dithiothreitol and iodoacetamide (Reduced), were tested for their responses to XC24 autoantibody; d Competitive inhibition of XC24 autoantibody binding to HepG2 cells by XC24 mimotopes (XC24p1, XC24p8 and XC24p11). Fixed and permeabilized HepG2 cells were treated with XC24 autoantibody, which was pre-adsorbed with the indicated phages (10¹¹ or 10¹² pfu). The reactivity of the phage-added reaction was compared to that of phage-free reaction; e Western blot analysis of competitive inhibition of XC24 autoantibody binding to tumor cells by XC24 mimotopes (XC24p1, XC24p8, and XC24p11). Cell lysates were blotted and treated with XC24 autoantibody, which was pre-adsorbed with XC24 mimotope display M13 phages (10¹¹ pfu) or with control M13 phage (Eph)