spongy mess. When injected into mice, synthetic prion punch tiny holes in the brain tissue ( right ) compared to healthy animals ( left ).
Wang Fei et al. science
Since 1982, neurologist and biochemist Stanley Prusiner first claimed to purify proteins to pray, controversy has dogged the field. Do prion - misfolded versions healthy protein related to mad cow disease and other neurological diseases - infect and cause disease all on their own? Or did they need a partner in crime? Some say a new study provides the strongest evidence to date for the assumption "protein only". But die-hard skeptics remain unconvinced.
thereFive years, Prusiner reported the first important evidence that prions act alone. He and his colleagues from the University of California, San Francisco, injected the brains of mice with prions they had created in the laboratory by folding of the normal prion protein, known as PrP. The mouse is down with a neurological disease. But the work had its limits: Rodents took over a year to get sick, and they had been bred to produce huge amounts of PrP, raising questions about whether they were susceptible to prion disease anyway
Jiyan Ma ,. biochemist at Ohio State University in Columbus, with colleagues there and in China, solved both problems by coaxing prion misfold as he believes they do naturally. Instead of refolding of healthy prion protein PrP, in amyloid fibrils, which have been linked to the disease, the team PrP combined with various mixtures of lipids - fatty molecules judged misfold in the cell. "This is like cooking," Ma said, getting the right combination of ingredients.
Finally, the group Ma came up with a recipe that looked promising and injected into the brains of 15 normal mice. In 130 days, all the animals developed what looked like a prion disease contracted their heads, they lost muscle tissue, and they became lethargic. The animals died a few months later. Control animals injected with a solution "harmless" remained healthy, the team reports online today in Science .
To ensure that prion was that made them sick mice, Ma conducted a series of tests to prove an infectious disease. Dissect the brains of animals, he and his colleagues tissue extract and injected into the brains of healthy animals. These animals are so sick as the previous group -. And all showed evidence of prion
This is something "we and others have tried to do for a while," said Claudio Soto, a neuroscientist at the University of Texas Medical School at Houston. "This is proof of the protein only hypothesis."
for those who have already been convicted, the paper still "change the rules," says Adriano Aguzzi, a neuropathologist at the University of Zurich in Swiss . This is because Ma and his colleagues were able to create large amounts of synthetic prion, which Aguzzi believes it will be possible to study the prion structure in greater detail than was previously possible.
But will it convince the skeptics? "On the face of it, it looks like they have turned golden tin," said Laura Manuelidis, neuropathologist at Yale University who has long doubted that prions cause disease by themselves. ( she believes that viruses are involved) But Manuelidis feared that my claims as a success. - the speed with which the animals became ill. - rather suggests that something is wrong she wonders if the animals have actually contracted scrapie ., another prion disease, because of laboratory contamination Ma totally rejects this possibility: "There is no way" the mice could have contracted a natural prion disease scrapie as he said, because the laboratory did not work with prion natural
- Correction.
The story incorrectly states that the laboratory Ma has never worked with prions naturally. In fact, he did, but not during the past two years conducting the experiments described here.
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