Cellular prion protein (PrPC) is present in the healthy adult brain. It is a presumably essential membrane protein but its cellular function is unclear. Like Ice-9 - the fictitious water allotrope in Kurt Vonnegut's Cat's Cradle, which "taught the atoms a novel way in which to stack, lock and crystallize until the oceans turned to ice" - cellular prion protein can, in a rare event, adopt a pathogenic and 'contagious' shape, PrPSc, which causes mad cow disease or Bovine Spongiform Encephalopathy (BSE). New variant Creutzfeldt Jakob Disease (vCJD) is the human malady attributed to eating beef tainted with BSE. In comparison to the UK epidemic (at the peak of which 37,280 cases of BSE were reported in the single year 1992), the emergence of four North American mad cows since May 2003 is minor yet still alarming. This work examines the USDA's response to indigenous BSE as manifested in "The Final Rule" (9 CFR 93-96, Jan 4, 2005) and questions whether current regulations are stringent enough to keep PrPSc out of cattle feed and human food.
Sheila Healy is a CISAC Science Fellow. She is currently analyzing USDA policy addressing Bovine Spongiform Encephalopathy (BSE) or mad cow disease. She recently finished a postdoctoral appointment in Stanley Prusiner's laboratory in the Department of Neurology at the University of California, San Francisco. There she studied the molecular and structural requirements for the conversion of cellular prion protein to its pathogenic form, the agent that causes BSE. She holds a doctoral degree in biochemistry and molecular and cellular biology from the University of Arizona.