Establishment and antiviral immune response characterization of fin cell lines from black carp (Mylopharyngodon piceus) and gynogenetic black carp.

Grass carp reovirus (GCRV) and spring viremia of carp virus (SVCV) cause high mortality in black carp. We have previously bred a gynogenetic black carp strain with enhanced antiviral resistance. To investigate the underlying mechanisms, we established and characterized one fin cell line (bcF) from black carp (Mylopharyngodon piceus) and two fin cell lines (gbc-1F, gbc-2F) from gynogenetic black carp. All three cell lines exhibited a uniform fibroblast-like morphology. The homology among these three cell lines was determined by 18S rDNA sequencing, and most cells of the three lines maintained a diploid karyotype (2n = 48) at passage 50, with consistent relative DNA content confirmed by flow cytometry. At passage 40, both gbc-1F and gbc-2F cells showed a faster growth rate than bcF cells. All three cell lines were suitable for immunological studies: overexpression of molecules (RIG-I, MDA5, MAVS, TBK1, IRF3, IRF7) in the RLR signaling pathway in these cells significantly upregulated the transcriptional activity of IFNα promoter. Antiviral tests revealed that gbc-1F displayed the strongest resistance to grass carp reovirus (GCRV), characterized by weak viral entry and high expression of IFNα and interferon-stimulated genes (ISGs) at the early infection stage; gbc-2F showed the strongest resistance to spring viremia of carp virus (SVCV), with weak viral entry and high early-stage ISGs expression. Proteomic analysis showed that a large number of differentially expressed proteins (DEPs) are enriched in terms related to the extracellular and cell membrane. These cell lines provide a key in vitro platform for studying the antiviral mechanisms and disease resistance advantages of gynogenetic black carp.