Screening and Functional Profiling of Small-Molecule HIV-1 Entry and Fusion Inhibitors.
HIV-1 entry and fusion with target cells is an important target for antiviral therapy. However, a few currently approved treatments are not effective as monotherapy due to the emergence of drug resistance. This consideration has fueled efforts to develop new bioavailable inhibitors targeting different steps of the HIV-1 entry process. Here, a high-throughput screen was performed of a large library of 100,000 small molecules for HIV-1 entry/fusion inhibitors, using a direct virus-cell fusion assay in a 384 half-well format. Positive hits were validated using a panel of functional assays, including HIV-1 specificity, cytotoxicity, and single-cycle infectivity assays. One compound-4-(2,5-dimethyl-pyrrol-1-yl)-2-hydroxy-benzoic acid (DPHB)-that selectively inhibited HIV-1 fusion was further characterized. Functional experiments revealed that DPHB caused irreversible inactivation of HIV-1 Env on cell-free virions and that this effect was related to binding to the third variable loop (V3) of the gp120 subunit of HIV-1 Env. Moreover, DPHB selectively inhibited HIV-1 strains that use CXCR4 or both CXCR4 and CCR5 co-receptors for entry, but not strains exclusively using CCR5. This selectivity was mapped to the gp120 V3 loop using chimeric Env glycoproteins. However, it was found that pure DPHB was not active against HIV-1 and that its degradation products (most likely polyanions) were responsible for inhibition of viral fusion. These findings highlight the importance of post-screening validation of positive hits and are in line with previous reports of the broad antiviral activity of polyanions.
1 Department of Pediatrics Infectious Diseases, Emory University School of Medicine , Atlanta, Georgia .
Charline
C
Giroud
2 Department of Pharmacology, Emory University School of Medicine , Atlanta, Georgia .|3 Emory Chemical Biology Discovery Center, Emory University School of Medicine , Atlanta, Georgia .
Yuhong
Y
Du
1 Department of Pediatrics Infectious Diseases, Emory University School of Medicine , Atlanta, Georgia .
Mariana
M
Marin
2 Department of Pharmacology, Emory University School of Medicine , Atlanta, Georgia .|3 Emory Chemical Biology Discovery Center, Emory University School of Medicine , Atlanta, Georgia .
Qui
Q
Min
4 Department of Chemistry, Emory University , Atlanta, Georgia .
Nathan T
NT
Jui
2 Department of Pharmacology, Emory University School of Medicine , Atlanta, Georgia .|3 Emory Chemical Biology Discovery Center, Emory University School of Medicine , Atlanta, Georgia .|5 Department of Hematology and Medical Oncology, Winship Cancer Institute , Atlanta, Georgia .
Haian
H
Fu
1 Department of Pediatrics Infectious Diseases, Emory University School of Medicine , Atlanta, Georgia .|6 Children's Healthcare of Atlanta , Atlanta, Georgia .
Gregory B
GB
Melikyan
D055808:Drug Discovery; D004353:Drug Evaluation, Preclinical / Q000379:methods*; D023581:HIV Fusion Inhibitors / Q000008:administration & dosage*; D015497:HIV-1 / Q000187:drug effects*; D025941:Protein Interaction Mapping / Q000379:methods*; D014760:Viral Fusion Proteins / Q000037:antagonists & inhibitors*; D053586:Virus Internalization / Q000187:drug effects*
D023581:HIV Fusion Inhibitors; D014760:Viral Fusion Proteins
HIV envelope glycoprotein; V3 loop; fusion inhibitor; fusion intermediates; virus inactivation