Comparison of the neuropathological characteristics of bovine spongiform encephalopathy (BSE) and variant Creutzfeldt-Jakob disease (vCJD) in mice

Bovine spongiform encephalopathy (BSE) and variant Creutzfeldt-Jakob disease (vCJD) belong to a group of diseases called the transmissible spongiform encephalopathies (TSEs). Transmission studies in inbred mice (strain typing) provided overwhelming evidence that vCJD arose from BSE. In this study, we compare the patterns of neuropathology in a panel of three inbred mouse strains (RIII, C57BL and VM) and one cross (C57BL x VM) infected with either vCJD or BSE. For each mouse strain, patterns of abnormal prion protein (PrPres ) deposition, astrocytosis and vacuolation were similar in the vCJD- and BSE-challenged mice. Prion protein (PrP)-positive plaques were prominent in the VM and C57BL x VM mice in addition to diffuse PrPres accumulation, whereas only diffuse PrPres labelling was observed in the RIII and C57BL mice. The hippocampus was targeted in all mouse strains, as was the cochlear nucleus in the medulla, both showing consistent severe vacuolation and heavy PrPres deposition. Although the targeting of PrPres was similar in the BSE- and vCJD-infected brains, the amount and intensity of PrPres observed in the brains treated with formic acid during fixation was reduced considerably. The distribution of astrocytosis was similar to the targeting of PrPres deposition in the brain, although some differences were observed in the hippocampi of mice challenged with vCJD. We conclude that there are no significant differences in the targeting of neuropathological changes observed in the BSE- and vCJD-infected mice, consistent with the previous evidence of a link between BSE and vCJD.