In vCJD, conversion by the bovine prion of the host normal or cellular prion protein (PrPC) generating a human abnormal and disease-related PrP (PrPD) appears to occur in the gut-associated lymphoid tissues and to propagate to the brain following route(s) yet to be completely defined6–8. The gene discussed is PRNP; the disease is variant Creutzfeldt-Jakob disease.