Establishment and characterization of a new cell line derived from the fin of olive flounder (Paralichthys olivaceus)

The olive flounder (Paralichthys olivaceus) is an economically important marine fish species in several East Asian countries. Previously, some cell lines have been derived from the olive flounder, which have shown sensitivity to some viral infections that occur in the fish. In this study, we generated a new immortal cell line, named Korea fin Tissue from Sea flounder (KTS), from the fin tissues of olive flounder and successfully subcultured the cells approximately 250 times over 4 years. KTS cells displayed stable growth at temperatures ranging from 25 °C to 31 °C, with optimum growth at 27 °C. Thus, this cell line has a relatively higher and wider range of growth temperatures compared with other reported cell lines. Chromosome analysis showed that the cell line contains 46 chromosomes, which is fewer than those in other cell lines derived from olive flounder. Furthermore, we evaluated the susceptibility of the cell line to infectious viruses such as viral hemorrhagic septicemia virus (VHSV), infectious hematopoietic necrosis virus (IHNV), hirame rhabdovirus (HRRV), and marine birnavirus (MABV). KTS cells showed 100% cytopathic effect (CPE) at 2 weeks. Notably, KTS cells stimulated with CpG-ODN1668 or poly (I:C) showed higher expression of immune genes in the cytoplasm that were recognized by Toll-like receptor 3 (TLR3) or TLR9. These results suggested that the KTS cell line is promising for immune gene expression analysis and other genetic studies. In conclusion, we successfully generated an immortal cell line from the fin tissue of olive flounder. KTS cells have a higher growth temperature range than other reported cell lines, which could prove useful for future cytopathological, genetic, and infectious viral mechanistic studies in this species.