Fluoxazolevir inhibits hepatitis C virus infection in humanized chimeric mice by blocking viral membrane fusion

Abstract

Fluoxazolevir is an aryloxazole-based entry inhibitor of hepatitis C virus (HCV). We show that fluoxazolevir inhibits fusion of HCV with hepatic cells by binding HCV envelope protein 1 (E1) to prevent fusion. 9 of 10 fluoxazolevir-resistance-associated substitutions are in the E1 protein and 4 are in a putative fusion peptide. Pharmacokinetic studies in mice, rats and dogs revealed that fluoxazolevir localizes to the liver. A four-week intraperitoneal regimen of fluoxazolevir in humanized chimeric mice infected with HCV genotype 1b, 2a or 3 resulted in a 2-log reduction in viremia, without evidence of drug resistance. In comparison, daclatasvir, an approved HCV drug, suppressed more than 3-log of viremia but is associated with emergence of resistance-associated substitutions in mice. Combination therapy using fluoxazolevir and daclatasvir cleared HCV genotypes 1b and 3 in mice. Fluoxazolevir combined with glecaprevir and pibrentasvir was also effective in clearing multidrug-resistant HCV replication in mice. Fluoxazolevir may be promising as the next generation of combination drug cocktails for HCV treatment.

RETRACTED ARTICLE: Thiophen urea derivatives as a new class of hepatitis C virus entry inhibitors

“…The essential players in HCV virus entry are HCV glycoproteins E1 and E2, which form a heterodimer and constitute viral envelope proteins [18][19][20] . HCV E1 does not directly interact with host receptors, whereas E2 directly binds with host receptors, such as the CD81 receptor 21 .…”

Inhibition of SARS-CoV-2 pseudovirus invasion by ACE2 protecting and Spike neutralizing peptides: An alternative approach to COVID19 prevention and therapy

“…Molecular Docking. Molecular docking for peptide-protein interactions was computationally simulated by XtalPi AI Research Center (XARC, Beijing, China) using Rosetta FlexPepDock 40 . The SARS-CoV-2 S-protein structure (PDBID: 6LZG) and human ACE2 structure (PDBID: 6LZG) were used as initial models for computational simulations.…”

Small-Molecule Inhibition of Viral Fusion Glycoproteins

“…While the location of 18a's cross-links to E1 were not mapped, a diazirineconjugated CCZ analog was shown to covalently modify E1 residues 214, 215, and 221 (162). Mutations that confer resistance without loss of viral fitness map to the predicted fusion loop for both 18a (Ala274Ser, Ile374Thr, Asp382Glu, and Val414Ala) (161) and CCZ (Met267Val, Ala274Thr, Leu286Ile, Gln289His, Phe291Leu, Met267Val/Phe291Leu, and Leu286Ile/Phe291Leu) (162). The location of these mutations suggests that 18a and CCZ may directly hinder function of the predicted fusion loop; however, the possibility that these mutations act by a more general mechanism (e.g., by destabilizing a prefusion conformation, analogously to the mutations conferring TBHQ-resistance to influenza virus and F inhibitor-resistance to RSV) cannot currently be excluded.…”

“…Multiple compounds affecting an early step in the replication cycle were identified from an ∼350,000member library (159). A subsequent medicinal chemistry effort to optimize the antiviral activity and biopharmaceutical and pharmacokinetic properties of a set of related aryloxazoles led to the development of compound 18a (fluoxazolevir), which inhibits multiple HCV genotypes in cell culture (EC 50 values 0.008-2.007 μM) (160,161). Most impressively, tests of 18a against HCV genotypes 1b, 2a, and 3 in the humanized chimeric mouse model of infection demonstrated 1-2log decreases in viral titer as well as activity against multidrug-resistant HCV mutants.…”

“…Although inhibition of E1/E2-mediated membrane fusion could not be assayed directly for 18a or CCZ, time-ofaddition experiments and experiments in which viral attachment, internalization, and fusion were synchronized through control of temperature and endosomal pH are consistent with effects on fusion. In photo-cross-linking experiments, derivatives of 18a and CCZ were shown to crosslink to E1 when incubated with an E1/E2 protein (residues 192-746) expressed recombinantly in a lentivirus expression system (161) or when added directly to HCV-infected cells in culture (162), respectively. While the location of 18a's cross-links to E1 were not mapped, a diazirineconjugated CCZ analog was shown to covalently modify E1 residues 214, 215, and 221 (162).…”