STING Degradation by PRRSV Activates HK₂-Mediated Glycolysis to Facilitate Viral Replication

Porcine reproductive and respiratory syndrome virus (PRRSV) infection relies on glycolytic reprogramming to support replication, but the mechanisms driving this metabolic shift remain poorly understood. The stimulator of interferon genes (STING), an innate immune adaptor, recently emerged as a metabolic regulator by directly binding and inhibiting hexokinase-2 (HK₂), a key rate-limiting enzyme in glycolysis. Whether PRRSV exploits the STING-HK₂ axis to unleash glycolysis for its own replication is unknown. Here we demonstrate that PRRSV infection induced STING degradation and promoted HK₂ suppression, activating glycolysis for viral replication. In PRRSV-infected Marc-145 cells, lactate production (a glycolysis marker) and HK₂ expression increased time-dependently, peaking at 48 h post-infection (hpi). Conversely, STING protein levels decreased significantly at 36 hpi and further at 48 hpi, suggesting a correlation between STING downregulation and glycolytic activation. The HK₂ inhibitor 2-deoxy-D-glucose reduced lactate production and viral load, while the glycolysis activator PS48 enhanced both. STING knockdown via siRNA increased HK₂ expression, lactate secretion, and PRRSV nucleocapsid protein levels, whereas STING overexpression suppressed these phenotypes. Co-immunoprecipitation and confocal microscopy demonstrated direct STING-HK₂ interaction and cytoplasmic co-localization, maintained during PRRSV infection. HK₂ overexpression promoted viral replication without altering STING levels, confirming HK₂ as a downstream effector. In conclusion, PRRSV-triggered degradation of STING enhances HK₂ expression, promoting lactate accumulation and accelerating viral replication. These findings suggest that the STING-HK₂ axis can act as a critical viral metabolic checkpoint and highlight targeting metabolic-immune crosstalk as a potential anti-viral strategy.