Immunohistochemical detection of rabies virus antigen in the cardiac ganglia of dogs in paraffin sections

The hearts of five naturally infected rabid dogs were studied by immunohistochemistry on paraffin sections using a monoclonal antibody and the peroxidase labelled streptavidin-biotin method to detect rabies ribonucleoprotein. In all cases distinct small granular and ring-shaped antigen deposits were found within the nerve cells of the cardiac ganglia thus reflecting the early centrifugal spread of virus along the pathway of the vagal nerve to the heart. Histologic findings consisted only of single small eosinophilic inclusions in some nerve cell bodies. These findings may be of diagnostic value.