PHB1 and PHB2 positively regulate IFN-β production by targeting MAVS in ducks.

PHB1 and PHB2, two subunits of the mitochondrial prohibitin complex, are critical regulators of antiviral innate immunity. Ducks, as natural reservoirs for RNA viruses, exhibit unique antiviral mechanisms. RIG-I is a key receptor for recognizing RNA viruses in ducks. However, the roles of PHB1 and PHB2 in the RIG-I-MAVS-IFN-β signaling pathway remain unclear. Here, we characterized the duPHB1 and PHB2 structure and functional domains, which contains similar N-terminal transmembrane domain, PHB domain and coil-coiled C-terminal domain, revealing high conservation with avian and mammalian orthologs. Both genes were ubiquitously expressed in duck tissues, with elevated levels in immune-related organs (e.g., pancreas, thymus) and tissues with high metabolic activity and tissue regeneration ability (e.g., heart, liver and muscle) post-NDV infection. We next sought to investigate the functional roles by which duPHB1 and duPHB2 triggered antiviral innate immune response. Overexpression of duPHB1/2 in DEFs enhanced MAVS activation and IFN-β production upon 5'ppp dsRNA stimulation, while siRNA-mediated knockdown suppressed these effects. Co-transfection of duPHB1 and duPHB2 synergistically amplified MAVS-dependent IFN-β induction. Crucially, MAVS depletion abolished PHB1/2-mediated IFN-β upregulation, demonstrating their dependence on MAVS signaling. Our findings establish duPHB1/2 as key regulators of mitochondrial-mediated antiviral responses in ducks, providing insights into avian innate immunity.