Involvement of fatty acid synthase in dengue virus infection

Abstract

BackgroundThe mosquito transmitted Dengue virus (DENV) remains a significant public health problem in many tropical and subtropical countries. Increasing evidence has suggested that during the infection process cellular lipids play important roles at several stages of the replication cycle. This study sought to characterize the changes in lipid metabolism gene expression and investigated the role of one enzyme, fatty acid synthase, in DENV infection.MethodsTranscriptional profiles of genes associated with lipid metabolism were evaluated by real-time PCR after infection of different cell lines (HepG2 and HEK293T/17) and with different DENVs (laboratory adapted and low passage). Expression profiles of genes were evaluated by western blotting. A critical lipid metabolism protein, fatty acid synthase was down-regulated through siRNA and inhibited with orlistat and the effect on DENV infection determined by flow cytometry, plaque assay, western blotting and confocal microscopy.ResultsThe results showed alterations of gene transcription and expression were seen in genes variously associated with lipogenesis, lipolysis and fatty acid β-oxidation during DENV infection. Interference of fatty acid synthase with either siRNA or orlistat had marked effects on virus production, with orlistat having an EC50 value of 10.07 μM at 24 h post infection. However, non-structural protein expression was largely unaffected.ConclusionsWhile drug treatment reduced virus titer by up to 3Log10, no significant effect on DENV non-structural protein expression was observed, suggesting that fatty acid synthase acts through an effect on virion formation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12985-017-0685-9) contains supplementary material, which is available to authorized users.

Evaluation of the antiviral activity of orlistat (tetrahydrolipstatin) against dengue virus, Japanese encephalitis virus, Zika virus and chikungunya virus

“…2-4). All screening was therefore undertaken at a concentration of 100 μM of orlistat, consistent with our previous study 27 .…”

“…We have previously shown the effect of orlistat on DENV protein expression under a combined pre-and post-infection treatment protocol 27 . To determine the effect of orlistat on viral protein expression under the minimal treatment regime (pre-treatment only), cells were not pre-treated, or pre-treated with orlistat for 1 h before infection with DENV (DENV 2LAB, DENV 4LAB, DENV 2DF and DENV 4DF), ZIKV (SV0010/15) or JEV (BJ1).…”

“…In our previous study we showed the utility of orlistat as an antiviral agent against DENV 27 , however that study only investigated DENV serotypes 2 and 4. As noted earlier, flaviviruses have no RdRP proof reading activity, and as such show significant variation.…”

Perturbation of Intracellular Cholesterol and Fatty Acid Homeostasis During Flavivirus Infections

“…Another member of the Flaviviridae family, dengue, has also been reported to induce production of fatty acids (49,50). FASN and ACC1 were identified through a targeted siRNA screen as necessary factors for efficient dengue virus replication (38,51). Drugs that inhibited FASN activity resulted in a significant attenuation in virus replication (49).…”

“…This phenomenon appears to be Rab18-mediated, a member of the GTPase family that typically resides in the ER and LDs. Upon infection dengue NS3 was found to interact with Rab18, which allowed recruitment of FASN to viral replication sites, thus promoting fatty acid biosynthesis to increase their local concentration (51,52). Inhibiting FASN activity has a similar effect in mosquito cells with loss of infectious progeny virion production (53).…”