The alternative view that a virus causes spongiform encephalopathies of the brain, such as bovine spongiform encephalopathy and Creutzfeldt-Jakob disease, rather than prion proteins, which are normally produced throughout life, was bolstered today in a new study by Yale School of Medicine researchers.
The report published online January 29 in the Proceedings of the National Academy of Sciences provides evidence that a virus causes these diseases, which are manifested by devastating holes, or sponge-like spaces, in the cerebral cortex. The conclusions counter the now conventional view that abnormally folded prion proteins are infectious, and instead suggests that abnormal prion proteins are late stage footprints left by the virus.
The lead author, Dr. Laura Manuelidis, professor and section chief of neuropathology, infected cell lines with either scrapie or CJD agents. Examining the cultures using electron microscopy, Manuelidis and her co-authors found an abundance of 25 nm virus-like particles. They also found that the particles did not bind antibodies for the prion protein, indicating they were not composed of prion protein.
The development of the particles was independent of pathological changes or neuronal specialization, and preparations with an abundance of these particles correlated with high levels of infectivity, whereas the presence of prion proteins did not.