Identification, functional analysis of chitin-binding proteins and the association of its single nucleotide polymorphisms with Vibrio parahaemolyticus resistance in Penaeus vannamei

Chitin-binding proteins (CBPs) play pivotal roles in numerous biological processes in arthropods, including growth, molting, reproduction, and immune defense. However, their function in the antibacterial immune defense of crustaceans remains relatively underexplored. In this study, twenty CBPs were identified and characterized in Penaeus vannamei. Expression profiling highlighted that the majority of CBPs were highly expressed in the intestine and hepatopancreas and responded to challenge by Vibrio parahaemolyticus. To explore the role of these CBPs in innate immunity, six CBPs (PvPrg4, PvKrtap16, PvPT-1a, PvPT-1b, PvExtensin and PvCP-AM1159) were selected for RNAi experiments. Silencing of only PvPrg4 and PvKrtap16 significantly decreased the cumulative mortality of V. parahaemolyticus-infected shrimp. Further studies demonstrated that inhibition of PvPrg4 and PvKrtap16 resulted in a marked upregulation of genes associated with the NF-κB and JAK-STAT signaling pathways, as well as antimicrobial peptides (AMPs), in both the intestine and hepatopancreas. These results collectively suggested that PvPrg4 and PvKrtap16 potentially promote V. parahaemolyticus invasion by negatively regulating the JAK-STAT and NF-κB pathways, thereby inhibiting the expression of AMPs. In addition, SNP analysis identified three SNPs in the exons of PvPrg4 that were significantly associated with tolerance to V. parahaemolyticus. Taken together, these findings are expected to assist in the molecular marker-assisted breeding of P. vannamei associated with anti-V. parahaemolyticus traits, as well as expand our understanding of CBP functions within the immune regulatory system of crustaceans.