Mike
Well-known member
Species barrier
Most experts believe that the sudden appearance of vCJD in 1996 - a disease that causes sponge-like holes in the brain - has its origins in diseased cattle.
They hypothesised that both BSE and vCJD were caused by rogue prion proteins that jumped the species barrier from cows into humans. But although various studies have appeared to support this linkage, conclusive proof has remained elusive.
Some countries are still reluctant to import British beef
Now researchers from the University of California, San Francisco, and the UK National CJD Surveillance Unit, Scotland, have reported striking similarities between the two diseases. The scientists conducted experiments with mice genetically-altered to produce the same prions naturally found in cows.
They discovered, not unexpectedly, that there was no species barrier between the mice and cows. Diseased brain tissue injected into the mice produced symptoms in 250 days, the same incubation period experienced by cattle with BSE.
A second group of mice given prions from the first group also became sick in virtually the same period of time. But the big surprise came when human brain tissue infected with the prions that cause vCJD was injected into the mice.
'Indistinguishable' identities
Once again there was no apparent sign of a species barrier, but, more significantly, vCJD had virtually the same incubation period in the mice as BSE.
The pattern of brain damage was also identical. The results suggest that BSE and vCJD are interchangeable. Introduced into transgenic mice, vCJD prions assumed an identity "indistinguishable from BSE prions", the researchers write in the PNAS.
BSE is thought have its origins in sheep
The similarities not only force the scientists to the conclusion that BSE must be the cause of vCJD, but make them worry that many more people than previously thought could fall ill as a result of eating infected meat.
The research team also found their altered mice were highly susceptible to infection with the sheep prion disease scrapie, although this produced a different biological pattern.
Scientists suspect BSE may have originated in cattle as a result of feeding them sheep remains infected with scrapie. The transgenic mice used in this study could be used to check this linkage, the team say.
PNAS
Neurology at UCSF
The Ministry of Agriculture, Fisheries and Food
UK CJD surveillance unit
Most experts believe that the sudden appearance of vCJD in 1996 - a disease that causes sponge-like holes in the brain - has its origins in diseased cattle.
They hypothesised that both BSE and vCJD were caused by rogue prion proteins that jumped the species barrier from cows into humans. But although various studies have appeared to support this linkage, conclusive proof has remained elusive.
Some countries are still reluctant to import British beef
Now researchers from the University of California, San Francisco, and the UK National CJD Surveillance Unit, Scotland, have reported striking similarities between the two diseases. The scientists conducted experiments with mice genetically-altered to produce the same prions naturally found in cows.
They discovered, not unexpectedly, that there was no species barrier between the mice and cows. Diseased brain tissue injected into the mice produced symptoms in 250 days, the same incubation period experienced by cattle with BSE.
A second group of mice given prions from the first group also became sick in virtually the same period of time. But the big surprise came when human brain tissue infected with the prions that cause vCJD was injected into the mice.
'Indistinguishable' identities
Once again there was no apparent sign of a species barrier, but, more significantly, vCJD had virtually the same incubation period in the mice as BSE.
The pattern of brain damage was also identical. The results suggest that BSE and vCJD are interchangeable. Introduced into transgenic mice, vCJD prions assumed an identity "indistinguishable from BSE prions", the researchers write in the PNAS.
BSE is thought have its origins in sheep
The similarities not only force the scientists to the conclusion that BSE must be the cause of vCJD, but make them worry that many more people than previously thought could fall ill as a result of eating infected meat.
The research team also found their altered mice were highly susceptible to infection with the sheep prion disease scrapie, although this produced a different biological pattern.
Scientists suspect BSE may have originated in cattle as a result of feeding them sheep remains infected with scrapie. The transgenic mice used in this study could be used to check this linkage, the team say.
PNAS
Neurology at UCSF
The Ministry of Agriculture, Fisheries and Food
UK CJD surveillance unit