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Genetic scientists develop prion-free cattle
Cattle appear immune to BSE

Scientists have created prion-free cattle that appear to be immune to bovine spongiform encephalopathy, or BSE.

Twelve prion-free Holstein bulls were developed through genetic engineering by Hematech Inc., a pharmaceutical research company [a division of Kirin Pharmaceutical] based in Sioux Falls, S.D. .

Three of the animals were slaughtered for testing, and the remaining cattle are now two years old and healthy. A report about the research was published Dec. 31 in the online version of the scientific journal Nature Biotechnology.

“By knocking out the prion protein gene and producing healthy calves, our team has successfully demonstrated that normal cellular prion protein is not necessary for the normal development and survival of cattle,” said James M. Robl, Hematech president. “We anticipate that prion protein-free cows will be useful models to study prion disease processes in both animals and humans.”

… Researchers “knocked out” the prion gene in the transgenic Holsteins, then exposed some of them to the prions associated with BSE, and found the disease didn’t take hold.

Researchers from ARS, Hematech and the University of Texas evaluated the live cattle and conducted post-mortem examinations on slaughtered animals. At least three more years of testing is needed, ARS said.

Abnormal prions are associated with a group of diseases called transmissible spongiform encephalopathies. In cattle, the best-known disease is BSE, also called mad cow disease. In humans, variant Creutzfeldt-Jakob disease is associated with abnormal prions. BSE in cattle and vCJ in humans result in irreversible brain degeneration.

Mutant prions are also associated with scrapie in sheep and chronic wasting disease in elk and deer.

The December 2003 discovery of BSE in a Canadian-born Holstein cow at a Mabton, Wash., dairy caused a media uproar and resulted in the loss of major U.S. export markets, although it appeared to have little impact on domestic consumer beef purchases. Scientists believe that people can contact vCJD from eating beef from BSE-infected cattle. Worldwide, about 180 human deaths have been linked to BSE.

[Peggy Steward: Capital Press]

The new “TC Cow” from Hematech Inc - discussion @ Rancher.net

Oldtimer: “You have to wonder why Hematech scientists, the USDA scientists, many of the major Laboratories and Universities around the world are putting so much effort into developing ways to cure or eradicate BSE and other TSE’s if they are such a miniscule problem as so many on this board would like us to believe they are.”

Kathy: It isn’t about disease control … it is about CONTROL. If you can’t grow your own food, without interference from government, ie: telling you what to grown, when to grown it, how much to grow, then you are not in control, they are … the only relevant change that will result from all this Genetic manipulation … is CONTROL of the cattle business …. It is a sad fact that there is more concerned about BSE than the use of chemical, biological and depleted weapons by our own governments.

Kathy: Nothing like a 2 year old article to help set up some questions. So Hematech started with 150 embryos, and reports on 8. Even Chris Clark of the University of Saskatchewan Western Veterinary College has the ability to read and see that the research is high-lighting the biological importance of the healthy prion protein as a scavenger and neuroprotector.

[Bull Session! @ Ranchers.net]

Scientist questions value of BSE-immune cows

Chris Clark, an infectious disease expert at Western College of Veterinary Medicine in Saskatoon, said it is possible to produce a cow that is immune to BSE but he doesn’t know how useful it would be.

First scientists would have to figure out what the prion protein does and what happens if it disappears.

“I know some of the British research groups are coming to the theory that they think that the prion protein may be important for what they call a scavenger probe,” said Clark.

“What it may do is allow cells to kind of remove the natural waste materials that are produced by cellular metabolism and allow it to be recycled to prevent things accumulating.”

[cbc.com - June 2004]

Potentially Pathogenic Virus Found in Mad Cow Cells

The alternative view that a virus causes spongiform encephalopathies of the brain, such as “mad cow” and Creutzfeldt-Jakob (CJD) disease, rather than prion proteins, which are normally produced throughout life, is bolstered in a new study by Yale School of Medicine researchers.

The report published online January 29 in the Proceedings of the National Academy of Sciences provides evidence that a virus causes these diseases, which are manifested by devastating holes, or sponge-like spaces, in the cerebral cortex. The conclusions counter the now conventional view that abnormally folded prion proteins are infectious, and instead suggests that abnormal prion proteins are late stage footprints left by the virus.

The lead author, Laura Manuelidis, M.D., professor and section chief of neuropathology, infected cell lines with either scrapie or CJD agents …. Manuelidis and her co-authors found an abundance of 25 nm virus-like particles. They also found that the particles did not bind antibodies for the prion protein, indicating they were not composed of prion protein. The development of the particles was independent of pathological changes or neuronal specialization, and preparations with an abundance of these particles correlated with high levels of infectivity, whereas the presence of prion proteins did not.

“… there is a reasonable possibility these are the long sought viral particles that cause transmissible spongiform encephalopathies,” Manuelidis said. “The abnormal protein is probably not infectious, but is a pathological result an infectious virus binding to this host protein. Highly infectious cultures are ideal for fundamental molecular studies of this virus, as well as rapid therapeutic, preventive, and vaccination approaches.”

Co-authors include Zhoa-Xue Yu, Nuria Banquero, and Brian Mullins. The work was supported by a National Institutes of Health grant and by a U.S. Department of Defense grant.

[Yale.edu - February 2007]

Bovine spongiform encephalopathy See Also