Browsing by Author "Vigant, Frederic"
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- Broad-spectrum antivirals against viral fusionPublication . Vigant, Frederic; Santos, Nuno C.; Lee, BenhurEffective antivirals have been developed against specific viruses, such as HIV, Hepatitis C virus and influenza virus. This ‘one bug–one drug’ approach to antiviral drug development can be successful, but it may be inadequate for responding to an increasing diversity of viruses that cause significant diseases in humans. The majority of viral pathogens that cause emerging and re emerging infectious diseases are membrane-enveloped viruses, which require the fusion of viral and cell membranes for virus entry. Therefore, antivirals that target the membrane fusion process represent new paradigms for broad-spectrum antiviral discovery. In this Review, we discuss the mechanisms responsible for the fusion between virus and cell membranes and explore how broad-spectrum antivirals target this process to prevent virus entry
- A mechanistic paradigm for broad-spectrum antivirals that target virus-cell fusionPublication . Vigant, Frederic; Lee, Jihye; Hollmann, Axel; Tanner, Lukas B.; Ataman, Zeynep Akyol; Yun, Tatyana; Shui, Guanghou; Aguilar, Hector C.; Zhang, Dong; Meriwether, David; Roman-Sosa, Gleyder; Robinson, Lindsey R.; Juelich, Terry L.; Buczkowski, Hubert; Chou, Sunwen; Castanho, Miguel A. R. B.; Wolf, Mike C.; Smith, Jennifer K.; Banyard, Ashley; Kielian, Margaret; Reddy, Srinivasa; Wenk, Markus R.; Selke, Matthias; Santos, Nuno C.; Freiberg, Alexander N.; Jung, Michael E.; Lee, BenhurLJ001 is a lipophilic thiazolidine derivative that inhibits the entry of numerous enveloped viruses at non-cytotoxic concentrations (IC50≤0.5 mM), and was posited to exploit the physiological difference between static viral membranes and biogenic cellular membranes. We now report on the molecular mechanism that results in LJ001’s specific inhibition of viruscell fusion. The antiviral activity of LJ001 was light-dependent, required the presence of molecular oxygen, and was reversed by singlet oxygen (1O2) quenchers, qualifying LJ001 as a type II photosensitizer. Unsaturated phospholipids were the main target modified by LJ001-generated 1O2. Hydroxylated fatty acid species were detected in model and viral membranes treated with LJ001, but not its inactive molecular analog, LJ025. 1O2-mediated allylic hydroxylation of unsaturated phospholipids leads to a trans-isomerization of the double bond and concurrent formation of a hydroxyl group in the middle of the hydrophobic lipid bilayer. LJ001-induced 1O2-mediated lipid oxidation negatively impacts on the biophysical properties of viral membranes (membrane curvature and fluidity) critical for productive virus-cell membrane fusion. LJ001 did not mediate any apparent damage on biogenic cellular membranes, likely due to multiple endogenous cytoprotection mechanisms against phospholipid hydroperoxides. Based on our understanding of LJ001’s mechanism of action, we designed a new class of membrane-intercalating photosensitizers to overcome LJ001’s limitations for use as an in vivo antiviral agent. Structure activity relationship (SAR) studies led to a novel class of compounds (oxazolidine-2,4-dithiones) with (1) 100-fold improved in vitro potency (IC50<10 nM), (2) red-shifted absorption spectra (for better tissue penetration), (3) increased quantum yield (efficiency of 1O2 generation), and (4) 10–100-fold improved bioavailability. Candidate compounds in our new series moderately but significantly (p≤0.01) delayed the time to death in a murine lethal challenge model of Rift Valley Fever Virus (RVFV). The viral membrane may be a viable target for broad-spectrum antivirals that target virus-cell fusion.
- The rigid amphipathic fusion Inhibitor dUY11 acts through photosensitization of virusesPublication . Vigant, Frederic; Hollmann, Axel; Lee, Jihye; Santos, Nuno C.; Jung, Michael E.; Lee, BenhurRigid amphipathic fusion inhibitors (RAFIs) are lipophilic inverted-cone-shaped molecules thought to antagonize the membrane curvature transitions that occur during virus-cell fusion and are broad-spectrum antivirals against enveloped viruses (Broad-SAVE). Here, we show that RAFIs act like membrane-binding photosensitizers: their antiviral effect is dependent on light and the generation of singlet oxygen (1O2), similar to the mechanistic paradigm established for LJ001, a chemically unrelated class of Broad-SAVE. Photosensitization of viral membranes is a common mechanism that underlies these Broad-SAVE.