The aim of this project is the synthesis of bispecific antibody paratope mimicking peptides with high target binding affinity and HIV-1 neutralization strength. In comparison to the original broadly neutralizing HIV-1 antibodies (bnAbs) from which these peptides are derived, bispecific paratope mimics are designed to bind two epitopes on the HIV-1 envelope glycoprotein complex (Env) at once. This concept complies with recent studies pointing out therapeutical benefits of combinations of bnAbs over bnAb monotherapy in HIV-1 infected patients, as well as the development of bispecific antibodies (bsAbs) that are already used in cancer therapy. Using bispecific antibody paratope mimics as a replacement for bsAbs or a combination of bnAbs might have further advantages, since it is assumed that such peptides provide e.g. better tissue penetration, access to sterically shielded epitopes, lower immunogenicity and the possibility to improve binding affinity or bioavailability by chemical insertion of non-proteinogenic amino acids or cyclization. Corresponding research has been done on a number of single human antibodies, including HIV-1 antibodies.
This project will apply the principle of bispecific antibody paratope mimics on a number of bnAbs, including PGT121, PG16 and 10E8. The peptide mimics will be rationally designed, synthesized using solid-phase peptide synthesis (SPPS), purified by preparative HPLC and tested for binding in various ELISA, SPR and Fluorescence Polarization setups.