Abstract
Pseudomonas plecoglossicida is a rod-shaped, gram-negative bacterium with flagella. It causes visceral white spot disease and high mortality in Larimichthys crocea during culture, resulting in serious economic loss. Analysis of transcriptome and quantitative real-time polymerase chain reaction (PCR) data showed that dksA gene expression was significantly up-regulated after 48 h of infection with Epinephelus coioides (log2FC=3.12, P<0.001). RNAi of five shRNAs significantly reduced the expression ofdksA in P. plecoglossicida, and the optimal silencing efficiency was 96.23%. Compared with wild-type strains, the symptoms of visceral white spot disease in L. crocea infected with RNAi strains were reduced, with time of death delayed by 48 h and mortality reduced by 25%. The dksA silencing led to a substantial down-regulation in cellular component-, flagellum-, and ribosome assembly-related genes in P. plecoglossicida, and the significant up-regulation of fliC may be a way in which virulence is maintained in P. plecoglossicida. The GO and KEGG results showed that RNAi strain infection in L. crocea led to the down-regulation of inflammatory factor genes in immune-related pathways, which were associated with multiple immune response processes. Results also showed that dksA was a virulence gene in P. plecoglossicida. Compared with the wild-type strains, RNAi strain infection induced a weaker immune response in L. crocea.
Highlights
Infection is an exceedingly complex process involving strong interactions between pathogen and host (Luo et al, 2020)
Effect of dksA on P. plecoglossicida pathogenicity Compared with the wild-type strain, the dksA-RNAi strain of P. plecoglossicida exhibited a significant decrease in virulence, 412 www.zoores.ac.cn as observed by the 25% increase in the survival rate of infected L. crocea and 48 h delay in first death
The spleens of L. crocea infected by the wild-type strain showed a large number of typical white nodules on the surface at 60 hpi, whereas the spleens of L. crocea infected by the dksA-RNAi strain displayed only a small number of white spots on the surface (Figure 2B)
Summary
Infection is an exceedingly complex process involving strong interactions between pathogen and host (Luo et al, 2020) The advancement of dual RNA-seq, which can simultaneously detect both pathogen and host transcriptomes, has provided a powerful and advantageous tool for studying various infection models and pathogen-host interactions (Westermann et al, 2012, 2016, 2017; Valenzuela-Miranda & Gallardo-Escarate, 2018). Dual RNAseq and dual iTRAQ have been applied to explore gene functions at the multi-omics level (Luo et al, 2019a)
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