Development of two cell lines from yellowfin seabream Acanthopagrus latus fin and brain suitable for propagating SDDV but not for ISKNV, MRV and GIV

Scale drop disease virus (SDDV), a very distinct member of genus Megalocytivirus in family Iridoviridae, was recently confirmed as the most alarming causative agent associated with yellowfin seabream Acanthopagrus latus ascites diseases in South China. To better understand how host-pathogen interacting and developing cell-culture based vaccine, establishment of highly susceptible cell line generating from the natural host fish for SDDV infection will be a top priority. Here, two novel cell lines from yellowfin seabream fin and brain were established and characterized, and designated as YFSBF and YFSBB, respectively. Morphologically, both cell lines pre-dominantly consisted of fibroblast-like cells and grew well in Dulbecco's modified Eagle medium supplemented with 10% fetal bovine serum. Karyotype analysis revealed that chromosome numbers of YFSBF and YFSBB were wildly distributed without obvious featured chromosomic modes. Viral susceptibility tests showed that SDDV could propagate well in both YFSBF and YFSBB, and YFSBF showed more susceptible to SDDV than YFSBB did, being confirmed by cytopathic effect observation, absolute real-time quantitative PCR determination, immu-nofluorescence assay, Western blot analysis and transmission electron microscopy examination. Viral suscepti-bility tests also confirmed that SDDV could effectively propagate in MFF-1 cell, a highly susceptible host cell line for infectious spleen and kidney necrosis virus (ISKNV), whereas either YFSBF or YFSBB was refractory to ISKNV infection. Moreover, neither YFSBF nor YFSBB could support the effective propagations of mandarin ranavirus (MRV) and grouper ranavirus (GIV-R). Collectedly, this study provides some important information for better understanding the differential infection profile among SDDV, ISKNV and other fish iridovirus.

Automated summary

In this study, two novel cell lines derived from yellowfin seabream were established and characterized, providing important information for understanding the infection characteristics of Scale drop disease virus (SDDV).