Dual function of a zinc finger transcription factor PvBr-C in Penaeus vannamei

The Broad-Complex (Br-C) is a pivotal transcription factor in arthropod development and metamorphosis, but its functional roles in crustaceans remain poorly understood. In this study, we identified and characterized a Br-C homolog (PvBr-C) in Penaeus vannamei through molecular cloning, phylogenetic analysis, and functional investigation. The 2343-bp cDNA encoded a 781-amino-acid protein containing conserved BTB_POZ and zinc finger domains, exhibiting high homology with the analogous sequences in decapod crustaceans. Tissue-specific expression profiling revealed predominant PvBr-C expression in the hemocytes, suggesting an immune-related role. RNA interference (RNAi) demonstrated that pvbr-c transcription was regulated by pvhpo, linking it to immunity regulation. Knockdown of pvbr-c significantly suppressed WSSV replication, as indicated by reduced expression of viral immediate-early (ie1) and late (vp28) genes. Transcriptome analysis of pvbr-c-silenced shrimp revealed differential regulation of immune effectors (e.g., AMPs, proPO system components, and hematopoietic factors) and developmental genes (e.g., ecdysone signaling components, forkhead box protein, and crustacean hyperglycemic hormone). Dual-luciferase assays confirmed that PvBr-C activated the promoters of wsv249 and wsv465, indicating its co-option by WSSV to facilitate replication. These findings establish PvBr-C as a dual-function regulator in P. vannamei, orchestrating both developmental processes via ecdysone signaling and antiviral immunity, while serving as a proviral factor that can be hijacked by WSSV. This study provides novel insights into the interplay between crustacean molting pathways and host-virus interactions, with implications for managing WSSV outbreaks in aquaculture.