Effect of WSSV infection on immunity, intestinal microbial composition and its derived metabolites synthesis in Procambarus clarkii

Intestinal microbes play a pivotal role in the pathogenesis of disease, with derived metabolites acting as key mediators. The WSSV results in considerable economic losses to the crayfish aquaculture industry. We constructed an artificial infection model of WSSV in crayfish and conducted a comprehensive investigation into the alterations in non-specific immunity, intestinal microbial structure, and functional metabolites of crayfish following WSSV infection by integrating 16S rDNA and targeted metabolomics techniques. WSSV infection induced oxidative stress and hepatopancreatic injury. RT-PCR results indicated that WSSV infection resulted in a significant upregulation of the transcript levels of genes related to the proPO system (proPO and Crustin), the inflammatory response (Relish, Cox-1 and Cox-2) and autophagy (LC3 and Atg2) in crayfish hemocytes. Transcript levels of genes associated with apoptosis (Caspase3), lectins (L-Lectin) and phagocytosis (Rab5) were significantly reduced. The abundance of the Proteobacteria and the Aeromonas genus markedly increased, while the Anaerorhabdus furcosa and Akkermansia was significantly diminished in infected crayfish. BugBase prediction indicated the pathogenic potential and oxidative stress tolerance of the intestinal microbiota increased following infection. Targeted metabolomic analyses revealed a significant decrease in acetate and a significant increase in GCDCA in the chyme of the infected crayfish. The results suggest that intestinal microorganisms and their specific functional metabolites, acetate and GCDCA, are involved in WSSV infection and immune mobilisation of crayfish. The present study offers new insights and avenues for understanding the pathogenic mechanisms of WSSV and precise targets for the development of novel anti-WSSV modulators.