Pathogenesis of rabies in dogs inoculated with an Ethiopian rabies virus strain. Immunofluorescence,histologic and ultrastructural studies of the central nervous system

Summary Dogs were inoculated with either an Ethiopian or Mexican rabies virus strain. The distribution of viral antigen and lesions were studied by immunofluorescence, histologic and electron microscopic techniques. In all dogs inoculated with the Ethiopian rabies virus strain, tremendous whorls of filamentous fluorescing aggregates were observed throughout the brain; these were not observed in dogs inoculated with the Mexican virus.Lesions consisted of neuronal degeneration and neuronophagia, associated with large inclusion bodies and widespread inflammation in dogs inoculated with the Ethiopian isolate. All observed portions of the brain and spinal cord were affected. In general, lesions were much less severe with the Mexican isolate. Occasional astrocytes were observed to have inclusions in dogs inoculated both with the Ethiopian and Mexican strains.Most neurons examined electronmicroscopically showed signs of infection, varying from a small granular or finely fibrillar viral matrix to numerous matrices accompanied by prolific numbers of virus particles occupying much of the perikaryon. These were found in all dogs inoculated with the Ethiopian strain but were rare with the Mexican isolate. Viral budding occurred from membranes of the rough endoplasmic reticulum, outer lamella of the nuclear envelope, and rarely from the plasma membrane.With 15 FiguresThis work was done while the senior author (Visiting Scientist) was being supported by the Swedish Aid for Research Cooperation with Developing Countries Project 77/89 A 9–49 U-forsk, through the Department of Bacteriology and Epizootology, Biomedicum, P.O. Box 583, S-75123 Uppsala, Sweden.