Japanese Encephalitis Virus Nonstructural Protein NS5 Interacts with Mitochondrial Trifunctional Protein and Impairs Fatty Acid β-Oxidation

Abstract

Infection with Japanese encephalitis virus (JEV) can induce the expression of pro-inflammatory cytokines and cause acute encephalitis in humans. β-oxidation breaks down fatty acids for ATP production in mitochondria, and impaired β-oxidation can induce pro-inflammatory cytokine expression. To address the role of fatty-acid β-oxidation in JEV infection, we measured the oxygen consumption rate of mock- and JEV-infected cells cultured with or without long chain fatty acid (LCFA) palmitate. Cells with JEV infection showed impaired LCFA β-oxidation and increased interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) expression. JEV nonstructural protein 5 (NS5) interacted with hydroxyacyl-CoA dehydrogenase α and β subunits, two components of the mitochondrial trifunctional protein (MTP) involved in LCFA β-oxidation, and NS5 proteins were detected in mitochondria and co-localized with MTP. LCFA β-oxidation was impaired and higher cytokines were induced in cells overexpressing NS5 protein as compared with control cells. Deletion and mutation studies showed that the N-terminus of NS5 was involved in the MTP association, and a single point mutation of NS5 residue 19 from methionine to alanine (NS5-M19A) reduced its binding ability with MTP. The recombinant JEV with NS5-M19A mutation (JEV-NS5-M19A) was less able to block LCFA β-oxidation and induced lower levels of IL-6 and TNF-α than wild-type JEV. Moreover, mice challenged with JEV-NS5-M19A showed less neurovirulence and neuroinvasiveness. We identified a novel function of JEV NS5 in viral pathogenesis by impairing LCFA β-oxidation and inducing cytokine expression by association with MTP.

Activation of the RLR/MAVS Signaling Pathway by the L Protein of Mopeia Virus

“…In recent years, viral RdRp proteins have also been reported to participate in multiple processes other than RNA synthesis. For example, in nearly all flaviviruses, NS5, the flaviviral RdRp protein, can inhibit pathways associated with IFN-I induction or signaling (52,53), while the Japanese encephalitis virus (JEV) NS5 protein can interact with the mitochondrial trifunctional protein and impairs fatty acid ␤-oxidation (54). Studies since the 1990s have indicated that expression of viral RdRp can activate the immune system and confer resistance to viral infection on plant cells (55)(56)(57).…”

Mitochondria Targeted Viral Replication and Survival Strategies—Prospective on SARS-CoV-2

“…HCV-induced loss of mitochondrial function also results in HIF-1α stabilization and a shift to glycolysis ( Ripoli et al, 2010 ). Similarly, Sindbis virus impairs both Complex I and II-linked respiration following replication, resulting in cell death ( Saks et al, 2012 ), while the Japanese Encephalitis Virus (JEV) protein NS5 disrupts β-oxidation through its interaction with hydroxyacyl-CoA dehydrogenase, thereby promoting virulence ( Khromykh et al, 2015 ). Interestingly, transcriptome profiling of MERS and SARS-CoV-infected bronchial epithelial cells also suggested a potential downregulation of the Complex I subunit NDUFA10 ( Guzzi et al, 2020 ).…”

Stealing the Keys to the Kitchen: Viral Manipulation of the Host Cell Metabolic Network

“…In addition to targeting fatty acid biosynthesis, viruses have been found to target the reverse catabolic process, fatty acid oxidation. HCMV and the Japanese encephalitis virus (JEV) inhibit fatty acid oxidation by targeting the mitochondrial trifunctional protein (MTP) which catalyzes fatty acid oxidation 33 , 34 . JEV inhibits MTP through its NS5 protein [33] , while HCMV redirects the cellular viperin protein to inhibit MTP [34] .…”

“…HCMV and the Japanese encephalitis virus (JEV) inhibit fatty acid oxidation by targeting the mitochondrial trifunctional protein (MTP) which catalyzes fatty acid oxidation 33 , 34 . JEV inhibits MTP through its NS5 protein [33] , while HCMV redirects the cellular viperin protein to inhibit MTP [34] . In contrast to these viruses that inhibit fatty acid oxidation, HCV infection requires fatty acid oxidation for its replication, which again highlights that certain aspects of viral metabolic manipulation are virus specific [35] .…”