Mm. Robinson et al., EXPERIMENTAL-INFECTION OF CATTLE WITH THE AGENTS OF TRANSMISSIBLE MINK ENCEPHALOPATHY AND SCRAPIE, Journal of Comparative Pathology, 113(3), 1995, pp. 241-251
Cattle are susceptible to experimental infection with the Stetsonville
isolate of the transmissible mink encephalopathy (TME) agent. To dete
rmine if they are susceptible to other TME isolates, two groups of cal
ves were inoculated intracerebrally with homogenate of mink brain cont
aining the Hayward isolate or the Blackfoot isolate. For comparison, a
third group was inoculated with a brain homogenate from a steer infec
ted with the Stetsonville isolate in its primary cattle passage and a
fourth group was inoculated with a pool of brain homogenate from three
cattle experimentally infected with a sheep and goat scrapie agent in
its primary cattle passage. Clinical signs of neurological disease ap
peared in each steer of every group between 15 and 25 months after ino
culation. An encephalopathy characterized by severe spongiform change
and pronounced astrocytosis occurred in the three groups inoculated wi
th the TME agent. In contrast, the neurohistological changes in the st
eers inoculated with the cattle-passaged scrapie agent were slight and
subtle. Analysis of the octapeptide repeat region of the bovine prote
ase-resistant protein (PrP) gene showed that variations in incubation
period, clinical signs, and neurohistological changes were unrelated t
o the homozygous or heterozygous condition of six or six/five octapept
ide repeats. (C) 1995 Academic Press Limited