Establishment and characterization of a new cell line derived from half-smooth tongue sole Cynoglossus semilaevis kidney

In this study, we established a new cell line (Cynoglossus semilaevis kidney cells, CSK) from kidney of the half-smooth tongue sole (Cynoglossus semilaevis). The cells were subcultured over 1 000 days and passaged for more than 100 times. Additionally, CSK cells were optimally maintained in Dulbecco’s modified Eagle medium nutrient mixture F-12 supplemented with HEPES, antibiotics, fetal bovine serum, 2-mercaptoethanol, and basic fibroblast growth factor. The optimum growth temperature for CSK cells was 25°C, and the cells showed a fibroblast-like phenotype. Chromosome analysis revealed that CSK cells had a normal diploid karyotype with 2n=42. CSK cells were susceptible to Grouper nervous necrosis virus (NNV), and cytopathic effects were observed at 3–5 days postinfection. The NNV sensitivity of CSK cells was related to the high abundance of virions in the cytoplasm, as observed by electron microscopy. Additionally, CSK cells could be successfully transfected with a green fluorescent protein reporter plasmid, and fluorescent signals were easily observed. Finally, immunocytochemistry analysis showed that CSK cells were supporting cells. Overall, we established this new cell line, which may have potential applications in the identification of viral pathogens affecting the half-smooth tongue sole.