LAUSR

Abstract Pseudomonas plecoglossicida is an important pathogen of maricultured fish in China and caused great loss. In this study, the mRNA level of pvdE gene of wild-type strain of P. plecoglossicida (NZBD9) was significantly decreased by 5 shRNAs and the mutant with the best silencing efficiency (89.4%) were chosen for subsequent research. Injection of pvdE-RNAi strain at a dose of 105 cfu/fish did not cause death in orange-spotted grouper and there were only a few less obvious white spots on the surface of infected spleens. Although the injection of pvdE-RNAi strain of P. plecoglossicida induced antibody production of orange-spotted grouper, the premonition of mutant infected grouper did not produce good immune protection against subsequent wild strain infection. The results of RNA-seq revealed the significant differences between the transcriptome of orange-spotted grouper infected by pvdE-RNAi strain of P. plecoglossicida and the counterpart fish infected by stain NZBD9 as well as those of orange-spotted grouper injected by PBS. Th1 and Th2 cell differentiation, Intestinal immune network for IgA production, Th17 cell differentiation, Natural killer cell mediated cytotoxicity, Chemokine signaling pathway, Hematopoietic cell lineage and T cell receptor signaling pathway were the seven immune pathways most affected by silence of pvdE gene.