The deadly malformed proteins responsible for mad cow disease and similar neurodegenerative illnesses in people and other animals may spread between cells using microscopic bubbles, a new study suggests.
These bubbles, known as exosomes, are spit out of immune cells and a variety of other cell types. Some researchers contend that these mobile balloons enable cells to communicate with each other or exchange material. A few investigators even suggest that HIV, the AIDS virus, exploits exosomes to spread copies of itself among cells (SN: 12/6/03, p. 363: Tiny Bubbles).
Prions, the infectious proteins that cause mad cow disease, travel in exosomes, Graça Raposo of the Curie Institute in Paris and her colleagues now conclude. In an upcoming Proceedings of the National Academy of Sciences, they report that prions are secreted from cells in association with proteins and cell membrane material characteristic of exosomes.