MicroRNA profiling yields immune response and metabolic changes in juvenile largemouth bass (Micropterus salmoides) infected with LMBV

The largemouth bass virus (LMBV) exhibits high pathogenicity in both adult and juvenile largemouth bass, causing substantial economic losses within the aquaculture industry. MicroRNAs (miRNAs) are crucial in controlling viral infections and the host's immune responses, making them significantly valuable in the treatment and diagnosis of diseases. Nevertheless, research on miRNA expression profiles associated with LMBV infection in largemouth bass is currently insufficient. This research attempts to investigate the roles and molecular mechanisms of miRNAs in the potential immune response and metabolic alterations triggered by LMBV infection in largemouth bass using miRNA sequencing. Following quality screening, the infection group and control group yielded a combined total of 142.73 million clean reads, with lengths predominantly at 22 ​nt. 1718 known miRNAs were identified, including 238 differentially expressed miRNAs (DEMs). In addition, 400 novel miRNAs were predicted, 36 of which were DEMs. To gain further insight into the immune and metabolic related biological functions of DEMs, target gene prediction was conducted. KEGG pathway analysis revealed that LMBV impacted pathways such as Endocytosis, Purine metabolism, Phosphatidylinositol, Fatty acid Biosynthesis, and Phagosome signaling systems, highlighting the vital role of miRNAs in immune responses and metabolic alterations. Furthermore, the miRNA-mRNA interaction network revealed crucial miRNAs and their corresponding target genes involved in conferring resistance against viral infections by utilizing metabolic and immune related pathways as the foundation. Ten DEMs were selected at random for real-time quantitative PCR (qRT-PCR), and results exhibited expression patterns that were consistent with sequencing data. These findings validate the immune and metabolic regulatory function of miRNAs against LMBV in largemouth bass, offering valuable perspectives for the prevention and management of illnesses linked to iridoviruses. • MicroRNA transcriptome analysis was initially performed on largemouth bass infected with LMBV. • 238 known and 36 novel DEMs were identified in response to LMBV infection. • Key pathways including Endocytosis, Purine metabolism, Phosphatidylinositol, FAS, and Phagosomes were enriched. • MiRNA-mRNA network revealed key antiviral immune and metabolic regulated responses.