A stable hepatitis D virus-producing cell line for host target and drug discovery.

Chronic hepatitis D is the most aggressive form of chronic viral hepatitis. It is caused by super-infection of hepatitis B virus (HBV)-infected hepatocytes with hepatitis D virus (HDV). While the recent conditional approval of bulevirtide for HDV treatment offers a new therapeutic modality in Europe, there is an unmet medical need to further improve therapy. A more detailed characterization of virus-host interactions is needed for the identification of novel therapeutic targets. Addressing this need, we engineered a new stably-transformed cell line, named HuH7-2C8D, producing high titer recombinant HDV and allowing the study of viral particles morphogenesis and infectivity. Using this culture system, where viral propagation by re-infection is limited, we observed an increased accumulation of edited version of the viral genomes within secreted HDV viral particles over time that is accompanied with a decrease in viral particle infectivity. We confirmed the interaction of HDV proteins with a previously described host factor in HuH7-2C8D cells and additionally showed that these cells are suitable for co-culture assays with other cell types such as macrophages. Finally, the use of HuH7-2C8D cells allowed to confirm the dual antiviral activity of farnesyl transferase inhibitors, including the clinical candidate lonafarnib, against HDV. In conclusion, we have established an easy-to-handle cell culture model to investigate HDV replication, morphogenesis, and host interactions. HuH7-2C8D cells are also suitable for high-throughput antiviral screening assays for the development of new therapeutic strategies.

Structure-Based Drug Design of Potent Pyrazole Derivatives against Rhinovirus Replication.

Rhinoviruses (RVs) have been linked to exacerbations of many pulmonary diseases, thus increasing morbidity and/or mortality in subjects at risk. Unfortunately, the wide variety of RV genotypes constitutes a major hindrance for the development of Rhinovirus replication inhibitors. In the current investigation, we have developed a novel series of pyrazole derivatives that potently inhibit the Rhinovirus replication. Compounds 10e and 10h behave as early stage inhibitors of Rhinovirus infection with a broad-spectrum activity against RV-A and RV-B species (EC50 < 0.1 µM). We also evaluate the dynamics of the emerging resistance of these promising compounds and their in vitro genotoxicity. Molecular docking experiments shed light on the pharmacophoric elements interacting with residues of the drug-binding pocket.

Novel therapeutic approaches to simultaneously target rhinovirus infection and asthma/COPD pathogenesis.

Rhinoviruses are exclusive respiratory pathogens and the etiological agents of the common cold. These viruses are increasingly reported to cause exacerbations of asthma and chronic obstructive pulmonary disease (COPD). Here, we review the role of rhinovirus infections in the pathogenesis of asthma and COPD and we discuss the current and potential future treatments. We propose that, in order to prevent exacerbations, the design of novel therapeutics should focus on directly acting antivirals but also include the design of drugs that simultaneously inhibit viral replication and alleviate symptoms of asthma and COPD.

Heterocyclic pharmacochemistry of new rhinovirus antiviral agents: A combined computational and experimental study.

Rhinovirus (RV), member of the Enterovirus genus, is known to be involved in more than half of the common colds. Through advances in molecular biology, rhinoviruses have also been associated with exacerbations of chronic pulmonary diseases (e.g. asthma, chronic obstructive pulmonary disease (COPD) and cystic fibrosis). In the current investigation, we develop a novel series of 4,5-dimethoxybenzyl derivatives that potently inhibits rhinovirus replication. Compound (S)-7f blocks RV-B14 replication with an EC50 value of 0.25 µM and shows a low toxicity in HeLa cells (CC50 > 271 µM). Enantioseparation followed by an absolute configuration determination by a Mosher's method revealed the interest of enantiopure compounds. Molecular docking studies permitted the identification of key biological interactions within the drug-binding pocket and an in silico drug-like study revealed a good potential for the development of these derivatives.

A Novel Series of Highly Potent Small Molecule Inhibitors of Rhinovirus Replication.

Human rhinoviruses (hRVs) are the main causative pathogen for common colds and are associated with the exacerbation of asthma. The wide variety in hRV serotypes has complicated the development of rhinovirus replication inhibitors. In the current investigation, we developed a novel series of benzothiophene derivatives and their analogues (6-8) that potently inhibit the replication of both hRV-A and hRV-B strains. Compound 6g inhibited the replication of hRV-B14, A21, and A71, with respective EC50 values of 0.083, 0.078, and 0.015 µM. The results of a time-of-addition study against hRV-B14 and hRV-A16 and resistant mutation analysis on hRV-B14 implied that 6g acts at the early stage of the viral replication process, interacting with viral capsid protein. A molecular docking study suggested that 6g has a capsid-binding mode similar to that of pleconaril. Finally, derivatives of 6 also displayed significant inhibition against poliovirus 3 (PV3) replication, implying their potential inhibitory activities against other enterovirus species.

VP1 crystal structure-guided exploration and optimization of 4,5-dimethoxybenzene-based inhibitors of rhinovirus 14 infection.

Human rhinoviruses (HRV) are the predominant cause of common colds and flu-like illnesses, but are also responsible for virus-induced exacerbations of asthma and chronic obstructive pulmonary disease. However, to date, no drug has been approved yet for clinical use. In this study, we present the results of the structure-based lead optimization of a class of new small-molecule inhibitors that we previously reported to bind into the pocket beneath the canyon of the VP1 protein. A small series of analogues that we designed based on the available structure and interaction data were synthesized and evaluated for their potency to inhibit the replication of HRV serotype 14. 2-(4,5-Dimethoxy-2-nitrophenyl)-1-(4-(pyridin-4-yl)phenyl)ethanol (3v) was found to be a potent inhibitor exhibiting micromolar activity (EC50 = 3.4 ± 1.0 µM) with a toxicity for HeLa cells that was significantly lower than that of our previous hit (LPCRW_0005, CC50 = 104.0 ± 22.2 µM; 3v, CC50 > 263 µM).

Understanding the molecular mechanism of host-based statin resistance in hepatitis C virus replicon containing cells.

A number of statins, the cholesterol-lowering drugs, inhibit the in vitro replication of hepatitis C virus (HCV). In HCV-infected patients, addition of statins to the earlier standard of care therapy (pegIFN-α and ribavirin) resulted in increased sustained virological response rates. The mechanism by which statins inhibit HCV replication has not yet been elucidated. In an attempt to gain insight in the underlying mechanism, hepatoma cells carrying an HCV replicon were passaged in the presence of increasing concentrations of fluvastatin. Fluvastatin-resistant replicon containing cells could be generated and proved ∼8-fold less susceptible to fluvastatin than wild-type cultures. The growth efficiency of the resistant replicon containing cells was comparable to that of wild-type replicon cells. The fluvastatin-resistant phenotype was not conferred by mutations in the viral genome but is caused by cellular changes. The resistant cell line had a markedly increased HMG-CoA reductase expression upon statin treatment. Furthermore, the expression of the efflux transporter P-gp was increased in fluvastatin-resistant replicon cells (determined by qRT-PCR and flow cytometry). This increased expression resulted also in an increased functional transport activity as measured by the P-gp mediated efflux of calcein AM. In conclusion, we demonstrate that statin resistance in HCV replicon containing hepatoma cells is conferred by changes in the cellular environment.