PEG-PLGA Co-Loaded Baicalin Mitigates Bovine Viral Diarrhea Virus-Induced Oxidative Stress and Inflammatory Responses Through Modulation of Autophagy and Attenuation of the NLRP3/Pyroptosis Regulatory Axis.

Bovine viral diarrhea virus (BVDV), a globally persistent pathogen, causes bovine viral diarrhea-mucosal disease (BVD-MD), a contagious bovine disease posing significant pressures on both public health and economic development. Baicalin (BA), a flavonoid derived from Scutellaria baicalensis, exhibits broad antiviral activities but suffers from poor aqueous solubility and low bioavailability, limiting its therapeutic potential against BVDV. To address this limitation, we developed BA-loaded poly (ethylene gly-col)-poly (lactic-co-glycolic acid) (PEG-PLGA) nanoparticles (BA-PEG-PLGA NPs). While autophagy and NLRP3 inflammasome activation have been individually implicated in viral pathogenesis, their functional crosstalk during BVDV infection remains uncharacterized. Herein, we evaluated the antiviral efficacy of BA-PEG-PLGA NPs through integrated in vitro and in vivo experiments. We employed quantitative polymerase chain reaction (qPCR), transcriptome sequencing, Western blot analysis, immunofluorescence microscopy, flow cytometry, and enzyme-linked immunosorbent assay (ELISA) to investigate the mechanisms by which BA and BA-PEG-PLGA NPs combat bovine viral diarrhea virus (BVDV) infection. We found that both free BA and BA-PEG-PLGA NPs effectively attenuated BVDV replication in vitro and in vivo; notably, the nano-formulation exhibited superior efficacy. Mechanistically, BA and its nano-formulation restored autophagy homeostasis, suppressed ROS overproduction, and blocked NLRP3 inflammasome activation and pyroptotic cell death effects comparable to the specific NLRP3 inhibitor MCC950. These findings establish the autophagy-NLRP3/pyroptosis axis as a critical pathogenic mechanism in BVDV infection and reveal that nano-formulated baicalin represents an antiviral strategy by coordinately targeting this axis. This work not only provides a translatable nanomedicine approach for BVDV control but also expands the mechanistic understanding of flavonoid-based interventions in viral inflammatory diseases.