Overexpression of TRIM16 Reduces the Titer of H5N1 Highly Pathogenic Avian Influenza Virus and Promotes the Expression of Antioxidant Genes through Regulating the SQSTM1-NRF2-KEAP1 Axis.

Oxidative stress plays a vital role in viral replication. Tripartite motif containing 16 (TRIM16) is involved in diverse cellular processes. However, the role of TRIM16 in oxidative stress induced by infection of the highly pathogenic H5N1 avian influenza virus (HPAIV) is unclear. We found that under conditions of H5N1 HPAIV infection, reactive oxygen species (ROS) levels in A549 cells peaked at 24 h post infection (hpi), and antioxidant genes' expression levels were down-regulated. Overexpression of TRIM16 in A549 cells resulted in a decrease in the titter of H5N1 HPAIV and led to significant up-regulation of the antioxidant genes' expression levels, which indicates that TRIM16 positively regulates the sequestosome 1/Kelch-like associated enoyl-CoA hydratase 1 protein/nuclear factor erythrocyte 2-derived 2-like 2 (SQSTM1/NRF2/KEAP1) pathway. Under basal conditions, TRIM16 led to a modification of NRF2 through an increase in K63-linked poly-ubiquitination of NRF2. Collectively, our findings provide new insight into understanding TRIM16's role in anti-oxidative stress in H5N1 HPAIV infected A549 cells.