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

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. © 2015 kao et al.