Mechanistic insight into the roles of Pseudomonas plecoglossicida clpV gene in host-pathogen interactions with Larimichthys crocea by dual RNA-seq.

Large yellow croaker (Larimichthys crocea) is an economical important farmed fish in China. "Visceral White Spot Disease" caused by Pseudomonas plecoglossicida is a disease with a high mortality rate in cage-cultured L. crocea in recent years and resulted in heavy economy lossess. The dual RNA-seq results of previous study showed that the expression of clpV gene in P. plecoglossicida was significantly up-regulated during infection. RNAi significantly reduced the expression of clpV in P. plecoglossicida with maximum silencing efficiency of 96.1%. Compared with the wild type strain, infection of clpV-RNAi strain resulted in a delayed onset time and a 25% reduction in mortality of L. crocea, as well as lessening the symptoms of the spleen. The results of dual RNA-seq of L. crocea infected by clpV-RNAi strain of P. plecoglossicida changed considerably, compared with the counterpart infected with the wild strain. The KEGG enrichment analysis showed that Cytokine-cytokine receptor interaction, Toll-like receptor signaling pathway, C-type lectin receptor signaling pathway and MAPK signaling pathway of L. crocea were most affected by the silence of clpV in P. plecoglossicida. RNAi of clpV resulted in the downregulation of genes in flagella assembly pathway and a weaker immune response of host.