A novel HIV-1 inhibitor that blocks viral replication and rescues APOBEC3s by interrupting vif/CBFb interaction

Abstract

HIV remains a health challenge worldwide, partly because of the continued development of resistance to drugs. Therefore, it is urgent to find new HIV inhibitors and targets. Apolipoprotein B mRNA-editing catalytic polypeptide-like 3 family members (APOBEC3) are important host restriction factors that inhibit HIV-1 replication by their cytidine deaminase activity. HIV-1 viral infectivity factor (Vif) promotes proteasomal degradation of APOBEC3 proteins by recruiting the E3 ubiquitin ligase complex, in which core-binding factor b (CBFb) is a necessary molecular chaperone. Interrupting the interaction between Vif and CBFb can release APOBEC3 proteins to inhibit HIV-1 replication and may be useful for developing new drug targets for HIV-1. In this study, we identified a potent small molecule inhibitor CBFb/Vif-3 (CV-3) of HIV-1 replication by employing structure-based virtual screening using the crystal structure of Vif and CBFb (PDB: 4N9F) and validated CV-3's antiviral activity. We found that CV-3 specifically inhibited HIV-1 replication (IC50 = 8.16 mM; 50% cytotoxic concentration >100 mM) in nonpermissive lymphocytes. Furthermore, CV-3 treatment rescued APOBEC3 family members (human APOBEC3G (hA3G), hA3C, and hA3F) in the presence of Vif and enabled hA3G packaging into HIV-1 virions, which resulted in Gly-to-Ala hypermutations in viral genomes. Finally, we used FRET to demonstrate that CV-3 inhibited the interaction between Vif and CBFb by simultaneously forming hydrogen bonds with residues Gln-67, Ile-102, and Arg-131 of CBFb. These findings demonstrate that CV-3 can effectively inhibit HIV-1 by blocking the interaction between Vif and CBFb and that this interaction can serve as a new target for developing HIV-1 inhibitors.