Luteolin Inhibits Bovine Viral Diarrhea Virus Replication by Disrupting Viral Internalization and Replication and...

Bovine viral diarrhea virus (BVDV) causes severe mucosal inflammation in cattle, and effective treatment options remain limited. Dysregulated activation of the NLRP3 inflammasome, driven by NF-κB and STAT3 signaling, may exacerbate disease pathogenesis, highlighting this axis as a potential therapeutic target. Although traditional Chinese medicine has shown promise in antiviral and anti-inflammatory applications, it remains unclear whether it can inhibit BVDV replication via the NF-κB/STAT3-NLRP3 pathway. The present study aimed to clarify the inhibitory effect of luteolin on bovine viral diarrhea virus (BVDV) replication, and to elucidate its underlying mechanisms from two perspectives: interference with viral internalization and replication processes, as well as regulation of the NF-κB/STAT3-NLRP3 inflammasome pathway. Collectively, this work intended to provide experimental evidence and theoretical support for the development of luteolin as a natural anti-BVDV agent. To this end, BVDV-infected MDBK cells were treated with gradient concentrations of luteolin, followed by quantification of viral load using qRT-PCR and Western blot assays. Meanwhile, the activation status of the NF-κB/STAT3-NLRP3 signaling pathway was evaluated via immunofluorescence staining and luciferase reporter gene assays. Our results demonstrate that luteolin exhibits potent dual antiviral activity against cytopathic BVDV-1m in MDBK (Madin-Darby Bovine Kidney) cells, effectively suppressing both viral replication and inflammatory responses. At non-cytotoxic concentrations, luteolin specifically inhibited the internalization and replication stages of the viral lifecycle, accompanied by reduced NS5B polymerase activity. Importantly, luteolin disrupted the NF-κB/STAT3-NLRP3 axis by suppressing phosphorylation of p65 (Ser536) and STAT3 (Ser727), downregulating NLRP3 and pro-caspase-1 expression, and inhibiting caspase-1 cleavage (p20) as well as maturation of IL-1β and IL-18. Consequently, it attenuated the overexpression of TNF-α and IL-8. To our knowledge, this is the first report of a single compound simultaneously targeting multiple stages of the BVDV lifecycle and counteracting NLRP3-mediated immunopathology, offering a strategic basis for developing flavonoid-based therapies against Flavivirus infections.