Antiviral properties of Penaeus monodon cyclophilin A in response to white spot syndrome virus infection in the black tiger shrimp.

Cyclophilin A (CypA) or peptidylprolyl isomerase A, plays an important role in protein folding, trafficking, environmental stress, cell signaling and apoptosis etc. In shrimp, the mRNA expression level of PmCypA was stimulated by LPS. In this study, all three types of shrimp hemocytes: hyaline cell, granulocyte and semi-granulocyte expressed the PmCypA protein. The mRNA expression level of PmCypA was found to be up-regulate to four-fold in white spot syndrome virus (WSSV) infected hemocytes at 48 h. Interestingly, PmCypA protein was only detected extracellularly in shrimp plasma at 24 h post WSSV infection. To find out the function of extracellular PmCypA, the recombinant PmCypA (rPmCypA) was produced and administrated in shrimp primary hemocyte cell culture to observe the antiviral properties. In rPmCypA-administrated hemocyte cell culture, the mRNA transcripts of WSSV intermediate early gene, ie1 and early gene, wsv477 were significantly decreased but not that of late gene, vp28. To explore the antiviral mechanism of PmCypA, the expression of PmCypA in shrimp hemocytes was silenced and the expression of immune-related genes were investigated. Surprisingly, the suppression of PmCypA affected other gene expression, decreasing of penaeidin, PmHHAP and PmCaspase and increasing of C-type lectin. Our results suggested that the PmCypA might plays important role in anti-WSSV via apoptosis pathway. Further studies of PmCypA underlying antiviral mechanism are underway to show its biological function in shrimp immunity.