Enterovirus A71-induced glycolysis is essential for viral replication by activating PI3K/Akt pathway

Enterovirus A71 (EV-A71), an obligate intracellular acellular microbe, depends entirely on host cellular metabolism to accomplish viral replication. Glycolysis is a glucose metabolic pathway that generates adenosine triphosphate (ATP) and other intermediates that activate other metabolic pathways. However, the role of glycolysis in EV-A71 replication remains unknown. In this study, we systematically investigated the role and regulation of glycolysis in human tonsillar epithelial cells (HTECs) during EV-A71 infection. Concentration of glucose was decreased, the glucose-6-phosphate (G6P) level and lactate production were increased with upregulating the glucose transporter1 (Glut1) expression in EV-A71-infected HTECs. Moreover, cellular metabolism, including glycolysis, pentose phosphate pathway (PPP), tricarboxylic acid (TCA) cycle, and cellular respiration were activated. PI3K/Akt pathway was also activated by EV-A71. Concentration of glucose was significantly increased but concentrations of G6P and lactate were significantly decreased along with decreased Glut1 protein level, and EV-A71 replication was also significantly suppressed when the glycolysis was inhibited by 2-deoxy-D-glucose (2DG) and sodium oxamate (Oxamate) treatments. A time-of-addition assay revealed that glycolysis regulated EV-A71 replication at the early (attachment/entry) and late (release) stages of the EV-A71 life cycle. Addition of glucose or lactate experiments showed too low or too high concentrations of glucose and excessive lactate impaired EV-A71 replication by decreasing Glut1 expression to inhibit glycolysis. Inhibition of oxidative phosphorylation (OXPHOS) also decreased EV-A71 replication. Finally, PI3K/Akt pathway inhibition severely reduced EV-A71 replication and G6P production. Therefore, these findings indicate that EV-A71 alters the host cellular metabolism to facilitate viral replication by exploiting glycolysis via the PI3K/Akt pathway, thereby providing a novel insight into the interaction between EV-A71 and host cells.