One of the most powerful innate immune responses against virus is mediated by type I interferon (IFN). We searched the presence of genes involved in the IFN pathway in European sea bass (Dicentrarchus labrax) and evaluated their regulation by nodavirus (VNNV) infection in brain and gonad of infected specimens as well as in a new sea bass cell line (DLB-1), derived from brain. We identified genes encoding MDA5 (Melanoma Differentiation Associated gene 5), LGP2 (Laboratory of Genetics and Physiology 2), MAVS (mitochondrial antiviral signaling protein), TRAF3 (tumour necrosis factor receptor-associated factor 3), TANK (TRAF family member-associated NF-kB activator), TBK1 (TANK binding kinase 1), IRF3 (IFN regulatory factor 3), IRF7 and PKR (dsRNA dependent protein kinase receptor). Thus, in the susceptible species European sea bass, we found that mda5, lgp2 or irf3 gene expression in brain was up-regulated by VNNV infection, as ifn, mx and pkrgenes at different sampling times. Strikingly, most of the genes were up-regulated in gonad. In DLB-1 cell line, most of them were up-regulated by VNNV infection but in lower level than the induction provoked by poly I:C treatment. Further studies will be conducted to characterize the IFN pathway in sea bass and their role in the immune response against VNNV
