Characterization of a novel brain cell line from Jian carp (Cyprinus carpio var. Jian)

Jian carp (Cyprinus carpio var. Jian) is an economically important cultured fish in China. Currently, it is facing threats from infectious diseases including koi herpesvirus (KHV). Here, we established a new cell line, designated CCB-J, derived from the brain tissue of the Jian carp. CCB-J cells grew well in Leibovitz's L-15 medium containing 20% fetal bovine serum at 25 °C and have been subcultured for more than 60 passages. At the 30th passage, analysis showed that the number of chromosomes was 100, which is identical to that of other carp variants. Sequencing of the 18S ribosomal DNA confirmed that CCB-J originated from Jian carp. After transfection with the pEGFP-N1 plasmid, green fluorescence was observed in CCB-J. The replication of KHV in CCB-J cells was confirmed by RT-PCR and transmission electron microscopy. The viral titers of KHV in CCB-J cells and CCB cells, which have been widely used in the study of KHV, reached 10^3.9 and 10^1.8 median tissue culture infectious dose (TCID₅₀/mL), respectively, within 14 days. The result of TaqMan PCR revealed that CCB-J cells were more sensitive to KHV than CCB cells. Meanwhile, a cytopathic effect (CPE) was also observed in the CCB-J cells in a shorter time post-infection compared with CCB cells. In summary, the CCB-J cell line will be a useful tool in the study of viral pathogenesis and vaccine research.