7-GTDF from Archidendron clypearia extract inhibits PRRSV entry and interacts with the CD163 receptor

BACKGROUND: Porcine reproductive and respiratory syndrome virus (PRRSV) poses a major threat to global swine production, with no clinically approved specific therapeutics. Archidendron clypearia (AC), a medicinal plant traditionally used for human upper respiratory infections, exhibits broad-spectrum antiviral activity. This study systematically evaluated the antiviral efficacy of AC against PRRSV, elucidated its pharmacodynamic material basis through comprehensive chemical profiling, and explored the targeted molecular mechanisms of its core active component, 7-GTDF. RESULTS: Screening of 30 herbal ethanol extracts based on a PRRSV-EGFP fluorescence phenotype identified AC as possessing significant anti-PRRSV activity. In Marc-145 cells and porcine alveolar macrophages (PAMs), AC inhibited the replication of PRRSV-Li11 and PRRSV-CHR6 at both the mRNA and protein levels. Time-of-addition assays indicated that AC acts by inactivating the virus and interfering with early infection stages. Phytochemical analysis identified 40 constituents in AC, with 7-O-galloyltricetiflavan (7-GTDF) quantified via high-performance liquid chromatography (HPLC) as the predominant compound, accounting for 37.59% of the total peak area. Network pharmacology combined with experimental validation demonstrated that AC suppresses the PRRSV-induced overexpression of TNF-α, IL-1β, and IL-6 in PAMs by modulating the TLR4/NF-κB signaling pathway. Subsequent screening of the primary compounds in AC revealed that 7-GTDF exhibits significant anti-PRRSV activity. Molecular docking and molecular dynamics simulations indicated a stable interaction between 7-GTDF and the host CD163 receptor. Finally, cellular thermal shift assay (CETSA) confirmed this target engagement, demonstrating that 7-GTDF binds to the CD163 receptor and reduces its thermal stability. CONCLUSIONS: These data indicate that AC and its constituent 7-GTDF inhibit PRRSV infection through mechanisms involving CD163 targeting and inflammatory pathway modulation. These findings provide a pharmacological basis for evaluating AC as a potential antiviral candidate in swine health management.