Ebselen inhibits PRRSV replication by activating the TRIM16/SQSTM1-KEAP1-NRF2-mediated oxidative stress response pathway.

Porcine reproductive and respiratory syndrome virus (PRRSV) remains a significant pathogen in swine, causing major economic losses globally, with few antiviral treatment options available. Ebselen, a synthetic organoselenium compound known for its antioxidant, was explored for its potential to inhibit PRRSV replication. Our findings suggest that Ebselen significantly reduced viral RNA and protein levels across multiple PRRSV strains in a dose-dependent manner. Time-of-addition assays revealed that Ebselen primarily interferes with viral biosynthesis phase, though it does not inhibit the viral 3C-like protease (nsp4) directly. Transcriptomic profiling and biochemical assays indicated that Ebselen activates the NRF2 antioxidant response pathway by upregulating TRIM16 and SQSTM1, which disrupt KEAP1-NRF2 interactions, thereby stabilizing NRF2. This leads to increased expression of NRF2-regulated antioxidant enzymes and mitigation of PRRSV-induced oxidative stress. Moreover, Ebselen exhibited anti-inflammatory effects by reducing proinflammatory cytokine production. In vivo challenge experiments further showed that Ebselen treatment significantly decreased pulmonary viral loads and alleviated lung histopathological damage. These findings support potential of Ebselen as a host-targeted antiviral strategy, highlighting its dual role in managing oxidative stress and inflammation, offering a promising approach to combat PRRSV.