A novel perlucin with immune regulatory functions protects Litopenaeus vannamei against Vibrio parahaemolyticus infection.

C-type lectins (CTLs), a class of carbohydrate-recognizing glycoproteins, play a vital role in immune response against bacterial infection. Vibrio parahaemolyticus is a major bacterial pathogen in shrimp, causing huge economic losses to shrimp farming. The role of the CTL family in anti-V. parahaemolyticus immunity requires further exploration. In this study, a novel CTL named Perlucin with immune regulatory functions was characterized from Litopenaeus vannamei. Perlucin was highly expressed in the muscle and hepatopancreas of healthy L. vannamei. The mRNA levels of Perlucin were significantly upregulated after LPS stimulation, and V. parahaemolyticus, Staphylococcus aureus and Aspergillus niger infections. Silencing of Perlucin by injection of specific dsRNA decreased the survival rate of V. parahaemolyticus-infected shrimp and increased the bacterial load of V. parahaemolyticus in tissues, while injection of recombinant Perlucin protein had the opposite effect. Moreover, silencing of Perlucin significantly affected the expression of multiple immune-related genes, including immune signaling components and downstream effector genes, suggesting that Perlucin is involved in immune regulation. This suggests that perlucin plays a crucial role in regulating humoral immune response against V. parahaemolyticus infection in shrimp.