Path morphological alterations in sheep with scrapie: light and electron microscopy

Abstract

In Russia sporadic сases of scrapie in sheep of Romanov breed registered from the beginning of 1980s. However the scrapie agent characteristics have not been studied. In case the BSE agent is introduced into Russia it may be recognized as sheep scrapie, while the BSE agent is very dangerous from social and economic points of view.
 
 The purpose of investigations. To study path-morphological and submicroscopic changes in ovine brain tissues in experimental infections with scrapie agent (BT-91 strain) isolated from Romanov sheep.
 
 Materials and methods. The BT-91 strain isolated from a Romanov sheep was used in our experiments. Eight merinos lambs were used. The animals were orally infected with partially purificated brain homogenate from a sheep with scrapie. Pathological changes in the brain tissues were studied using routine methods of light and electron microscopy.
 
 Results. The incubation period was on average 568 days. The clinical symptoms were typical of CNS infection. Pathogistological changes were seen as spongiform encephalopathy in light microscopy. Ultrastructural changes in the brain tissues were seen as mass formations in the nerve cell cytoplasm multivesicular structures, autophagosomes, membrane changes, and dystrophy of cell organelles.
 
 Conclusion. The BT-91 strain causes clinical symptoms and histopathological changes in the CNS of sheep typical to classical scrapie.