Foot-and-mouth disease virus regulates glycolysis through autophagy to drive viral replication in vivo and in vitro.

Viruses, lacking an intrinsic metabolic network, exploit host cell metabolism in order to hijack resources for their own replication. However, the regulatory relationship between foot-and-mouth disease virus (FMDV) and energy metabolism remains incompletely elucidated. Here, metabolomic analysis was performed on PK-15 cells and tonsils infected with FMDV. Metabolites involved in glycolysis were significantly upregulated, whereas metabolites associated with the tricarboxylic acid (TCA) cycle were markedly downregulated in vivo and in vitro, which indicated that FMDV induced reprogramming of host cell energy metabolism, shifting it from oxidative phosphorylation (OXPHOS) to glycolysis. Furthermore, FMDV infection promoted glucose uptake and its subsequent utilization in FMDV-infected PK-15 cells, facilitating viral replication. Mechanistically, on the one hand, FMDV infection activated the AKT-MTOR-dependent macroautophagy/autophagy pathway to suppress the expression of OTUD4 (OTU deubiquitinase 4), upregulating HK2 (hexokinase 2) to facilitate glycolysis. On the other hand, FMDV infection decreased the level of mitochondrial SIRT3 (sirtuin 3) through PINK1-PRKN-dependent mitophagy, leading to the increase of HIF1A (hypoxia inducible factor 1 subunit alpha), HK2, phosphofructokinase 1 (PFK1), and PKM/PKM2 (pyruvate kinases M1/2), promoting glycolysis. Overall, this study elucidates how FMDV modulates glycolysis through two different autophagic pathways, which would contribute to our understanding of how the autophagy-glycolysis axis regulates viral replication, providing new avenues for developing antiviral strategies targeting metabolism.Abbreviations: 3-MA: 3-methyladenine; ACTB: actin beta; ATG: autophagy related; CQ: chloroquine; dpi: days post-infection; EV71: enterovirus 71; FMDV: foot-and-mouth disease virus; HK2: hexokinase 2; HIF1A: hypoxia inducible factor 1 subunit alpha; hpt: hours post-transfection; MOI: multiplicity of infection; MTOR: mechanistic target of rapamycin kinase; OTUD4: OTU deubiquitinase 4; OXPHOS: oxidative phosphorylation; PFK1: phosphofructokinase 1; PFKFB3: 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3; PKM/PKM2: pyruvate kinase M1/2; SIRT3: sirtuin 3; siRNA: small interfering RNA; TCID50: 50% tissue culture infectious doses; TCA: tricarboxylic acid; TUNEL: terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling; WT: wild type.