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Diseases of Aquatic Organisms

    DAO prepress abstract   -  DOI: https://doi.org/10.3354/dao03499

    Isolation and characterisation of an ISKNV-genotype megalocytivirus from imported angelfish Pterophyllum scalare

    Yasuhiko Kawato*, Peter G. Mohr, Mark St. J. Crane, Lynette M. Williams, Matthew J. Neave, David M. Cummins, Megan Dearnley, Sandra Crameri, Clare Holmes, John Hoad, Nicholas J. G. Moody

    *Corresponding author:

    ABSTRACT: Using cultures of the SKF-9 cell line, a megalocytivirus named AFIV-16, was isolated from imported angelfish Pterophyllum scalare that had been held in quarantine at the Australian border. The cytopathic effect caused by isolate AFIV-16 presented as cell rounding and enlargement, but complete destruction of the infected cell cultures did not occur. The infected cells demonstrated immunocytochemical reactivity with monoclonal antibody M10 which is used for diagnosis of OIE-listed red sea bream iridoviral disease. By electron microscopy, the virus particles, consisting of hexagonal nucleocapsids, were observed in the cytoplasm of SKF-9 cells. The replication of AFIV-16 in cultured SKF-9 cells at 28oC incubation was significantly greater than at 22 and 25oC incubation, whereas no difference in growth characteristics was observed for red sea bream iridovirus (RSIV) isolate KagYT-96 across this temperature range. Whole genome sequencing analysis demonstrated that AFIV-16 has 99.96% similarity to infectious spleen and kidney necrosis virus (ISKNV) which is the type species in the genus Megalocytivirus. AFIV-16 was classified into ISKNV genotype Clade1 by phylogenetic analysis of the major capsid protein gene nucleotide sequence. This is the first report of whole genome sequencing of ISKNV genotype megalocytivirus isolated from ornamental fish.