EPITHELIOCYSTIS, A NEW INFECTIOUS DISEASE OF BLUEGILL (LEPOMIS MACROUCHIRUS)

A new infectious, benign and chronic disease, histopathologically distinct from the viral disease lymphocystis, has been found in the bluegill. The symptoms are much enlarged cells in skin and gill epithelium, filled with basophilic granules. By electron microscopy these granules were shown to be organisms with the morphological characteristics of Bedsonia (Miyagawanella). During an attempt to isolate the agent in the bluegill fibroblast cell line BF-2, a cytopathic effect somewhat resembling the lesions in vivo was found in the first passage. In later passages the agent was lost, but a true virus eliciting a distinctive fusiform cytopathic effect was recovered from these passages. The virus was found to be cytopathogenic also for the rainbow trout cell line RTG-2, but no recognizable disease could be evoked in young bluegills by inoculation of infected cell culture material. While the larger sized, non-viral organism is almost certainly the etiological agent of epitheliocystis, the role of the virus is, therefore, conjectural. Electron microscopy of thin sections has shown the virus to resemble influenza virus in morphology. © 1969 Swets & Zeitlinger.