The σNS protein of NDRV antagonizes TRIM59-mediated antiviral innate immune response of Cherry Valley duck.

In recent years, outbreak of the novel duck reovirus (NDRV) disease has occurred frequently in duck populations. Due to its rapid spreading, absence of effective control methods, and high treatment costs, the NDRV disease has caused huge losses to waterfowl breeding in China. As reported, four non-structural (NS) proteins are encoded by the NDRV genome, among which the σNS protein is an RNA-binding protein that can improve the stability of bound RNA by forming oligomers (Adams and Cory, 1998). Nevertheless, the mechanism by which it facilitates reovirus replication remains ambiguous. According to previous studies, the NS protein 11 of the porcine reproductive and respiratory syndrome virus (PRRSV) can interact with tripartite motif-containing 59 (TRIM59) to regulate viral infection. However, the specific role of TRIM59 in NDRV infection remains unclear. This study focused on full-length amplification of duTRIM59, the mRNA distribution of duTRIM59 in Cherry Valley duck and successive biological examinations. The homology with Anas platyrhynchos TRIM59 was 98.6 %. The mRNA distribution level of duTRIM59 showed that duTRIM59 was widely expressed in bursae and thymus of the immune organs. Nevertheless, TRIM59 comprises three domains, including the transmembrane (TM), B-box (B), and RING-finger (R) domains. It also has the activity of ubiquitin-protein ligase (E3). It has been demonstrated that NDRV replication is inhibited by TRIM59 overexpression in duck embryonic fibroblasts (DEF) cells, particularly when the R domain is intact, suggesting that the R domain plays a key role in the spreading of the NDRV virus. In contrast, NDRV infection in DEF cells increased when TRIM59 was depleted by using small interfering RNA. Moreover, the σNS protein can be co-localized with duTRIM59 and stimulate NDRV replication in DEF cells in cases of NDRV infection. This study clarifies the correlation of NDRV infection and TRIM59-mediated antiviral innate immunity, and provides a sound theoretical basis for further understanding this disease.