The Role of Hypoxia Inducible Factor-1 alpha (HIF-1⍺) in Human Coronavirus OC43 Infection

The importance of altering host cell metabolism for promoting infection and propagation of coronaviruses highlights the intricate play between viruses and the cells they infect (1). Upregulation of the glycolytic pathway in host cells infected with coronaviruses was observed in single-cell RNAseq, although the mechanism(s) that mediate this effect are still being investigated(2). Hypoxia-inducible factor-1 alpha (HIF-1⍺) is a transcription factor that regulates many glycolytic enzymes. Recent studies have identified SARS-CoV-2 upregulation of HIF-1⍺, which suggests it may have an important role in virus production (3, 4). However, the exact role and physiological relevance of HIF-1⍺ during viral infection is undetermined as most all studies have used pharmacological inhibitors, which can have unknown off target effects. Currently, SARS-CoV-2 is the most well studied of the betacoronaviruses especially within viral mediated modulation of host cell metabolism. In our study, we explore the relationship between HIF-1⍺ and the human betacoronavirus OC43 using a human colorectal cancer cell line, HCT116, with a targeted deletion for HIF-1⍺. We hypothesize that OC43 will upregulate glycolysis and that virion production will be diminished in the absence of HIF-1⍺. Infection of HCT-116 cells with OC43 resulted in elevated glycolysis, while the virus failed to increase this metabolic pathway in the HIF-1⍺ knockout (KO) cell line. OC43 was significantly diminished in HIF-1⍺ KO cells. To dissect the signaling pathway, we used a cell line that lacks AKT ½, which is upstream of HIF-1⍺. OC43 failed to induce HIF-1⍺ in HCT-116 cells lacking AKT1 and AKT2, suggesting that AKT signaling is a key mediator of OC43’s effects. Overall, our data demonstrate that HIF-1⍺ is critical for maximal OC43 replication within host cells.