Sunday, April 24, 2011

Prion infection begins after one minute of exposure

Prion infection begins after one minute of exposure

Prion infection begins after one minute of exposure

19 APRIL 2011



Scientists funded by the Medical Research Council (MRC) have shown that one minute of exposure to infecting prions is enough to begin the chain reaction of events which lead to prion disease in the brain, causing Creutzfeldt-Jakob disease, the human form of Mad Cow Disease, far quicker than previously estimated.

Understanding more about the first few minutes and the unexpected speed of prion infection in cells, demonstrated in this study, may help to explain the aggressive progression of prion diseases observed in the body and why the whole nervous system can become affected within a few weeks.

Previous studies on cultured cells had suggested that ‘prion protein misfolding’, a process which indicates the beginnings of prion infection, appears several days after exposure to infectious material. The authors of this study, published in Nature Communications have developed a new system where a tagged prion protein is introduced into cells in culture, allowing for the first time newly converted prion protein to be detected. With this system they have shown that misfolded prion protein can accumulate in under two hours, that only one minute of exposure is enough to convert a normal prion protein to its infectious form and that this occurs first on the cell surface. The work was carried out at University College London (UCL) Institute of Neurology.

Prof Sarah Tabrizi, based at the UCL Institute of Neurology, who led the study says:

“These findings provide new insights into prion infection by revealing how the infectious form of the protein can spread so quickly across the brain, and may partly explain why the whole nervous system can become affected within a few weeks. Little has been understood about the earliest events and the fundamental changes which take place when cells in the brain are exposed to prions, and hopefully this study will inform further research that goes some way to mitigating the damage caused by devastating prion infections.” An accompanying commentary “The Fast and the Furious” is also published today in Nature Reviews Molecular Cell Biology.

Ends

If you would like to get in touch with the researcher, please contact the MRC Press office on 0207 395 2345 or email press.office@headoffice.mrc.ac.uk

DOI: 10.1038/ncomms1282

Nature press release

A cell system to detect newly synthesised prions in the laboratory is reported in this week’s Nature Communications and shows that prion proteins rapidly infect cells. These findings may open new opportunities for investigating the synthesis and pathological role of prion proteins. Neurodegenerative prion diseases, such as Creutzfeldt-Jakob disease (CJD), are characterised by misfolded prion proteins, however this has been difficult to study in a laboratory setting because the proteins used to inoculate the cell cultures are identical to those that are expressed by the host cell. Sarah Tabrizi and colleagues have developed a new system where a tagged prion protein is introduced into cells in culture. This allows the study of the early features of prion infection. Using this, the team show that, in the laboratory, prions infect cells within one minute of exposure and that the cell plasma membrane is the site of the conversion of prion proteins into the misfolded form.



http://www.mrc.ac.uk/Newspublications/News/MRC007873



http://twitter.com/#!/MRCcomms/status/60762208430342145



http://transmissiblespongiformencephalopathy.blogspot.com/



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