Friday, January 12, 2007

Building better beef   posted by p-ter @ 1/12/2007 06:31:00 PM

Mad cow disease is caused by the misfolding of a protein called the prion protein. One might imagine, then, that a cow without said protein would be resistant to mad cow. And indeed, that is the case:
Prion diseases are caused by propagation of misfolded forms of the normal cellular prion protein PrPC, such as PrPBSE in bovine spongiform encephalopathy (BSE) in cattle and PrPCJD in Creutzfeldt-Jakob disease (CJD) in humans. Disruption of PrPC expression in mice, a species that does not naturally contract prion diseases, results in no apparent developmental abnormalities. However, the impact of ablating PrPC function in natural host species of prion diseases is unknown. Here we report the generation and characterization of PrPC-deficient cattle produced by a sequential gene-targeting system. At over 20 months of age, the cattle are clinically, physiologically, histopathologically, immunologically and reproductively normal. Brain tissue homogenates are resistant to prion propagation in vitro as assessed by protein misfolding cyclic amplification. PrPC-deficient cattle may be a useful model for prion research and could provide industrial bovine products free of prion proteins.
Will it one day be considered irresponsible to produce beef that is not genetically modified?