DAO 119:253-258 (2016)  -  DOI: https://doi.org/10.3354/dao02985

NOTE
Megalocytivirus infection in cultured Nile tilapia Oreochromis niloticus

Kuttichantran Subramaniam1,*, Michael Gotesman1, Charlie E. Smith2, Natalie K. Steckler1, Karen L. Kelley3, Joseph M. Groff4, Thomas B. Waltzek

1Department of Infectious Diseases and Pathology, College of Veterinary Medicine, University of Florida, Gainesville, Florida 32611, USA
2715 SE 5th St., College Place, Washington 99324, USA
3Electron Microscopy Core, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, Florida 32611, USA
4School of Veterinary Medicine, University of California Davis, Davis, California 95616, USA
*Corresponding author:

ABSTRACT: Megalocytiviruses, such as infectious spleen and kidney necrosis virus (ISKNV), induce lethal systemic diseases in both ornamental and food fish species. In this study, we investigated an epizootic affecting Nile tilapia Oreochromis niloticus cultured in the US Midwest. Diseased fish displayed lethargy, gill pallor, and distension of the coelomic cavity due to ascites. Histopathological examination revealed a severe systemic abundance of intravascular megalocytes that were especially prominent in the gills, kidney, spleen, liver, and intestinal submucosa. Transmission electron microscopic examination revealed abundant intracytoplasmic polygonal virions consistent with iridovirus infection. Comparison of the full-length major capsid protein nucleotide sequences from a recent outbreak with a remarkably similar case that occurred at the same facility many years earlier revealed that both epizootics were caused by ISKNV. A comparison of this case with previous reports suggests that ISKNV may represent a greater threat to tilapia aquaculture than previously realized.


KEY WORDS: Iridoviridae · Megalocytivirus · Infectious spleen and kidney necrosis virus · Aquaculture · Ornamental fish


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Cite this article as: Subramaniam K, Gotesman M, Smith CE, Steckler NK, Kelley KL, Groff JM, Waltzek TB (2016) Megalocytivirus infection in cultured Nile tilapia Oreochromis niloticus. Dis Aquat Org 119:253-258. https://doi.org/10.3354/dao02985

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