Infectious bursal disease virus VP3 triggers NLRP3 inflammasome activation via VDAC-mediated mitochondrial DNA release

Mitochondria play central roles in regulating innate immune responses, particularly in inflammatory processes. In response to viral infection, mitochondria can initiate processes such as mitophagy, mitochondrial DNA (mtDNA) release, and apoptosis, thereby determining the fate of stressed cells. Infectious bursal disease virus (IBDV) is a highly contagious pathogen that causes typical inflammatory symptoms in chickens. However, a direct link between this inflammation and mitochondrial involvement remains to be established. Our results demonstrated that IBDV infection triggered mtDNA release, which activated the NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, leading to interleukin-1β (IL-1β) secretion. IBDV VP3 was identified as a key mediator of mtDNA release because of its interaction with the mitochondrial outer membrane protein voltage-dependent anion channel protein (VDAC). Pharmacological inhibition of VDAC oligomerization by VBIT-4 attenuated VP3-induced mtDNA release and NLRP3 inflammasome activation. The amino acids N203 and Q204 of VP3 are essential for VDAC binding and the subsequent release of mtDNA. Our findings reveal a mechanism by which IBDV activates inflammasome signaling and advance our understanding of IBDV pathogenesis. Moreover, this study provides a theoretical basis and potential therapeutic targets for the development of antiviral drugs. IBDV VP3 promotes VDAC oligomerization by enhancing the mtDNA–VDAC association, inducing mtDNA release and activating the NLRP3 inflammasome.