Study reveals role of lymph nodes in prion disease
Lymph nodes appear to play a key role in spreading low doses of prion diseases such as scrapie or bovine spongiform encephalopathy (BSE) to the central nervous system (CNS), according to new research from German scientists. The work, which was partly funded by the EU, is published in the open access journal BMC Veterinary Medicine. Prion diseases occur when abnormally folded infectious prions cause normal proteins in the brain to become similarly malformed. The brains of those infected have large numbers of tiny holes, causing them to look like sponges. There is currently no cure for prion diseases, which are always fatal. Many questions remain about how prion diseases are transmitted from one individual to another, and how the prions themselves get from the site of infection to the central nervous system. In this latest study, scientists from the Robert Koch Institute in Berlin looked at the role of lymph nodes, which are part of the body's immune system, in spreading the infectious prions within the body. The scientists infected hamsters with the prion disease scrapie by injecting different doses of the disease into the animals' feet. Some animals had nearby lymph nodes removed before being infected, and others had them removed at different points after infection. The scientists found that if a lymph node near the site of infection is removed shortly after infection with a high or medium dose of the disease, the animal still develops the disease. However, lymph node removal after infection with a low dose of the disease led to an increased survival time. Meanwhile, if a lymph node is removed four weeks before infection, a high dose causes the disease but a low dose does not. From this, the scientists conclude that for low levels of infection, the lymph nodes play an important role in the spread of prions from the site of infection to the central nervous system. They hope their findings will help scientists and doctors develop new ways of preventing and treating prion diseases. EU funding for the work came from the NeuroPrion project, which is financed under the Sixth Framework Programme's 'Food safety and quality' thematic area.
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