Cloning of eIF5A from shrimp Penaeus monodon, a highly expressed protein involved in the survival of WSSV-infected shrimp

Shrimp respond to viral infection with up- and down-regulation of many critical genes. In our previous work, we showed that white spot syndrome virus (WSSV) infection of Penaeus monodon (Pm) caused cellular syntenin levels to increase. In order to further explore the signal transduction pathway of syntenin, we constructed the cDNA library of WSSV-infected shrimp and performed a yeast two-hybrid screening of the library using syntenin as bait. Here we report that syntenin specifically binds eukaryotic translation initiation factor 5A (eIF5A), a 157 amino acid polypeptide that is implicated in cell proliferation and survival. GST-pull-down assays showed the presence of specific interaction between Pm-syntenin and eIF5A. Message analyses revealed that syntenin expression remained normal when shrimp were infected with WSSV but did not show any gross signs of disease. Syntenin expression, however, increased 1.4-fold when shrimp became dead. In contrast, eIF5A expression increased markedly during the stage of WSSV infection when there were no gross signs of disease, i.e., prior to the moribund stage. At the moribund stage, eIF5A expression was down-regulated. This data suggest that syntenin and eIF5A physically interact with each other in the setting of WSSV infection and that these two molecules exhibit dynamic changes in their expression patterns as infection progresses from grossly normal, infected shrimp to full-blown phase.