Comparison of spongiform lesions in experimental scrapie and rabies in skunks

Abstract

Striped skunks were inoculated intracerebrally with the scrapie agent (suspension of brain from a naturally infected Suffolk sheep) or intramuscularly with street rabies virus (suspension of salivary glands from naturally infected skunks). Those given the scrapie agent developed clinical signs of weakness, posterior ataxia, and emaciation after incubated periods of 8 to 23 months. Those inoculated with rabies virus developed clinical signs of rabies (aggressive behavior, hyperexcitability, ataxia and paralysis) after incubation periods of 20 to 62 days. The gross lesions in the brains of the skunks given the scrapie agent consisted of marked atrophy of the thalamus and moderate atrophy of the cerebrum. No gross lesions occurred in the rabid skunks. Histologically, the type of spongiform lesion in rabies was the same as that in scrapie. However, spongiform change of rabies infected brains was less extensive (only rarely affected the basal ganglia, hippocampus or hypothalamus) than that of brains infected with the scrapie agent and was characterized by fewer numbers of small vacuoles (as a proportion of total number of vacuoles) than occurred in scrapie spongiform change.

Experimental Scrapie in White Swiss Mice

“…mouse i. c. LD5,/30 mg of sheep scrapie brain which compares to HADLOW (1 1). Atrophy of the thalamus and cerebral cortex occurred in scrapie in skunks and Creutzfedt-Jakob disease (CJD) (5,12). Atrophy of the midbrain occurred also in human motor neuron disease (MND) (9).…”

Pathology

“…However, with fixed virus infection using intracerebral inoculation in adult animals or using any route of inoculation in immature animals, widespread neuronal injury with cytoplasmic condensation, multivesiculation, increase in lysosome content, intercellular edema, and cell death are frequently seen (Miyamoto & Matsumoto, 1967;Murphy, 1977). This spongiform change closely resembled that of traditional spongiform encephalopathies, although the vacuolation was less extensive than that found in skunks experimentally inoculated with scrapie agent (Bundza & Charlton, 1988). This spongiform change closely resembled that of traditional spongiform encephalopathies, although the vacuolation was less extensive than that found in skunks experimentally inoculated with scrapie agent (Bundza & Charlton, 1988).…”

A peep into detection of rabies in 20 th century

“…No significant gross changes were reported in brain, ganglia and salivary glands in rabies [3,13,14]. Gross lesions in experimentally produced rabies in sheep by using street rabies virus were non-specific [8].…”

“…Skunks inoculated intra muscularly with street rabies virus, revealed moderately extensive spongiform lesions that rarely affected basal ganglia or hippocampus. Spongiform lesions were characterized by fewer numbers of small vacuoles [14].…”