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Diseases of Aquatic Organisms

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DAO 41:237-239 (2000)  -  doi:10.3354/dao041237

Hepatic lesions in a redstriped rockfish (Sebastes proriger) suggestive of a herpesvirus infection

M. L. Kent1,*, M. S. Myers2

1Center for Salmon Disease Research, Department of Microbiology, 220 Nash Hall, Corvallis, Oregon 97331-3804, USA
2Environmental Conservation Division, Northwest and Alaska Fisheries Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2725 Montlake Blvd. E, Seattle, Washington 98112, USA

ABSTRACT: Unusual lesions were observed in a redstriped rockfish (Sebastes proriger) collected during a survey of marine fishes off the coast of British Columbia, Canada. This particular fish exhibited prominent hepatomegaly, with large, coalescing, multiple hemorrhages. The affected liver exhibited remarkable histological changes that, taken together, strongly suggested infection by a virus of the herpesvirus group. Multiple, multinucleated giant cells or syncytia of hepatocytes occurred throughout the liver and were associated with massive, coalescing areas of coagulation necrosis, edema, congestion and cavernous hemorrhages (peliosis hepatis) with thrombosis. In addition, the liver showed multifocal inflammation, characterized by perivascular and peribiliary cuffing of mononuclear inflammatory cells. High magnification of the syncytia revealed that the nuclei were pleomorphic, hyperchromatic, and typically contained eosinophilic to densely amphophilic inclusion bodies of varying size, closely resembling Cowdry Type A inclusions. These inclusions stained red to purple in Feulgen¹s stain, indicating presence of DNA. Electron-lucent spheres (~100 nm diameter) were observed within hepatocyte nuclei by transmission electron microscopy, suggestive of herpesvirus capsids. To our knowledge, this is the first report of a putative or confirmed herpesvirus infection in any rockfish of the genus Sebastes.

KEY WORDS: Herpesvirus · Rockfish · Liver lesions

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