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United States Department of Agriculture

Agricultural Research Service

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BSE ("mad cow disease") and other TSE diseases
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Transmissible Spongiform Encephalopathy diseases (TSEs) include Bovine Spongiform Encephalopathy (BSE, aka "mad cow disease"). TSEs are transmitted orally, through ingestion of infected/contaminated material. Upon eating BSE-contaminated beef, humans may contract a TSE called variant Creutzfeldt-Jakob Disease (vCJD). However, even though hundreds of millions of Europeans were exposed to BSE, less than 200 developed vCJD. The BSE epidemic was ended by banning beef by-products from feed used for sheep and cattle. Control of similar TSEs, such as scrapie in sheep and Chronic Wasting Disease in deer and elk, will require tests with improved sensitivity. Current tests are useful only on grossly infected animals, and only after slaughter. We are developing new methods that can be used on live animals, to diagnose disease before either symptoms or transmission can occur. We are also developing tests for use on agricultural commodities and surfaces. (CRIS 5325-32000-008-00D)

Mass spectrometry – Maximum sensitivity will be necessary for a test capable of diagnosing TSE in live animals before symptoms occur. Our mass spec approach delivers unprecedented sensitivity and provides clues about subtle differences between TSE strains. Our publications on this research include: Mass Spectrometric detection of attomole amounts of the prion protein by nano LC/MS/MS

In vitro conformation conversion – TSE disease is associated with conversion of a host protein (PrP) from its normal form (PrPc) to a disease-related conformation (PrPd). By studying this reaction we learn about the biomolecules and processes involved in disease. We have published on this technique here: Sonication induced intermediate in prion protein conversion

Biodiesel – The beef by-products now banned from animal feed are high in fats, which can be converted into biodiesel using a process that destroys about 99.9999% of the infectivity of TSEs. We recently published this observation at: Prion infected meat-and-bone meal is still infectious after biodiesel production

Pathophysiology – TSEs are very poorly understood pathogens. For example, they appear to completely lack DNA or RNA genetic material, yet they reproduce within a host, and cause identical disease upon transmission to another host. Our recent observations on the pathophysiology of TSEs include this publication: Inoculation of scrapie with the self-assembling RADA-peptide disrupts prion accumulation and extends hamster survival

PrP null mouse – Most diagnostic and detection tests are based on antibodies generated in cultured cells originally derived from normal mice producing plenty of PrP protein. In collaboration with the laboratory of Stanley Prusiner at the University of California San Francisco we developed strains of genetically modified mice lacking the PrP protein, and used them for creation of improved antibodies for more sensitive tests. This work has been submitted for peer-review and publication.

The December 2004 issue of Agricultural Research magazine includes a feature article on ARS work on BSE, including some of our own research. You can read it online here.

 


Last Modified: 3/10/2011
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