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 cod-ing for random 10- and 20-amino-acid peptide li-braries 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 syn-thesized, and further characterized. All of the pep-tides showed clear specific binding to the antibody. Two of them were further conjugated with Keyhole limpet hemocyanin (KLH) to immunize a rabbit. Af-ter 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 isola-tion of mimotopes for vaccines to substitute for ther-apeutic antibodies.