Honokiol Inhibits Porcine Reproductive and Respiratory Syndrome Virus Proliferation by Targeting Viral RNA Polymerase

Porcine reproductive and respiratory syndrome (PRRS) is a highly contagious swine disease and poses a severe economic burden to the global swine industry. Owing to the inadequacy of current prevention and control measures, developing effective antiviral strategies for preventing PRRS epidemics is imperative. Honokiol (HNK) is a bioactive component of the dietary supplement magnolia extract. Here, we demonstrated that HNK exhibited potent antiviral effects against different PRRSV strains in vitro. Mechanistically, HNK was shown to interfere with PRRSV replication rather than attachment, internalization, or release. HNK was further determined to target PRRSV RNA-dependent RNA polymerase to impair viral genomic RNA synthesis. In addition, HNK was found to decrease PRRSV-triggered inflammatory responses. More importantly, HNK was revealed to reduce viral loads and alleviate lung damage in vivo. This study highlights the potential of HNK as an inhibitor of PRRSV and provides novel insights into its antiviral properties.