Dual RNA-Seq Unveils the Role of the Pseudomonas plecoglossicida fliA Gene in Pathogen-Host Interaction with Larimichthys crocea

In the present study, Larimichthys crocea and Pseudomonas plecoglossicida were selected as a host-pathogen interaction model for teleosts and prokaryotic pathogens. Five shRNAs were designed and synthesized to silence the fliA gene, all of which resulted in pronounced reductions in fliA mRNA; the mutant strain with the best silencing efficiency of 92.16% was chosen for subsequent analysis. A significant decrease in motility, intracellular survival and escape was observed for the fliA-RNAi strain of P. plecoglossicida, whereby silencing of the fliA gene led to a 30% decrease in mortality and a four-day delay in the onset of infection in L. crocea. Moreover, silencing of P. plecoglossicida fliA resulted in a significant change in both the pathogen and host transcriptome in the spleens of infected L. crocea. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of pathogen transcriptome data showed that silencing fliA resulted in downregulation of 18 flagellum-related genes; KEGG analysis of host transcriptome data revealed that infection with the fliA-RNAi strain caused upregulation of 47 and downregulation of 106 immune-related genes. These pathogen-host interactions might facilitate clearance of P. plecoglossicida by L. crocea, with a significant decrease in fliA-RNAi P. plecoglossicida strain virulence in L. crocea.