Characterization of a TnMAVS protein from Tetraodon nigroviridis

A growing family of cellular proteins encoding for caspase activation and the recruitment domain (CARD) plays a crucial role in immunity by sensing viral infections and signaling antiviral immune defenses. We obtained a MAVS-like protein (named TnMAVS) from Tetradon nigroviridis, which contains a CARD domain, a pro-rich domain, and a TM domain similar to human MAVS. A fluorescence assay showed that TnMAVS was located in the cytoplasm and near by the membrane, and not the mitochondria in FHM cells. As such, it was considered as a new member of MAVS. The TnMAVS was highly expressed in the liver and muscle of T. nigroviridis. In the spleen, TnMAVS was down-regulated when the fish was treated with polyinosinic:polycytidylic acid or challenged with ISKNV, but was not affected by PGN or LPS. The dual luciferase reporter assay revealed that TnMAVS overexpression resulted in the activation of the interferon-sensitive response element and NF-κB signal pathways. In addition, a characteristic TRAF3-associated peptide PVQD was found in the TnMAVS sequence. Co-immunoprecipitation assays indicated that TnMAVS could interact with zfTRAF3 in eukaryotic cells.