Overexpression of pig selenoprotein S blocks OTA-induced promotion of PCV2 replication by inhibiting oxidative stress and p38 phosphorylation in PK15 cells

// Fang Gan 1, 2 , Zhihua Hu 1, 2 , Yu Huang 1, 2 , Hongxia Xue 1,2 , Da Huang 1, 2 , Gang Qian 1, 2 , Junfa Hu 1, 2 , Xingxiang Chen 1, 2 , Tian Wang 3 , Kehe Huang 1, 2 1 College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, Jiangsu Province, China 2 Institute of Nutritional and Metabolic Disorders in Domestic Animals and Fowls, Nanjing Agricultural University, Nanjing 210095, Jiangsu Province, China 3 College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, Jiangsu Province, China Correspondence to: Kehe Huang, e-mail: khhuang@njau.edu.cn Tian Wang, e-mail: tianwangnjau@163.com Keywords: overexpression of selenoprotein S, ochratoxin A, porcine circovirus type 2, oxidative stress, p38 signaling pathway Received: November 16, 2015 Accepted: February 20, 2016 Published: March 01, 2016 ABSTRACT Porcine circovirus type 2 (PCV2) is the primary cause of porcine circovirus disease, and ochratoxin A (OTA)-induced oxidative stress promotes PCV2 replication. In humans, selenoprotein S (SelS) has antioxidant ability, but it is unclear whether SelS affects viral infection. Here, we stably transfected PK15 cells with pig pCDNA3.1-SelS to overexpress SelS. Selenium (Se) at 2 or 4 μM and SelS overexpression blocked the OTA-induced increases of PCV2 DNA copy number and infected cell numbers. SelS overexpression also increased glutathione (GSH), NF-E2-related factor 2 (Nrf2) mRNA, and γ-glutamyl-cysteine synthetase mRNA levels; decreased reactive oxygen species (ROS) levels; and inhibited p38 phosphorylation in PCV2-infected PK15 cells, regardless of OTA treatment. Buthionine sulfoximine reversed all of the above SelS-induced changes. siRNA-mediated SelS knockdown decreased Nrf2 mRNA and GSH levels, increased ROS levels, and promoted PCV2 replication in OTA-treated PK15 cells. These data indicate that pig SelS blocks OTA-induced promotion of PCV2 replication by inhibiting the oxidative stress and p38 phosphorylation in PK15 cells.