Acute lymphoblast leukemia in sheep induced by inoculation of bovine leukemia virus: diagnostic electron microscopic...

Six control lambs were inoculated with Tris buffer, 7 lambs were inoculated with an early passage of bovine leukemia virus (B.L.V.) culture, and 7 lambs with a late passage B.L.V. All experimental lambs were positive with the agar gel immunodiffusion assay (AGID) within 3 months of inoculation and remained positive throughout the 8-year duration of the experiment. The earliest onset of leukemia was at 14 months and the latest was at 44 months after inoculation. Five lambs died with leukemia, two were inoculated with early passage, and three were inoculated with late passage of B.L.V. Eight years after the inoculation, the remaining nine inoculated lambs were clinically normal. The diagnostic ultrastructural morphology of the leukemic lymphoblasts in this study were characterized by hand-mirror cells, multiple nucleoli, irregular nuclear contour with deep indentions, electron-dense granules in the euchromatin, and nuclear cytoplasmic pockets, nuclear myelin figures, mitochondrial variation in size and density, disruption of rough endoplasmic reticulum, and increased ribosomal density. This study shows abundant cytoplasmic processes of hairy cell leukemia. The nuclei of the leukemia lymphoblasts showed electron-dense granules of varying sizes, which were not seen in any of the normal lymphoblasts.