Thioredoxin of Litopenaeus vannamei facilitated white spot syndrome virus infection.

Thioredoxin (TRX), a major intracellular antioxidant, has a wide range of biological functions. It was up-regulated and targeted by WSSV. However, the relevance of TRX with WSSV infection and signaling pathway remains largely unknown. Sequence analysis indicated that TRX might interact with the WSSV030 (VP362) and WSSV454 (thymidine kinase-thymidylate kinase, TK-TMK) of WSSV. In this study, TRX, VP362 and TK-TMK were expressed and the interaction of TRX with VP362 or TK-TMK was investigated. Furthermore, how TRX affect the process of WSSV infection and the gene transcription of inhibitor of nuclear factor kappa-B kinase (IKK), a p38 mitogen-activated protein kinase (LvP38) and signal transducer and activator of transcription (STAT) in the hemocytes and hepatopancreas was explored. Far-western blot and enzyme-linked immuno assay (ELISA) results showed that TRX interacted with VP362 and TK-TMK. The mRNA expressions of IKK, LvP38 and STAT were significantly affected by the over-presence of TRX of Litopenaeus vannamei. Neutralization experiment in vivo indicated that TRX induced the transcription expression of VP28 and increased the viral copy numbers in the early stage of WSSV infection and it may attribute to the death of shrimps infected by WSSV.