The activation of the metabolic oxaloacetate-pyruvate axis restores influenza A virus replication during impaired glycolysis.

Abstract

Viruses strongly depend on the host cell for efficient replication and influenza A virus (IAV) amongst others also lead to remarkable changes of the host cell metabolism. The restriction of virus replication through suppression of glucose metabolism has already been described. In addition to glycolysis and glutaminolysis, viral replication also relies on the tricarboxylic acid (TCA) cycle. So far, the metabolic key intermediate of the TCA cycle, oxaloacetate (OAA), is described to enhance glycolysis and respiration flux rates under metabolic stress conditions. However, the mode of action of the metabolic fuel intermediate OAA in direct relation to influenza viral growth under strong glycolysis inhibition remains unclear. As the TCA cycle acts as a central metabolic hub linking all major metabolic pathways, the effects of OAA under glycolysis inhibition were examined in greater detail in this study. We aimed to get a better understanding of metabolic host-virus interactions and to analyze the effects of metabolic fueling intermediates on IAV replication under glycolysis inhibition. We inhibited glycolysis and supplemented IAV infected cells with the metabolic fueling intermediate OAA. Inhibition of glycolysis led to a statistically significant reduction of viral titers while OAA addition reversed the antiviral effects such as reduced viral protein accumulation, viral titers, and vRNA expression. In line with previous studies, we showed that mannose, which is closely connected to glycolysis, circumvents the virus restricting effects of glycolysis inhibition. Moreover, we demonstrated that supplementation of mannose or OAA led to a roughly comparable replication recovery under strong inhibition of glycolysis. Furthermore, mass spectrometry-based metabolomics data revealed a strong accumulation of pyruvate in OAA supplemented samples. Finally, comparing OAA and pyruvate rescuing capacities of IAV growth under glycolysis inhibition tended to show similar activities for both metabolites arguing that OAA mediated IAV rescue is achieved through its conversion to pyruvate. Summarizing, our data indicate that the TCA cycle intermediate OAA has virus supporting effects as it reversed the antiviral effects of glycolysis inhibition.