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| The results of the research are published in the online edition of the Proceedings of the National Academy of Sciences |
This could help improve the diagnosis of diseases such as bovine spongiform encephalopathy in cattle and scrapie in sheep, and to gain a better understanding of how they develop.
The researchers who designed the tests say they are highly accurate and can distinguish several strains of prions within various cell lines quickly.
The in vitro "Standard Scrapie Cell Assay" measures the level of prion infectivity in less than two weeks. The current standard method, which involves injecting prion strains into different lines of mice, can take months or even years to measure the time it takes for the disease to become evident.
"The Standard Scrapie Cell Assay vastly accelerates the measurement of prion infectivity and the determination of those cell lines that are able to sustain high infection rates of some prion strains," said Dr Sukhvir P Mahal of the Scripps Research Institute (SRI) in Florida. "The current test, which takes anywhere from 150 to 250 days and involves large numbers of laboratory mice, is slow, imprecise, and expensive," she added.
The other test, "Cell Panel Assay", exposes cells to prions and then uses automated imaging equipment to identify and count the cells that have been infected. It is based on SRI research that has shown that the responses of four different prion-susceptible cell lines to different prion strains vary.
Dr Mahal said: "Some cell lines can be persistently infected by prions and show preference for certain strains. 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."
More research is needed before these tests are ready to market. The scientists plan to determine how cells are able to distinguish different prion strains. This research is already under way for the Cell Panel Assay. The results of the research have been published in the online edition of the Proceedings of the National Academy of Sciences.
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