Apoptosis in natural rabies virus infection in dogs

Abstract

Introduction: In the present study apoptosis was investigated in the cornu ammonis and cerebellum of 10 dogs naturally infected with rabies virus. Diagnosis of rabies was based on the results of fluorescent antibody staining and experimental inoculation. Material and Methods: The paraffin tissue sections were stained with haematoxylin and eosin, avidin-biotin complex peroxidase (ABC-P), and terminal deoxynucleotidyl transferase biotin-dUTP nick end-labelling (TUNEL) methods. Results: Histopathological examination revealed encephalomyelitis of varying severity and the presence of Negri bodies. Dense rabies antigens were determined in the motor neurons with ABC-P method. On the other hand, Bcl-2 protein and Box protein gave positive reaction in seven and five cases, respectively. TUNEL staining demonstrated very marked apoptotic changes in the nuclei of neurons localised deep in the substantia alba of the cerebellum. Similar changes were also determined in perivascular mononuclear cells and glia cells within the substantia alba. No apoptopic changes were found in the motor neurons of the cornu ammonis. Conclusion: The absence of apoptotic changes in the neurons was considered to be the consequence of the necrotic changes that developed in these neurons.