@article{mbs:/content/journal/jgv/10.1099/vir.0.19087-0, author = "Joseph, Tomy and Kibenge, Molly T. and Kibenge, Frederick S. B.", title = "Antibody-mediated growth of infectious salmon anaemia virus in macrophage-like fish cell lines", journal= "Journal of General Virology", year = "2003", volume = "84", number = "7", pages = "1701-1710", doi = "https://doi.org/10.1099/vir.0.19087-0", url = "https://www.microbiologyresearch.org/content/journal/jgv/10.1099/vir.0.19087-0", publisher = "Microbiology Society", issn = "1465-2099", type = "Journal Article", 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.", }