RESUMO
N-myc and STAT interactor (NMI) is an interferon-induced protein, which plays a variety of biological functions by participating in signal transduction and transcriptional activation, it has been reported to regulate antiviral response of different viruses in many species. However, the role of NMI in ducks during Duck Tembusu Virus (DTMUV) infection is completely unknown. In order to reveal whether duck NMI (duNMI) is involved in the antiviral response in the process of DTMUV infection and its role, we cloned and identified duNMI gene, and conducted sequence analysis of duNMI, the open reading frame region of duNMI gene is 1,137 bp, encoding 378 amino acid residues (aa), including 3 domains, Coiled-coil domain (22-126aa), NMI/IFP 35 domain 1 (NID1) domain (174-261aa) and NMI/IFP 35 domain 2 (NID2) domain (272-360aa). Analysis of tissue distribution of duNMI in 7-day-old ducks shows that the expression of duNMI is the highest in harderian gland, followed by small intestine and pancreas. Subsequently, we found that mRNA level of duNMI increases significantly after DTMUV stimulation, and overexpression of duNMI inhibits DTMUV replication in a dose-dependent manner. Besides, duNMI inhibits the transcriptional activity of IFN-I related cytokines. Specifically, we confirmed that duNMI interacts with duck regulatory factor 7 (duIRF7) through NID1 and NID2 domains and inhibit its expression and activated-IFN-ß. These results support that duNMI is an inhibitor of antiviral innate immune response in the process of DTMUV infection, which will provide a theoretical basis for the prevention of DTMUV infection.
RESUMO
The tumor necrosis factor (TNF) receptor-associated factor 3 (TRAF3) is a key signaling molecule in the retinoic acid-inducible gene I (RIG-I) signaling pathway and plays an important role in host innate immune regulation. The function of TRAF3 has been extensively studied in mammals, however, the role of TRAF3 in ducks remains unclear. In order to reveal the function of duck TRAF3 (duTRAF3) in the innate immune response induced by virus infection, the TRAF3 homologue of mallard (Anas platyrhynchos) has been cloned and the function of duTRAF3 is investigated in this study. We sequenced duTRAF3 and found that the open reading frame (ORF) region of duTRAF3 is 1704 bp long and encodes 567 amino acids (aa), which has a similar functional domain to the mammalian gene. Analysis of tissue distribution of duTRAF3 in 7-day-old ducks showed that the expression of duTRAF3 was highest in harderian gland, followed by heart and lung. Subsequently, duck Tembusu virus (DTMUV) has been shown to enhance duTRAF3 expression, and overexpression of duTRAF3 inhibits DTMUV replication in a dose-dependent manner. In addition, duTRAF3 activates the transcriptional activity of IFN-α and its downstream interferon-stimulating genes (ISGs) induced after DTMUV infection. In this process, DTMUV non-structural (NS) protein 5 resists this innate immune process by interacting with TRAF3 and inhibiting TRAF3 expression. These data support the conclusion that duTRAF3 is an antiviral protein that plays a key role in the defense against DTMUV invasion. These results lay a theoretical foundation for developing new anti-DTMUV strategies.
