Identification of two novel C-type lectins involved in immune defense against white spot syndrome virus and Vibrio parahaemolyticus from Marsupenaeus japonicus

C-type lectins (CTLs) are vital molecules in crustacean innate immunity with the capacity to recognize and eliminate invaders, such as viruses and bacteria. Here, two novel CTLs were identified from the kuruma shrimp Marsupenaeus japonicas, and their molecular characteristics and immune function were investigated. Sequence analysis revealed that the two CTLs possessed the typical CTL structure and function features. Tissue distribution analysis showed that the two CTLs were most abundantly expressed in the hepatopancreas and weakly expressed in other examined tissues. The transcription of the two CTLs significantly increased in the hepatopancreas of shrimp challenged with both white spot syndrome virus (WSSV) and Vibrio parahaemolyticus, and MjCTL4 was found to be more sensitive to the two pathogens than MjCTL3, being induced at relatively faster and higher increments. GST pull-down assays showed that the two CTLs could directly interact with several WSSV envelope proteins (VP19, VP24, VP26 and VP28). Moreover, the two CTLs displayed obvious binding and antibacterial ability to V. parahaemolyticus, and MjCTL3 exhibited stronger anti-V. parahaemolyticus activity than MjCTL4. These results suggest that the two novel CTLs might function as pattern recognition receptors (PRRs) and antibacterial molecules in M. japonicas innate immunity, and the two CTLs may be alternative agents for the prevention and treatment of diseases caused by WSSV and V. parahaemolyticus.