The outer membrane vesicles of Vibrio parahaemolyticus elicit innate immune responses in mud crab (Scylla paramamosain)

Outer membrane vesicles (OMVs) are extracellular nanostructures secreted by bacteria, which carry various virulence factors and play a pivotal role in the pathogenesis of bacterial infections. In this study, outer membrane vesicles derived from Vibrio parahaemolyticus (Vp-OMVs) were isolated to examine their effects on innate immunity in mud crabs (Scylla paramamosain). Characterization of the Vp-OMVs confirmed the presence of vesicles exhibiting typical OMV morphology and size. Vp-OMVs were internalized by host cells through clathrin-mediated endocytosis, leading to cytotoxicity, increased mortality, tissue vacuolation, and reduced cell viability. Furthermore, Vp-OMVs were found to contain lipopolysaccharide (LPS), which activates the Toll2 receptor, thereby initiating the Toll2 signaling pathway and promoting the expression of antimicrobial peptides. Additionally, internalized Vp-OMVs triggered inflammasome activation and mitochondrial dysfunction, resulting in inflammation and apoptosis. These findings highlight the critical role of Vp-OMVs in the pathogenesis of V. parahaemolyticus infections in mud crabs and offer valuable insights into potential therapeutic strategies for managing these infections.