The Bioactive Lipid 4-Hydroxyphenyl Retinamide Inhibits Flavivirus Replication

Abstract

Dengue virus (DENV) is a mosquito-borne pathogen that is the causative agent of dengue fever. Severe dengue virus infection is potentially fatal due to hemorrhaging, plasma leakage, and pulmonary shock. The four serotypes of DENV (DENV-1 to DENV-4) are defined by antigenic differences on the viral envelope protein, E, and together, they comprise a species within the Flavivirus genus of the Flaviviridae family. This family of small enveloped viruses with positive-sense RNA genomes encompasses other human pathogens, including West Nile virus (WNV), Japanese encephalitis virus (JEV), yellow fever virus (YFV), and hepatitis C virus (HCV). A recent evidence-based study suggests that approximately 300 million DENV infections occur annually (1), and no vaccine or specific antiviral drug is currently available to treat it. DENV vaccine development is a major challenge due to the antibody-dependent enhancement of infection, a phenomenon in which neutralizing antibodies against one DENV serotype can exacerbate disease upon subsequent infection with another serotype (2, 3). A parallel exploration of antiviral strategies to combat DENV infection is therefore crucial.Resistance to antiviral drugs that act against viral targets occurs rapidly due to the intrinsically high mutation rate of RNA virus polymerases. Host-targeted antivirals that can complement these more traditional antivirals may make the acquisition of resistance to antiviral drugs much less likely and may also offer broad-spectrum activity against phylogenetically related viruses. The interactions between DENV and host lipid biosynthetic, metabolic, trafficking, and signal transducing pathways represent a rich and largely unexplored class of targets for host-targeted antiviral strategies. DENV and other RNA viruses rely entirely on host lipids to supply the membranes essential for the viral replication cycle, and the interaction of viruses with lipid-related processes in the host cell is highlighted by recent studies documenting specific perturbations of these pathways by viruses (4). In addition, so-called bioactive lipids can regulate cellular processes by modulating signal transduction cascades that may impinge on viral infection. Thus, small molecules that act on host-cell lipid signaling and metabolism are attractive as potential anti-DENV compounds.To pursue the strategy of targeting host lipid metabolic and signaling pathways important for DENV infection, we screened a panel of bioactive lipids and small-molecule inhibitors of lipid metabolism for activity against DENV. We chose a library enriched for compounds with known safety and bioavailability profiles to increase our likelihood of identifying clinically useful anti-DENV compounds. We present here the identification of the bioactive lipid 4-hydroxyphenyl retinamide (4-HPR) as an inhib-

Differential utilisation of ceramide during replication of the flaviviruses West Nile and dengue virus

“…Although ceramide is redistributed to the sites of WNV KUN replication, acute chemical inhibition of SPT, a central enzyme in the ceramide de novo synthesis pathway, by myriocin did not affect WNV KUN or DENV NGC replication, observations that support recent studies with DENV NGC (Carocci et al, 2015;Fraser et al, 2014). Although increases in DENV NGC viral protein production and a significant increase in secreted DENV NGC particles at 6.25 μM myriocin were observed (Fig.…”

Identification and Characterization of a Novel Broad-Spectrum Virus Entry Inhibitor

“…Viruses were titrated by plaque assay on Vero cells. DV2 and PV1 were grown as described elsewhere (25).…”

“…Plaque assays were performed as previously described (25,26). For flow cytometry, cells were harvested at 16 h postinfection, fixed with 4% paraformaldehyde, and permeabilized with 0.5% bovine serum albumin (BSA) and 0.05% saponin in phosphate-buffered saline (PBS), followed by incubation with the SA02 mouse monoclonal antibody (2 g ml Ϫ1 ; clone SA02-BG12; catalog number NR-2573; BEI Resources) specific for the JUNV nucleoprotein (NP) and coupled to Alexa Fluor 488 or Alexa Fluor 647.…”

Modification of the Host Cell Lipid Metabolism Induced by Hypolipidemic Drugs Targeting the Acetyl Coenzyme A Carboxylase Impairs West Nile Virus Replication

“…To build an adequate microenvironment to support viral replication and particle biogenesis, flaviviruses rearrange host cell lipid metabolism by promoting the synthesis and accumulation of specific cellular lipids (i.e., fatty acids, glycerophospholipids [GPLs], sphingolipids [SLs], and cholesterol) (8-15). This makes the pharmacological manipulation of cellular lipids an attractive antiviral strategy against WNV and related flaviviruses (13,14,16,17).The first steps of lipid biogenesis involve the synthesis and elongation of fatty acids, which provide the building blocks for the synthesis of more-complex lipids. Hence, fatty acid synthesis and elongation have become key targets for antiviral therapy (13,18,19).…”

“…The replication of the viral genomic RNA and flavivirus nascent virion assembly take place in modified membranes from the endoplasmic reticulum (4)(5)(6)(7). To build an adequate microenvironment to support viral replication and particle biogenesis, flaviviruses rearrange host cell lipid metabolism by promoting the synthesis and accumulation of specific cellular lipids (i.e., fatty acids, glycerophospholipids [GPLs], sphingolipids [SLs], and cholesterol) (8)(9)(10)(11)(12)(13)(14)(15). This makes the pharmacological manipulation of cellular lipids an attractive antiviral strategy against WNV and related flaviviruses (13,14,16,17).…”