Prion proteins are responsible for a class of neurodegenerative disorders, including Creutzfeldt–Jakob disease, in which misshapen prions cause other prions to misfold and form fibrous aggregates. Researchers at the University of Texas Southwestern Medical Center in Dallas have found a human protein that behaves like a disease-causing prion to trigger an antiviral immune response.

Zhijian Chen and his group studied virus-infected human cells and focused on the protein MAVS, which is activated when viral RNA binds to certain cell receptors. They found that, on infection, MAVS molecules form aggregates — similar to those of disease-linked prions — that convert more MAVS to aggregates. This activates MAVS to trigger the antiviral response. The authors suggest that this conversion process serves to amplify this immune response, boosting its sensitivity to viral infection.

Cell 146, 448–461 (2011)