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

## TL;DR

PRRSV degrades STING to activate HK2-mediated glycolysis, supporting its replication in pig cells.

## Contribution

PRRSV exploits the STING-HK2 axis to enhance glycolysis and promote viral replication.

## Key findings

- PRRSV infection reduces STING levels and increases HK2 expression, activating glycolysis.
- STING knockdown boosts HK2 activity and viral replication, while STING overexpression suppresses it.
- HK2 overexpression alone promotes viral replication, confirming its role downstream of STING.

## Abstract

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.