Bungled experiments to find out if sheep catch BSE probably went wrong because samples of cow and sheep brain got mixed up in a refrigerator. That is the main conclusion from two independent audits to explain how the crucial experiment went so disastrously wrong.
The audits blame the Institute for Animal Health鈥檚 laboratory in Edinburgh for the mix-up. But the IAH鈥檚 director, Chris Bostock, says the conclusions are unfair.
Everyone agrees the experiment is dead. 鈥淭his is clearly an experiment that鈥檚 flawed and uninterpretable,鈥� said Elliott Morley, The UK鈥檚 minister for animal health.
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Determining whether sheep can catch BSE is critical in understanding the epidemic and its effect on public health. No parallel experiments were run, meaning research to find if BSE was in the UK sheep flock in the early 1990s will have to be abandoned. 快猫短视频s are now focusing on whether today鈥檚 flock is infected 鈥� the 400 animals examined so far have tested negative.
Bovine or ovine?
In 1997, IAH researchers injected what they believed to be sheep brains into mice, to see if the animals would subsequently develop BSE. The brains were originally collected in 1990 to 1992 from sheep that died of scrapie, the sheep equivalent of BSE. The researchers hoped to find out from the mice experiments whether, in some cases, the scrapie was in fact BSE.
But in October, just before the researchers presented their results, an independent analysis by the Laboratory of the Government Chemist showed that the sheep brains were actually cow brains.
The two audits published on Friday suggest that a mix up happened because pureed sheep and cow brains were stored next to one another in the same refrigerator.
The audit from Risk Solutions, a London-based consultancy, concluded that the most likely mix-up came in 1997, when technicians removed samples from the refrigerator for the mouse experiments.
鈥淭he most likely place, if a swap happened, was at the IAH,鈥� says Helen Wilkinson, author of the Risk Solutions study. She said that poor labelling of bottles might have been to blame: 鈥淭he labelling didn鈥檛 identify the species.鈥�
Old and decaying
The other audit, by the UK Accreditation Service, was less emphatic, but accused the institute of substandard labelling and record keeping.
Another possibility raised by the Risk Solutions report is that the samples got mixed up in 1992 or 1993, following the experiments for which the cow and sheep brains were originally collected.
Bostock is adamant that from the outset, he and his staff have had misgivings about the material because it was known to be old, decaying and possibly contaminated. He says that since there is now no way of finding out what happened, it鈥檚 鈥渢ime to move on to what鈥檚 happening today鈥�.
