Establishment of a Leopard Coral Grouper (Plectropomus leopardus) Fin Cell Line (PLF): A Robust Tool for Investigating Viral Pathogenesis and Host Immunity

Leopard coral grouper (Plectropomus leopardus) is a commercially important marine fish species. It is important to study how to prevent it from infecting with various viruses. In this study, we established and characterized a new cell line derived from the fin tissue of leopard coral grouper (PLF). The PLF cells were cultured for more than 55 passages. Cytochrome B gene sequencing confirmed the origin of the PLF cells is P. leopardus. Immunostaining against cytokeratin indicated that the PLF cells predominantly consist of epithelial cells. The chromosome number of PLF was 48. The cells grew well in Dulbecco’s modified Eagle’s medium (DMEM) supplemented with 10%–20% fetal bovine serum (FBS) at temperature between 20–28 °C, with the highest growth rate at 28 °C. Transfection with pEGFP-N3 plasmid showed the transfection efficiency was about 35%. Virus susceptibility tests revealed that PLF cells are susceptible to red-spotted grouper nervous necrosis virus (NNV) and viral hemorrhagic septicemia virus (VHSV), and viral proliferation was confirmed by qRT-PCR and western blot. The altered expressions of immune-related genes TBK1, IRF3, and Mx after NNV and VHSV infections suggested that PLF cells can mount an immune response to fish viruses. Thus the PLF cells can be employed for studying virus-host interactions and developing antiviral strategies.