Grunt Fin (GF)

Establishment and Characterization of a Dwarf Gourami Fin (DGF) Cell Line for Iridovirus Propagation

Fish-derived primary cell lines are invaluable for virological studies due to their rapid growth and high viral susceptibility. Jeong et al. established a novel cell line, dwarf gourami fin (DGF), derived from the caudal fin of Trichogaster lalius, and characterized its optimal growth conditions, karyotype, transfection efficiency, and viral susceptibility.

Viral susceptibility assays revealed distinct cytopathic effects (CPE) across cell lines. Following red sea bream iridovirus (RSIV) inoculation, typical megalocytivirus CPE (cell rounding, shrinking, detachment) was observed in DGF, RBF, and GF cells within 7 days, whereas PMF cells exhibited only rounding (Fig. 1A). Infectious spleen and kidney necrosis virus (ISKNV) induced weak CPE in GF cells, but none in PMF cells. Notably, DGF and RBF cells exhibited extensive cell enlargement and rounding by 4 days post-infection (dpi) with ISKNV, progressing to monolayer disruption in RBF cells, though DGF cells retained monolayer integrity through 7 dpi (Fig. 1B).

Quantification of supernatants at 7 dpi revealed distinct viral replication profiles (Fig. 1C). For RSIV, PMF cells yielded the highest titers (5.98 × 10¹⁰ genome copies/mL; 10^9.44 TCID₅₀/mL), approximately fivefold higher than DGF cells, though infectious titers were not statistically different. Conversely, DGF cells supported the highest ISKNV replication (5.22 × 10⁹ genome copies/mL; 10⁸·⁴⁸ TCID₅₀/mL), which was approximately 100-fold greater than in RBF cells and significantly higher than in GF cells (3.27 × 10⁵ genome copies/mL). These results demonstrate that the DGF cell line is a highly susceptible and efficient model for ISKNV propagation.