Atlantic salmon endothelial cells from the heart were more susceptible than fibroblasts from the bulbus arteriosus to four RNA viruses but protected from two viruses by dsRNA pretreatment

• Published in: Fish & shellfish immunology 2017-11, Vol.70, p.214-227
• Main Authors: Pham, Phuc H., Tong, Winnie W.L., Misk, Ehab, Jones, Ginny, Lumsden, John S., Bols, Niels C.
• Format: Article
• Language: English
• Subjects: Animals; Atlantic salmon; Cell Line; CSV; dsRNA; Endothelial cell line; Endothelial Cells; Female; Fibroblasts; Fish Diseases - therapy; Fish Diseases - virology; Fish Proteins - metabolism; Fish viruses; Heart Diseases - therapy; Heart Diseases - veterinary; Heart Diseases - virology; IPNV; Mx protein; Myxovirus Resistance Proteins - metabolism; Poly I:C; RNA Virus Infections - therapy; RNA Virus Infections - veterinary; RNA Virus Infections - virology; RNA Viruses - physiology; RNA, Double-Stranded - pharmacology; Salmo salar; VHSV
• ISSN: 1050-4648; 1095-9947
• DOI: 10.1016/j.fsi.2017.09.001

Heart diseases caused by viruses are major causes of Atlantic salmon aquaculture loss. Two Atlantic salmon cardiovascular cell lines, an endothelial cell line (ASHe) from the heart and a fibroblast cell line (BAASf) from the bulbus arteriosus, were evaluated for their response to four fish viruses, CSV, IPNV, VHSV IVa and VHSV IVb, and the innate immune agonist, double-stranded RNA mimic poly IC. All four viruses caused cytopathic effects in ASHe and BAASf. However, ASHe was more susceptible to all four viruses than BAASf. When comparing between the viruses, ASHe cells were found to be moderately susceptible to CSV and VHSV IVb, but highly susceptible to IPNV and VHSV IVa induced cell death. All four viruses were capable of propagating in the ASHe cell line, leading to increases in virus titre over time. In BAASf, CSV and IPNV produced more than one log increase in titre from initial infection, but VHSV IVb and IVa did not. When looking at the antiviral response of both cell lines, Mx proteins were induced in ASHe and BAASf by poly IC. All four viruses induced Mx proteins in BAASf, while only CSV and VHSV IVb induced Mx proteins in ASHe. IPNV and VHSV IVa suppressed Mx proteins expression in ASHe. Pretreatment of ASHe with poly IC to allow for Mx proteins accumulation protected the culture from subsequent infections with IPNV and VHSV IVa, resulting in delayed cell death, reduced virus titres and reduced viral proteins expression. These data suggest that endothelial cells potentially can serve as points of infections for viruses in the heart and that two of the four viruses, IPNV and VHSV IVa, have mechanisms to avoid or downregulate antiviral responses in ASHe cells. Furthermore, the high susceptibility of the ASHe cell line to IPNV and VHSV IVa can make it a useful tool for studying antiviral compounds against these viruses and for general detection of fish viruses. •Atlantic salmon heart endothelial cell line (ASHe) is very sensitive to IPNV and VHSV IVa.•IPNV and VHSV IVa, but not CSV and VHSV IVb, suppressed Mx protein expression in ASHe.•Poly IC pretreatment of ASHe protected the cells from IPNV and VHSV IVa infection.•Atlantic salmon bulbus arteriosus fibroblast cell line (BAASf) is not as sensitive to the tested fish RNA viruses as ASHe.