Complete genome sequences of infectious spleen and kidney necrosis virus isolated from farmed albino rainbow sharks Epalzeorhynchos frenatum in the United States

• Published in: Virus genes Vol. 57; no. 5; pp. 448 - 452
• Main Authors: Koda, Samantha A., Subramaniam, Kuttichantran, Pouder, Deborah B., Yanong, Roy P., Frasca, Salvatore, Popov, Vsevolod L., Waltzek, Thomas B.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.10.2021; Springer Nature B.V
• Subjects: Albinism; albino; Aquaculture; Biomedical and Life Sciences; Biomedicine; DNA; DNA sequencing; Epalzeorhynchos frenatum; Farms; Genomes; genotype; Genotypes; histopathology; Inclusion bodies; Infectious spleen and kidney necrosis virus; Kidneys; Medical Microbiology; Necrosis; Next-generation sequencing; Plant Sciences; Short Report; Spleen; transmission electron microscopy; Virology; Viruses; Whole genome sequencing; United States > US; Complete genome sequence; Megalocytivirus; Rainbow shark; Iridovirus; Infectious spleen and kidney necrosis virus
• ISSN: 0920-8569; 1572-994X; 1572-994X
• DOI: 10.1007/s11262-021-01857-6

The genus Megalocytivirus includes viruses known to cause significant disease in aquacultured fish stocks. Herein, we report the complete genome sequences of two megalocytiviruses (MCVs) isolated from diseased albino rainbow sharks Epalzeorhynchos frenatum reared on farms in the United States in 2018 and 2019. Histopathological examination revealed typical megalocytivirus microscopic lesions (i.e., basophilic cytoplasmic inclusions) that were most commonly observed in the spleen and kidney. Transmission electron microscopic examination of spleen and kidney tissues from specimens of the 2018 case revealed hexagonally shaped virus particles with a mean diameter of 153 ± 6 nm ( n  = 20) from opposite vertices and 131 ± 5 nm ( n  = 20) from opposite faces. Two MCV-specific conventional PCR assays confirmed the presence of MCV DNA in the collected samples. Full genome sequencing of both 2018 and 2019 Epalzeorhynchos frenatus iridoviruses (EFIV) was accomplished using a next-generation sequencing approach. Phylogenomic analyses revealed that both EFIV isolates belong to the infectious spleen and kidney necrosis virus (ISKNV) genotype within the genus Megalocytivirus . This study is the first report of ISKNV in albino rainbow sharks.