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Transmissions to mice indicate that 'new variant' CJD is caused by the BSE agent
M E Bruce1, R G Will, J W Ironside
1Institute for Animal Health, BBSRC/MRC Neuropathogenesis Unit, Edinburgh, UK. moira.bruce@bbsrc.ac.uk
Abstract:
There are many strains of the agents that cause transmissible spongiform encephalopathies (TSEs) or 'prion' diseases. These strains are distinguishable by their disease characteristics in experimentally infected animals, in particular the incubation periods and neuropathology they produce in panels of inbred mouse strains. We have shown that the strain of agent from cattle affected by bovine spongiform encephalopathy (BSE) produces a characteristic pattern of disease in mice that is retained after experimental passage through a variety of intermediate species. This BSE 'signature' has also been identified in transmissions to mice of TSEs of domestic cats and two exotic species of ruminant, providing the first direct evidence for the accidental spread of a TSE between species. Twenty cases of a clinically and pathologically atypical form of Creutzfeldt-Jakob disease (CJD), referred to as 'new variant' CJD (vCJD), have been recognized in unusually young people in the United Kingdom, and a further case has been reported in France. This has raised serious concerns that BSE may have spread to humans, putatively by dietary exposure. Here we report the interim results of transmissions of sporadic CJD and vCJD to mice. Our data provide strong evidence that the same agent strain is involved in both BSE and vCJD.
Insights
Bovine spongiform encephalopathy (BSE) and new variant Creutzfeldt-Jakob disease (vCJD) share the same prion strain. This finding, based on mouse models, provides evidence of BSE transmission to humans and across species.
Area of Science:
- Neuroscience
- Veterinary Medicine
- Infectious Diseases
Background:
- Transmissible spongiform encephalopathies (TSEs) are prion diseases with distinct strains.
- Strain characteristics are identified by incubation periods and neuropathology in mice.
- Bovine spongiform encephalopathy (BSE) is a notable TSE in cattle.
Purpose of the Study:
- To investigate the strain characteristics of the agent causing BSE.
- To determine if the BSE agent strain is present in other species, including humans with new variant Creutzfeldt-Jakob disease (vCJD).
- To provide evidence for interspecies TSE transmission.
Main Methods:
- Experimental transmission of TSE agents to inbred mouse strains.
- Analysis of incubation periods and neuropathological profiles in infected mice.
- Comparison of disease patterns from BSE, feline TSE, ruminant TSE, sporadic CJD, and vCJD.
Main Results:
- The BSE agent produces a consistent disease signature in mice, maintained through experimental passage.
- This BSE signature was identified in TSEs from domestic cats and exotic ruminants, indicating interspecies spread.
- Transmissions of sporadic CJD and vCJD to mice suggest the same agent strain is involved in both conditions.
Conclusions:
- The study provides the first direct evidence of accidental TSE spread between species, linked to BSE.
- The findings strongly suggest that the agent strain responsible for BSE is also responsible for new variant Creutzfeldt-Jakob disease (vCJD) in humans.
- This research highlights the potential public health risks associated with BSE transmission to humans, likely through dietary exposure.