Multi-omics characterization and identification of small non-coding RNAs in Spiroplasma eriocheiris

Spiroplasma eriocheiris is the major pathogen in the aquaculture shrimp and crab tremor disease; its infection causes heavy losses in aquaculture. Previous investigations concentrated on how the host responds to S. eriocheiris infection, with little known on the regulation of virulence and pathogenesis by the bacteria themselves. A body of increasing evidence shows that bacterial small noncoding RNAs (sRNAs) play a crucial part in regulating bacterial virulence and pathogenesis; however, whether there are some sRNAs in S. eriocheiris and how those sRNAs regulate virulence and pathogenesis are still unclear. This study analyzed multi-omics data integration to identify the potential sRNAs and their mediated regulatory network in S. eriocheiris. First, through an integration analysis of the public genomic and transcriptomic data, 54 potential sRNAs were identified in S. eriocheiris with a 50–250 nt length distribution and the base composition mainly AT. Next, sRNA profiling of the in vitro logarithmic and decline phase of S. eriocheiris, as well as the early and onset stage of infection in Eriocheir sinensis, was performed, showing that 4 sRNAs (SR01, SR05, SR08, and S04) were both down-regulated in the logarithmic and the onset stage of infection. Subsequently, integrated with sRNAs target gene prediction and target gene expression analysis, a regulatory network composed of four sRNAs and 96 target genes was constructed. Last, an RNA pull-down experiment was performed on the SR01, which exhibited the highest abundance and the highest number of target genes, resulting in 37 highly credible target genes with multiple genes related to bacterial virulence, such as GTPases and virulence factor coding genes. Collectively, this study identified the sRNAs in S. eriocheiris and revealed their mediated regulatory network for regulating virulence and pathogenesis, thus paving a new avenue for disease prevention and control in aquaculture.