Dual RNA-Seq reveals the role of a transcriptional regulator gene in pathogen-host interactions between Pseudomonas plecoglossicida and Epinephelus coioides.

Pseudomonas plecoglossicida is a highly pathogenic bacterium for maricultured fish and causes serious losses. A transcriptional regulator gene RK21_RS10315 was found up-regulated during the whole infection process, which was confirmed by qRT-PCR. Five shRNA were designed to silence RK21_RS10315 gene, and the gene expression was reduced up to 96.1%. Compared with the counterpart infected with wild type strain, the infection of RK21_RS10315-RNAi strain resulted in the death time delay, and 90% reduction in mortality of Epinephelus coioides, as well as the alleviation in the symptoms of E. coioides spleen. Moreover, compared with the fish infected with wild type strain, the infection of RK21_RS10315-RNAi strain of P. plecoglossicida resulted in a significant change both in transcriptome of spleen of infected E. coioides and P. plecoglossicida. The KEGG analysis showed that genes of 16 immune pathways in E. coioides were affected by the silence of RK21_RS10315 of P. plecoglossicida. Among them, intestinal immune network for IgA production pathway and leukocyte transendothelial migration pathway were more prominent than other pathways. 19 euk-DEMs in these immune pathways had varying degrees of correlation with 19 pro-DEMs, and the expression of ipxA, grpE, yhbJ, truD and suhB from 19 pro-DEMs were predicted more related to RK21_RS10315 in P. plecoglossicida.