Magnolol inhibits viral replication and enhances antiviral immune responses against porcine reproductive and respiratory syndrome virus (PRRSV) in Marc-145 cells

BackgroundPorcine reproductive and respiratory syndrome virus (PRRSV) is a pathogen that affects swine and causes substantial economic losses in the global pig industry. Despite the availability of vaccines, it remains crucial to explore innovative therapeutic strategies to control PRRSV infections. Magnolol, a bioactive compound extracted from the root and bark of Magnolia officinalis, has demonstrated broad-spectrum antiviral activity in previous studies.MethodsThe cytotoxicity of magnolol was determined by the CCK-8 method. RT-qPCR, western blot, and immunofluorescence were used to study the inhibitory effect of magnolol on PRRSV N gene and protein expression through antiviral assay and viral attachment, internalization, replication and release assays. The effect of magnolol on immune-related gene expression was analysed by RT-qPCR.ResultsWe found magnolol hinders multiple facets of the PRRSV lifecycle, encompassing the stages of viral attachment and replication. Furthermore, magnolol enhances the expression of pivotal cytokines, including interleukin-6 (IL-6), interleukin-8 (IL-8), and tumour necrosis factor-α (TNF-α), during PRRSV infection, thereby reinforcing the host cells' capacity to mount an effective antiviral defence. Additionally, it exerts inhibitory effects on PRRSV replication by upregulating the expression of a disintegrin and metalloprotease 17 (ADAM17) at both the protein and mRNA levels.ConclusionsIn this study, we provide evidence demonstrating the potent efficacy of magnolol in inhibiting PRRSV replication within Marc-145 cells. Our findings underscore the potential of magnolol as a novel antiviral agent for the PRRSV control.