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. Last Updated: 07/27/2016

Host's Cells Attack Brain

LONDON -- German scientists believe a cell that normally helps the body fight bacteria may trigger the degeneration of the brain caused by the group of diseases including "mad cow disease," the science journal Nature reported Wednesday.

Bovine spongiform encephalopathy (mad cow disease) and Creutzfeldt-Jakob disease, its human form, are caused by infectious, abnormal forms of the protein prion.

These modify the harmless form of prion that occurs naturally in the host, triggering an infection that spreads through the brain in a chain reaction.

But scientists had been unable to explain what actually caused the neurodegenerative reaction that bores holes through victims' brain tissue, causing dementia, disability and then death.

Researchers from the University of Goettingen in Germany said the culprit might be a type of scavenging cell called microglia, which usually fights infection and bacteria.

When stimulated by a prion, microglia release oxidant chemicals which the researchers believe may destroy neural tissue.