The Cytopathogenic BVDV Core Protein Binds with ASC-Enhance the Assembly of Inflammasome Complex and GSDMD-Mediated Pyroptosis.

Bovine viral diarrhea virus (BVDV) infection is associated with inflammatory responses, but the mechanisms underlying inflammasome activation remain unclear. In this study, Madin-Darby bovine kidney (MDBK) cells were used to compare the inflammatory responses induced by the cytopathogenic NADL strain and the non-cytopathogenic TC strain. Both strains significantly increased IL-1β and IL-18 production and promoted NLRP3 inflammasome assembly, indicating activation of upstream inflammasome signaling. However, only the NADL strain markedly induced Gasdermin D (GSDMD) cleavage, membrane pore formation, lactate dehydrogenase release, and pyroptotic cell death. Further mechanistic analyses demonstrated that the NADL core protein C interacted with the inflammasome adaptor ASC, thereby facilitating NLRP3 inflammasome assembly and enhancing inflammatory cytokine secretion. Silencing ASC significantly impaired inflammasome activation and pyroptosis induced by protein C, confirming its essential role in this process. Collectively, these findings demonstrate that the cytopathogenic BVDV NADL strain activates ASC-dependent NLRP3 inflammasome signaling and GSDMD-mediated pyroptosis through its core protein C, providing a molecular explanation for the distinct inflammatory responses and pathogenic outcomes associated with different BVDV biotypes.