The transcription factor CEBP homolog of Penaeus vannamei contributes to WSSV replication

The cellular transcription factors are known to play important roles in virus infection. The present study cloned and characterized a transcription factor CCAAT/Enhancer-binding protein homolog from the shrimp Penaeus vannamei (designates as PvCEBP), and explored its potential functions in white spot syndrome virus (WSSV) infection. PvCEBP has an open reading frame (ORF) of 864 bp encoding a putative protein of 287 amino acids, which contained a highly C-terminal conserved bZIP domain. Phylogenetic tree analysis showed that PvCEBP was evolutionarily clustered with invertebrate CEBPs and closely related to the CEBP of Homarus americanus. Quantitative real-time PCR (qPCR) analysis revealed that PvCEBP was expressed in all examined shrimp tissues, with transcript levels increased in shrimp hemocytes and gill upon WSSV challenge. Furthermore, knockdown of PvCEBP mediated by RNA interference significantly decreased the expression of WSSV genes and viral loads, while enhanced the shrimp survival rate under WSSV challenge. In silico prediction and reporter gene assays demonstrated that PvCEBP could activate the promoter activity of the viral immediate-early gene ie1. Collectively, our findings suggest that PvCEBP is annexed by WSSV to promote its propagation by enhancing the expression of viral immediate-early genes.