Grass Carp Prx 3 Elevates Host Antioxidant Activity and Induces Autophagy to Inhibit Grass Carp Reovirus (GCRV) Replication

Peroxiredoxins are a family of antioxidant proteins that protect cells from oxidative damage caused by reactive oxygen species (ROS). Herein, the peroxiredoxin 3 gene from grass carp (Ctenopharyngodon idellus), named CiPrx3, was cloned and analyzed. The full-length cDNA of CiPrx3 is 1068 bp long, with a 753 bp open reading frame (ORF) that contains a thioredoxin-2 domain, two peroxiredoxin signature motifs, and two highly conserved cysteine residues. CiPrx3 was ubiquitously expressed in all the tested tissues, while its expression level was altered significantly after exposure to grass carp reovirus (GCRV) and pathogen-associated molecular patterns (PAMPs). CiPrx3 was localized in the mitochondria of transfected cells and concentrated in the nucleus after poly (I:C) treatment. Transformation of CiPrx3 into Escherichia coli enhanced host resistance to H(2)O(2) and heavy metals. Purified recombinant CiPrx3 proteins could protect DNA against oxidative damage. Overexpression of CiPrx3 in fish cells reduced intracellular ROS, increased cell viability, and decreased cell apoptosis caused by H(2)O(2) stimulation and GCRV infection. Further study indicated that CiPrx3 induced autophagy to inhibit GCRV replication in fish cells. Collectively, these results imply that grass carp Prx3 elevates host antioxidant activity and induces autophagy to inhibit GCRV replication.