Narciclasine restricts pseudorabies virus replication in vitro and in vivo and has potential broad-spectrum antiviral activity.

Plant-derived natural compounds hold significant potential in antiviral drug development, characterized by their diverse and broad-spectrum against multiple viral pathogens. Current evidence indicates that these compounds not only interfere with critical stages of the viral life cycle, but also modulate host immune responses. Antiviral potential of narciclasine against several RNA viruses has been documented, but its inhibitory activity against pseudorabies virus (PRV) remains unexplored. In this study, we systematically evaluated the antiviral activity of narciclasine in vitro and in vivo. The results demonstrated that narciclasine significantly inhibited PRV proliferation in vitro and in vivo. Meanwhile, we found that narciclasine interfered with critical stages of the PRV life cycle, such as viral replication and release. In addition, narciclasine significantly improved the survival rate of PRV-infected mice and reduced viral loads in vivo. Furthermore, narciclasine also inhibited the replication of porcine reproductive and respiratory syndrome virus (PRRSV), vesicular stomatitis virus (VSV) and porcine epidemic diarrhea virus (PEDV) in vitro, which preliminary observations suggesting that narciclasine may have a potential broad-spectrum antiviral activity. This study provided evidences for the development of narciclasine as antiviral therapeutics.