Transcriptome analysis of medaka spermatogonial stem cell line (SG3) infected with ranaviruses in vitro

The medaka spermatogonial stem cell line (SG3) is a well-established cell line that can be induced to differentiate into sperm in vitro. Ranavirus, a genus of viruses widely distributed among fish, amphibians, and reptiles, poses a significant threat to these organisms. This study aimed to investigate the morphological changes and transcriptomic responses in SG3 following infection with three ranavirus strains: Andrias davidianus ranavirus (ADRV), Rana grylio virus (RGV), and Siniperca chuatsi ranavirus (SCRaV). Microscopic observations confirmed that SG3 cells were susceptible to all three ranaviruses, resulting in cellular swelling and membrane rupture, with infection confirmed through Real-time PCR. Transcriptomic profiling identified conserved responses: downregulation of early growth response protein (Egr1) and upregulation of myelocytomatosis oncogene (MYC). Ranavirus infection elevated alternative splicing events, with skipped exon events dominated and the maximal divergence observed at the 12 h post-infection. Key cellular metabolic pathways including glycolysis were disrupted, marked by coordinated upregulation of glycolytic enzymes and suppression of gluconeogenic enzymes. These results elucidate conserved molecular strategies underlying ranavirus-host interactions and metabolic mechanisms.