Vibrio Harveyi exosomes secrete VgrG protein and cause toxic effects to Ruditapes philippinarum
Abstract
Considering the potential role of the valine-glycine repeat (VgrG), a core component of Type VI secretion system (T6SS) proteins secreted by exosomes, in the pathogenicity of Vibrio harveyi, this study aimed to understand the mechanism of V. harveyi VgrG protein in bivalves. Ultra-centrifugation was used to extract V. harveyi exosomes, which were then fluorescently labeled to enable tracking. Subsequently, reactive oxygen species (ROS), caspase-3, superoxide dismutase (SOD), glutathione peroxidase (GPx), and malondialdehyde (MDA) were detected in the hemocytes of Ruditapes philippinarum. Protein changes were determined using 4D TOF Pro2 mass spectrometry in combination with DIA-PASEF scanning mode after exposure to recombinant VgrG protein for 24 hours. Our results showed that V. harveyi exosomes could enter host cells and exert toxic effects. VgrG interferes with the primary metabolism and energy balance of R. philippinarum by inhibiting key energy metabolism pathways and protein synthesis, as well as inducing oxidative stress and apoptosis. These findings suggest that VgrG could play a critical role in the functionality of T6SS proteins in V. harveyi and provide a novel perspective for analyzing Vibrio pathogenic mechanisms via exosomes. This paper has not been published yet
