RESUMO
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.
Assuntos
Proteínas Adaptadoras de Sinalização CARD , Infecções por Vírus de DNA/imunologia , Proteínas de Peixes , Tetraodontiformes , Sequência de Aminoácidos , Animais , Sequência de Bases , Proteínas Adaptadoras de Sinalização CARD/química , Proteínas Adaptadoras de Sinalização CARD/genética , Proteínas Adaptadoras de Sinalização CARD/isolamento & purificação , Proteínas Adaptadoras de Sinalização CARD/metabolismo , Citoplasma , Proteínas de Peixes/química , Proteínas de Peixes/genética , Proteínas de Peixes/isolamento & purificação , Proteínas de Peixes/metabolismo , Genes Reporter , Células HEK293 , Humanos , Imunidade Inata , Interferons/metabolismo , Iridoviridae/imunologia , Lipopolissacarídeos/imunologia , Dados de Sequência Molecular , NF-kappa B/imunologia , NF-kappa B/metabolismo , Poli I-C/imunologia , Análise de Sequência de DNA , Análise de Sequência de Proteína , Fator 3 Associado a Receptor de TNF/imunologia , Fator 3 Associado a Receptor de TNF/metabolismo , Tetraodontiformes/imunologia , Tetraodontiformes/metabolismo , Tetraodontiformes/virologiaRESUMO
Infectious spleen and kidney necrosis virus (ISKNV) is the type species of the genus Megalocytivirus, family Iridoviridae. We have previously established a high mortality ISKNV infection model of zebrafish (Danio rerio). In this study, a nonlethal Tetraodon nigroviridis model of ISKNV infection was established. ISKNV infection did not cause lethal disease in Tetraodon but could infect almost all the organs of this species. Electron microscopy showed ISKNV particles were present in infected tissues. Immunofluorescence and quantitative real-time PCR analysis showed that nearly all the virions and infected cells were cleared at 14 d postinfection. The expression profiles of interferon-γ and tumor necrosis factor-α gene in response to ISKNV infection were significantly different in Tetraodon and zebrafish. The establishment of the nonlethal Tetraodon model of ISKNV infection can offer a valuable tool complementary to the zebrafish infection model for studying megalocytivirus disease, fish immune systems, and viral tropism.
Assuntos
Infecções por Vírus de DNA/veterinária , Modelos Animais de Doenças , Doenças dos Peixes/virologia , Iridoviridae/fisiologia , Tetraodontiformes , Animais , Infecções por Vírus de DNA/imunologia , Infecções por Vírus de DNA/mortalidade , Infecções por Vírus de DNA/virologia , Doenças dos Peixes/imunologia , Doenças dos Peixes/mortalidade , Interferon gama/imunologia , Iridoviridae/genética , Tetraodontiformes/virologia , Fator de Necrose Tumoral alfa/imunologia , Peixe-Zebra/imunologia , Peixe-Zebra/virologiaRESUMO
In April 2004 white nodular lesions were found on the fins of whitespotted puffer Arothron hispidus (Linnaeus). Diagnostic studies were carried out to confirm the disease using light and electron microscopy, histochemical methods and PCR. The results revealed that the nodules were composed of giant cells up to 400 microm in diameter. These cells were surrounded by a periodic acid-Schiff (PAS)-positive hyaline capsule containing dot-shaped, Feulgen-positive inclusion bodies in the cytoplasm and an irregular nucleus. Numerous virus particles 200 nm in diameter and with hexagonal profiles were observed in the cytoplasm. These features were consistent with those of lymphocystis disease. Additionally, based on the gene sequences of major capsid protein (MCP) of lymphocystis disease virus (LCDV) from Japanese flounder Paralichthys olivaceus, 2 pair primers were designed; after a nested PCR was performed for detection of LCDV in A. hispidus, a positive amplified product was obtained showing the presence of LCDV. Therefore, the white nodules were the lymphocystis lesions caused by LCDV infection and A. hispidus was demonstrated to be a new host for LCDV.
