title: Antibody-mediated growth of infectious salmon anaemia virus in macrophage-like fish cell lines.
abstract: Infectious salmon anaemia virus (ISAV), a pathogen in marine aquaculture, belongs to the genus Isavirus, family Orthomyxoviridae. There is limited information on how ISAV interacts with host defences. To study ISAV-antibody interactions, virus neutralization (VN) assays were performed in the cell lines CHSE-214, SHK-1 and TO using three strains of ISAV and rabbit or fish anti-ISAV sera. Homologous VN titres of >1 : 1280 in CHSE-214 cells corresponded to titres of only 1 : 80 in the macrophage-like fish cell lines SHK-1 and TO, despite using 1000 and 2000 times less virus, respectively. However, rabbit antiserum to infectious pancreatic necrosis virus (IPNV) had a VN titre of 1 : 10,260 against IPNV in both CHSE-214 and TO cells. Poor ISAV neutralization in TO cells was attributed to Fc receptors mediating virus infectivity, because (1) neutralization by rabbit antiserum to ISAV was increased 48-fold in the presence of staphylococcal Protein A and (2) when using FITC-labelled virus and spectrofluorometry, a significant increase (P=0.018) in the intensity of fluorescence of intracellular virus was observed in assays of virus-antiserum mixtures in the absence of Protein A as compared to those in the presence of Protein A. Neutralization of ISAV with fish antisera was observed only in CHSE-214 cells, as Protein A could not restore neutralization in TO cells. These findings demonstrate for the first time antibody-mediated infection of macrophage-like fish cell lines by a fish virus, ISAV, and, as ISAV in Atlantic salmon targets leukocytic and endothelial cells, this may have implications for ISA pathogenesis and vaccination.
authors.affiliation: Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PEI, Canada C1A 4P3.
authors.forename: Tomy
authors.initials: T
authors.lastname: Joseph
authors.affiliation: Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PEI, Canada C1A 4P3.
authors.forename: Molly T
authors.initials: MT
authors.lastname: Kibenge
authors.affiliation: Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PEI, Canada C1A 4P3.
authors.forename: Frederick S B
authors.initials: FSB
authors.lastname: Kibenge
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology*; D019067:Antibody-Dependent Enhancement; D002460:Cell Line; D016650:Fluorescein-5-isothiocyanate / Q000378:metabolism; D008264:Macrophages / Q000821:virology*; D009500:Neutralization Tests; D017686:Oncorhynchus mykiss / Q000821:virology*; D009975:Orthomyxoviridae / Q000276:immunology / Q000472:pathogenicity*; D011817:Rabbits; D011961:Receptors, Fc / Q000378:metabolism; D020317:Salmo salar / Q000821:virology*; D013205:Staphylococcal Protein A / Q000276:immunology; D014779:Virus Replication
chemical_list: D000914:Antibodies, Viral; D011961:Receptors, Fc; D013205:Staphylococcal Protein A; D016650:Fluorescein-5-isothiocyanate