Detection of Rabies Virus and its Pathological Changes in Brain of Buffaloes in Egypt

Abstract

This study aims to detect the rabies viral antigen in the brains of naturally infected buffaloes by immunofluorescence and electron microscope, identify the histopathological and ultrastructure alterations of infected brain concerning the changes in endothelial cells of the blood barrier and evaluate rabies cycling in Egypt. Necrotic brains were carefully collected from ten expected to be rabid infected buffaloes, evaluated for gross lesions of rabies disease and microscopically examined for viral antigen expressions and histopathological changes. The results of the gross examination of the collected brains showed the presence of severe congestions in both meningeal and cerebral blood vessels, as well, hemorrhage and edema in cerebrum and cerebellum. The immunofluorescence and electron microscopes revealed the presence of the rabies viral antigen, Negri bodies and the characteristic bullet shape of the viral particles. Histopathological examination estimated the presence of intracytoplasmic inclusion bodies (Negri bodies) in the Purkinje cells of cerebellum, vasculitis, necrotic endothelial cells and marked neuronal necrosis with satellitosis and neuronophagia. The electron microscopic reported vacuolated endothelial cells, clumped nuclear chromatin of loss tight junctions, and vasogenic edema with consistent erythrocytes leakage in the infected brain. We concluded that rabies infection of buffaloes could be easily diagnosed in the laboratory by fluorescence and electron microscopes. Pathologically, rabies infection could cause injuries of the endothelial cells with disruption of blood brain barrier causing detrimental alterations. Special attention should be given to stray dogs and outdoor rearing of buffaloes