Genome-wide identification of the collectin family in silver pomfret (Pampus argenteus) and innate immune functions of a novel truncated member PaCL-11b against Vibrio parahaemolyticus.

The Collectin family, an important member of the C-type lectin superfamily, participates in innate immune defense through Ca2+-dependent recognition of glycan ligands on pathogen surfaces. In this study, five Collectin family members were identified in the silver pomfret (Pampus argenteus) genome, and their gene structures, conserved motifs, and chromosomal localizations were systematically characterized. Notably, a novel member, collectin-11b (PaCL-11b) was found to encode a truncated isoform containing only the neck region and the carbohydrate recognition domain (CRD). It exhibited the highest expression level in the liver of healthy silver pomfret and was significantly downregulated in the liver, kidney, and gills following Vibrio parahaemolyticus challenge. Functional characterization of the recombinant protein rPaCL-11b demonstrated Ca2+-dependent binding, agglutination, direct antimicrobial, and antibiofilm activities against both Gram-negative (V. parahaemolyticus and Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria, with the most potent inhibitory effects observed against V. parahaemolyticus. This study presents a systematic identification of the Collectin family in silver pomfret and reveals the multifunctional immune roles of PaCL-11b in defense against V. parahaemolyticus infection, providing a theoretical basis for the prevention and control of bacterial diseases in silver pomfret aquaculture.