Experimental transmission of human subacute spongiform encephalopathy to small rodents. I. Clinical and histological observations.

Experimental transmission of subacute spongiform encephalopathy from three human cases to small rodents is reported. The first case with atypical CJD with spongiform change, kuru plaques, and leukomalacia was transmitted directly to mice, rats, and guinea pigs and indirectly to hamsters and Mongolian gerbils through rats. From two other typical SSE cases the disease was also successfully transmitted; from he second case to mice and rats, and from the third case to guinea pigs. Brain showed the highest infectivity; the spleen, liver, blood, and cerebrospinal fluid of diseased animals were also infective. Intracerebral inoculation was the route for the fastest transmission, followed by intrathecal, intraperitoneal, submucosal, and subcutaneous routes. The incubation periods and clinical features were characteristic in each inoculated species and did not vary within several passages, except for the shortening of incubation period from the first to the second passage. Histologically, a marked spongy state and proliferation of astrocytes were observed in all diseased animals, though the distribution of the lesion was peculiar to each species. The severe lesion in the white matter in mice was similar to that seen in mice inoculated with scrapie and also to that seen in the first case.