title: Penaeus monodon thioredoxin restores the DNA binding activity of oxidized white spot syndrome virus IE1.
abstract: OBJECTIVE
  In this study we identified viral gene targets of the important redox regulator thioredoxin (Trx), and explored in depth how Trx interacts with the immediate early gene #1 (IE1) of the white spot syndrome virus (WSSV).
  
  
  RESULTS
  In a pull-down assay, we found that recombinant Trx bound to IE1 under oxidizing conditions, and a coimmunoprecipitation assay showed that Trx bound to WSSV IE1 when the transfected cells were subjected to oxidative stress. A pull-down assay with Trx mutants showed that no IE1 binding occurred when cysteine 62 was replaced by serine. Electrophoretic mobility shift assay (EMSA) showed that the DNA binding activity of WSSV IE1 was downregulated under oxidative conditions, and that Penaeus monodon Trx (PmTrx) restored the DNA binding activity of the inactivated, oxidized WSSV IE1. Another EMSA experiment showed that IE1's Cys-X-X-Cys motif and cysteine residue 55 were necessary for DNA binding. Measurement of the ratio of reduced glutathione to oxidized glutathione (GSH/GSSG) in WSSV-infected shrimp showed that oxidative stress was significantly increased at 48 h postinfection. The biological significance of Trx was also demonstrated in a double-strand RNA Trx knockdown experiment where suppression of shrimp Trx led to significant decreases in mortality and viral copy numbers.
  
  
  CONCLUSIONS
  WSSV's pathogenicity is enhanced by the virus' use of host Trx to rescue the DNA binding activity of WSSV IE1 under oxidizing conditions.
authors.affiliation: Institute of Zoology, College of Life Science, National Taiwan University, Taipei, Taiwan, Republic of China.
authors.forename: Jiun-Yan
authors.initials: JY
authors.lastname: Huang
authors.forename: Wang-Jing
authors.initials: WJ
authors.lastname: Liu
authors.forename: Han-Ching
authors.initials: HC
authors.lastname: Wang
authors.forename: Der-Yen
authors.initials: DY
authors.lastname: Lee
authors.forename: Jiann-Horng
authors.initials: JH
authors.lastname: Leu
authors.forename: Hao-Ching
authors.initials: HC
authors.lastname: Wang
authors.forename: Mong-Hsun
authors.initials: MH
authors.lastname: Tsai
authors.forename: Shih-Ting
authors.initials: ST
authors.lastname: Kang
authors.forename: I-Tung
authors.initials: IT
authors.lastname: Chen
authors.forename: Guang-Hsiung
authors.initials: GH
authors.lastname: Kou
authors.forename: Geen-Dong
authors.initials: GD
authors.lastname: Chang
authors.forename: Chu-Fang
authors.initials: CF
authors.lastname: Lo
mesh_terms: D000818:Animals; D002460:Cell Line; D004279:DNA, Viral / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D047468:Immunoprecipitation; D033561:Penaeidae / Q000378:metabolism / Q000821:virology; D011485:Protein Binding; D013879:Thioredoxins / Q000378:metabolism*; D046848:White spot syndrome virus 1 / Q000235:genetics* / Q000472:pathogenicity*
chemical_list: D004279:DNA, Viral; D013879:Thioredoxins