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Researchers have gotten infectious prions from one species to turn normal prion proteins from a different species into infectious ones in a test tube. The technique will prove a valuable tool for understanding how prions cross species barriers. The brain tissue of a person with Creutzfeldt-Jakob disease has a sponge-like appearance. Image courtesy of Teresa Hammett, Centers for Disease Control and Prevention. The normal prion protein is found on the surface of many types of cells, mostly brain cells. Scientists dont understand what normal prion protein does, but most believe that abnormal prions, which clump together and accumulate in brain tissue, are the cause of brain damage in a group of rare, fatal brain diseases called transmissible spongiform encephalopathies (TSE). viagra in britain viagra treatment migraine headache generic viagra u purchasing viagra on line how do you prone cialis
