Isolation of mimotopes to the anti-human VEGF antibody Bevacizumab by mRNA display using random peptide libraries and the vaccination of a rabbit

An mRNA display system using synthetic DNA coding for random 10and 20-amino-acid peptide libraries was employed to isolate mimotopes that could substitute for the anti-human VEGF antibody Bevacizumab. After six rounds of affinity selection, three clones that bound to the antibody were isolated. Their random-peptide portions were chemically synthesized, and further characterized. All of the peptides showed clear specific binding to the antibody. Two of them were further conjugated with Keyhole limpet hemocyanin (KLH) to immunize a rabbit. After five immunizations biweekly, antibodies to the peptides were purified with a column conjugated with the peptides. The purified antibodies reacted specifically to the antibody’s original antigen, human VEGF. mRNA displays could be useful for the isolation of mimotopes for vaccines to substitute for therapeutic antibodies.