Optimization of a Piperidine CD4-Mimetic Scaffold Sensitizing HIV-1 Infected Cells to Antibody-Dependent Cellular Cytotoxicity

The ability of the HIV-1 accessory proteins Nef and Vpu to decrease CD4 protects infected cells from antibody-dependent cellular cytotoxicity (ADCC) by limiting the exposure of vulnerable epitopes to envelope glycoprotein (Env). Small-molecule CD4 mimetics (CD4mcs) based on piperidine scaffolds represent a new family of agents capable of sensitizing HIV-1-infected cells to ADCC by exposing CD4-induced (CD4i) epitopes on Env that are recognized by non-neutralizing antibodies which are abundant in plasma of people living with HIV. Here, we employed the combined methods of parallel synthesis, structure-based design, and optimization to generate a new line of piperidine-based CD4mcs, which sensitize HIV-1 infected cells to ADCC activity. The X-ray crystallographic study of the CD4mcs within the gp120 residues suggests that the positioning of the CD4mc inside the Phe43 cavity and synergistic contact of the CD4mc with the β20–21 loop and the α1-helix lead to improved antiviral activity.