Glucose and Glutamine Drive Hepatitis E Virus Replication

Abstract

Viruses have undergone evolutionary adaptations to tune their utilization of carbon sources, enabling them to extract specific cellular substrates necessary for their replication. The lack of a reliable cell culture system and a small animal model has hampered a better understanding of the underlying molecular mechanisms of replication of the genotype 1 hepatitis E virus (HEV). Our recent identification of a replicative ensemble of mutant HEV RNA libraries has allowed us to study the metabolic prerequisites of HEV replication. The initial assessments have revealed increased glucose and glutamine utilization during HEV replication. Inhibition of glycolysis and glycolysis + glutaminolysis have exhibited similar effects in reducing the levels of HEV replication. An integrated analysis of protein-metabolite pathways has suggested that HEV replication markedly altered glycolysis, the TCA cycle, and glutamine-associated metabolic pathways. Cells supporting HEV replication have shown a critical involvement of fructose-6-phosphate and glutamine utilization through hexosamine biosynthetic pathway (HBP), stimulating HSP70 expression to facilitate virus replication. Confirmation of the crucial role of HBP in supporting HEV replication comes from observations of mannose utilization and glutamine dependency. Inhibition of glycolysis and HSP70 activity, or knockdown of glutamine fructose-6-phosphate amidotransferase expression, led to a substantial reduction in HEV RNA and ORF2 expression, accompanied by a significant decrease in HSP70 levels. In conclusion, this study demonstrates that glucose and glutamine play critical roles in facilitating HEV replication.