Mechanisms Underlying the Virulence Regulation of ND-01 and with a Transcriptomic Analysis.

is a common opportunistic pathogen of fish, shrimp, and shellfish, and many diseases it causes can result in severe economic losses in the aquaculture industry. Causing host disease was confirmed by several virulence factors of To date, there have been no reports on the effect of the gene on its virulence regulation of . The virulence mechanism of target genes regulating is worthy of further study. Previous studies found that (30 mg/mL) inhibited the growth of ND-01 (OD = 0.5) for 4 h, while the expressions of and were significantly affected by stress. So, we speculated that and might be the virulence genes of , which were stably silenced by RNAi to construct the silencing strains -RNAi and -RNAi, respectively. After the expression of or gene was inhibited, the adhesion capacity and biofilm formation of were significantly down-regulated. The chemotaxis and biofilm formation ability of -RNAi was reduced by 33.33% and 68.13% compared with the wild-type strain, respectively. Sequence alignment and homology analysis showed that was highly conserved, which suggested that played a vital role in the secretion system of . The -RNAi with the highest silencing efficiency was selected for transcriptome sequencing. The Differentially Expressed Genes (DEGs) and GO terms were mapped to the reference genome of , including 1055 up-regulated genes and 1134 down-regulated genes. The functions of the DEGs were analyzed by GO and categorized into different enriched functional groups, such as ribosome synthesis, organelles, biosynthesis, pathogenesis, and secretion. These DEGs were then mapped to the reference KEGG pathways of and enriched in commonalities in the metabolic, ribosomal, and bacterial secretion pathways. Therefore, and could regulate the bacterial virulence of by affecting its adhesion, biofilm formation ability, and motility. Understanding the relationship between the expressions of and with bacterial virulence could provide new perspectives to prevent bacterial diseases.