Transcriptome analysis of the spermatogonial stem cell line of Opsariichthys bidens after infection with three strains of ranaviruses

The long-term-cultured Opsariichthys bidens spermatogonial stem cell line (ObSSC) was established in our previous study, which could be induced to differentiate into sperm in vitro. The genus Ranavirus is a large double-stranded DNA virus with a high degree of pathogenicity, which can be widely transmitted in fish, amphibians and reptiles. It is highly representative and possesses significant research value. The present study aimed to investigate the morphological changes and transcriptome analyses of ObSSC following infection by the three strains of ranaviruses (Andrias davidianus ranavirus, ADRV; Rana grylio virus, RGV; Siniperca chuatsi ranavirus, SCRaV). Microscopic observation and polymerase chain reaction (PCR) detection techniques were employed to ascertain that ObSSC could be invaded by ranaviruses, resulting in the formation of cell shed plaques and other lesions. Transcriptome analysis revealed the high degree of similarity among different infections of ranaviruses. The genes Egr1 (early growth response protein 1) and Dusp2 (dual specificity protein phosphatase 2) were downregulated after infection. The downregulation of PI3K-AKT and MAPK signaling pathways was observed in all infected groups, which may be related to the interference of viral infection on cell growth, biological process and apoptosis. At the same time, specific responses of the host cells were observed by infections of different types of ranaviruses. The expression of phagosome was upregulated in the ADRV-infected group, whereas the Junctional Adhesion Molecule (JAM2) and the leukocyte transendothelial migration pathway was upregulated in the RGV-infected group, and the Fc gamma R-mediated phagocytosis was upregulated in the SCRaV-infected group. These findings provided important clues for further understanding of the mechanism of ranaviruses infection and host cell response.