Molecular cloning and functional characterisation of duck (Anas platyrhynchos) tumour necrosis factor receptor-associated factor 3.

1. Tumour necrosis factor receptor-associated factor 3 (TRAF3) is a key regulator of innate immunity and acquired immunity, and has a salient anti-viral role.2. In this experiment, the duck TRAF3 (DuTRAF3) gene was cloned according to the Anas platyrhynchosTRAF3 sequence to explore its function. The TRAF3 open reading frame contains 1704 bp that encode a protein of 567 amino acids, which contain a RING finger domain, two zinc finger motifs, a coiled-coil region, and a MATH domain.3. Reverse transcription-polymerase chain reaction showed that DuTRAF3 was expressed in all the examined tissues, with a comparatively higher expression in the spleen and brain tissues.4. In HEK293T cells, DuTRAF3 overexpression resulted in a significantly increased NF-kappa B activity and interferon (IFN)-beta promoter activation.5. Following resiquimod (R848) and poly(I:C) stimulation of duck peripheral blood mononuclear cells (PBMCs), the expressions of TRAF3 and IFN-beta were significantly upregulated; in addition, following R848 stimulation, the mRNA levels of IL-6, IL-8 and IL-10 were also significantly upregulated. After infection with the Newcastle Disease Virus LaSota vaccine strain, the mRNA levels of IL-6 and IL-10 were significantly upregulated, while that of TRAF3 was downregulated.6. These results suggest that DuTRAF3 has an important role to play in innate antiviral immune responses.