Scripps scientists develop new tests that identify lethal prion strains quickly and ...(cephalopathy (mad cow) and its rare huma...)

Mammalian cells normally produce what is known as cellular prion protein; during infection, the abnormal protein converts production of normal host prion protein to its infectious form. The full details of this process are still not understood.

Prions develop in distinct strains, initially characterized by incubation time and the pattern of brain damage that develops during infection. It is currently thought that strain-specific properties of prions are determined by the three-dimensional structure of the misfolded protein, although the amino acid sequence remains the same. During infection with a single type of prion, several different prion strains can be propagated indefinitely in a single host.

Some cell lines can be persistently infected by prions and show preference for certain strains, Mahal said. One intriguing finding of our new study is that a cell lines ability to replicate a particular prion strain is a trait that varies significantly among the members of the cell population-even sibling cell lines may show different relative susceptibilities to various prion strains.

This suggests that the capacity of a cell line to replicate a particular prion strain is controlled epigenetically without any changes to the DNA sequence, she said.

Another fascinating question raised by the study is how cells come to distinguish between prion strains; that is, between the various proteins that differ only in the way they are folded. The exact nature of that recognition process is now the target of a new Scripps Research study using the Cell Panel Assay.

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