Glowing molecule detects prion diseases
4 December 2007
An international team of researchers has developed a
method of identifying prion and other defective-protein diseases using a
fluorescent molecule that changes colour according to the disease present.
Prions are the infectious compounds behind diseases such as mad cow
diseases, while other defective-protein diseases are implicated in diseases
such as Alzheimer's.
The method, reported in the journal Nature Methods
(1), is based on a fluorescent molecule, a so-called conjugated
polymer, which was developed at Linköping University in Sweden.
research team infected genetically identical laboratory mice with BSE,
scrapie (which afflicts sheep), and CWD (chronic wasting disease or 'mad elk
disease', which is epidemic in the central US) for several generations in a
Gradually, new strains of prions emerged, making the diseases more fatal
to the mice. Tissue samples from mice were examined using a fluorescent
molecule that binds with prions. This is detected by a shift in colour.
By tweaking the molecule, the team has been able to get it to show
different colours depending on the strain of the prion — each of which has a
This is an important difference compared with other
techniques used to find prions, such as antibodies and the well-known stain
The technique has also proven to work well on tissue sections from dead
animals, such as cows infected with BSE. Now the scientists want to move on
and look for alternative sample-taking methods for diagnosing and tracking
prion diseases in humans in early stages.
Mad cow disease (BSE) has caused
the death of more than 200,000 cattle and 165 people in the UK, but has now
abated. Other prion disorders, however, are on the rise, and there is
concern that new strains will infect humans. Prions are not readily
transmittable from species to species, but once they have broken through the
species barrier they can rapidly adapt and become contagious within the
Intensive work is now underway to find new, more sensitive methods for
detecting these potentially deadly protein structures and distinguish
between various strains.
The new method could be useful for screening
blood products, since there is a risk that people can be carriers of prions
without having any symptoms of disease.
In the UK it was discovered that 66 people had received blood from blood
donors who were infected with the human form of BSE (a variant of
Creutzfeldt-Jakob’s disease, vCJD), and among them, four individuals have
been shown to be infected (source: Health Protection Agency, Jan. 2007).
“Using our methods, we can directly see the structure of the prions and
thereby deduce the disease,” says Peter Nilsson, one of the lead authors of
the article. Nilsson also developed the technique as a doctoral student at
Linköping University and now, as a post-doctoral fellow with Professor
Adrian Aguzzi’s research team in Zürich, has been applying the technology to
“For us researchers it is truly exciting to use this technique to
understand more about both prions and other defectively folded proteins that
give rise to similar disorders, such as Alzheimer’s,” says Peter
Hammarström, co-author and research director of the prion laboratory at
1. Christina J Sigurdson, K Peter R Nilsson, Simone
Hornemann, Guiseppe Manco, Magdalini Polymenidou, Petra Schwartz, Mario
Leclerc, Per Hammarström, Kurt Wüthrich, and Adriano Aguzzi. Prion strain
discrimination using luminescent conjugated polymers. Nature Methods - 4,
1023-30 (2007). Published online: 18 November 2007; | doi:10.1038/nmeth1131
Save this page on del.icio.us