Involvement of nerve cord-expressed SVWC2 in pathogen recognition and defense in Macrobrachium nipponense

The single von Willebrand factor C-domain proteins (SVWCs) are primarily found in arthropods and are involved in responding to environmental stress, nutritional availability, and pathogen infection. In this study, an SVWC family member from the Macrobrachium nipponense was identified that contains a conserved single von Willebrand factor C domain that is highly expressed in the nerve cord (designated MnSVWC2). The role of MnSVWC2 in resistance to bacteria and viruses was investigated. MnSVWC2 is upregulated in response to both bacterial challenge and viral infection. The recombinant MnSVWC2 (rMnSVWC2) exhibited binding activity to a range of pathogen-associated molecular patterns (PAMPs). Furthermore, it exhibited Ca²⁺-dependent binding and agglutination capabilities against Gram-negative, Gram-positive bacteria and yeast. The co-incubation of rMnSVWC2 with E. coli, followed by injection into prawns, resulted in an increase in the phagocytosis of E. coli by hemocytes in vivo. ELISA analysis indicated that rMnSVWC2 can bind to white spot syndrome virus. Knockdown of MnSVWC2 by RNA interference (RNAi) resulted in an increase in virus copies in prawns and a significant decrease in survival rate following viral infection. These findings provide important insights into the function of MnSVWC2 in the innate immunity of M. nipponense and the mechanisms of defense against pathogens.