Establishment and characterization of fin cell lines from koi carp ( Cyprinus carpio koi )

Koi herpesvirus (KHV) tentatively categorized as a member of the Alloherpesviridae under the species name Cyprinid herpesvirus 3 (CyHV-3). Since 1998, lethal infections of KHV have been spreading, threatening the worldwide production of common carp and koi (both Cyprinus carpio), the first case in Taiwan has been identified in December 2002. Until now, KHV research has impeded by the lack of suitable cell line in Taiwan. In this study, two cell line were established and characterized from koi Cyprinus carpio koi fin tissue. These cell lines have been designated as Koi Fin cell 1 (KF1) and Koi Fin cell 2 (KF2), respectively. Both cell lines were epithelial-like cells. These cells multiplied well in Leibovitz’s L-15 medium, supplemented with 5 to 10% foetal bovine serum, at temperatures between 25 to 31 ℃, and have been subcultured more than 40 passages. Chromosome morphologies of KF1 and KF2 were homogeneous, and the chromosome number of KF1 and KF2 distributed major in 48. These cell lines upon transfection, using pEGFP-N1, produced significant fluorescent signals indicating their potential utility for exogenous studies. Furthermore, UV-irradiated KF2 underwent apoptosis after incubation 4 hr indicating this cell line have potential utility for apoptosis researches. KF2 was susceptible to KHV, and the infection titer can reach 101.5 TCID50/ml, and the sequence alignment is 100% similarity with KHV-USA Thymidine kinase gene. All these results suggest that the established
Koi Fin (KF) cell line is suitable for the cell biology study of Koi herpesvirus.