Nature (Internet / Print) 01/12/06 In a secure lab in Texas, five machines are purring away quietly. Working through the night, these boxes churn out billions of malformed proteins. A seemingly odd thing to massproduce, these distorted molecules are at the heart of research into a family of diseases that destroy the brain. The equipment was devised by Claudio Soto1, a biologist at the University of Texas Medical Branch in Galveston, who works on prion protein, a naturally occurring molecule. Misfolded versions of this protein are thought to cause conditions such as mad cow disease and its human equivalent, Creutzfeldt–Jakob disease (CJD). Such abnormal prions are infectious and, when ingested, make their way to the brain, where they slowly distort the natural prion proteins, causing disease and, ultimately, death.