Prion diseases such as mad cow disease or Bovine Spongiform Encephalopathy (BSE) are caused when normal proteins adopt an adverse conformational state. The protein sequence is the same as a normal protein; it has just adopted a conformation that causes it to aggregate or do other bad things. These diseases are transmissible because the protein is capable of inducing that conformation state in other normal proteins. If you get a little bit of the bad protein, it can make all of your proteins go bad as well. (It is so sad when good proteins start running with a bad crowd.)
These diseases are really difficult to get rid of because you have to get rid of all the badly conformed proteins, and any molecular biologist will tell you that actually destroying protein often takes a little more than a smile — particularly if it is in an animal at the time. They are resistant to most sterilizing agents because the diseases are not alive in the strictest sense of the term.
However, is the normal protein from which the disease is derived even necessary for the animal? Numerous genes are knocked out in mice everyday, and in many cases these have little or no side-effects for the animal. If we could knockout the gene that produces the normal protein, the animal would be immune or resistant to the formation of the disease — because the aberrant protein would have nothing to change in the new host.
Researchers at the Department of Agriculture have done just this, and they have shown that cows lacking this gene do just fine:
The U.S. Department of Agriculture’s Agricultural Research Service (ARS) have announced initial results of a research project involving prion-free cattle. ARS scientists evaluated cattle that have been genetically modified so they do not produce prions, and determined that there were no observable adverse effects on the animals’ health.
“These cattle can help in the exploration and improved understanding of how prions function and cause disease, especially with relation to bovine spongiform encephalopathy, or BSE,” said Edward B. Knipling, administrator of ARS. “In particular, cattle lacking the gene that produces prions can help scientists test the resistance to prion propagation, not only in the laboratory, but in live animals as well.”
Prions are proteins that are naturally produced in animals. An abnormal form of prion is believed to cause devastating illnesses called transmissible spongiform encephalopathies (TSEs), the best known of which is BSE.
ARS studied eight Holstein males that were developed by Hematech Inc., a pharmaceutical research company based in Sioux Falls, S.D. The evaluation of the prion-free cattle was led by veterinary medical officer Juergen Richt of ARS’ National Animal Disease Center (NADC) in Ames, Iowa. The evaluation revealed no apparent developmental abnormalities in the prion-free cattle.
While these animals are in essence genetically-modified, I would also add that there is no chance of anyone have side-effects from eating them. In this case, the researchers took out a gene that was in the animal before, but they didn’t add anything in its place. I think that the arguments against GM foods are pretty ridiculous, but even those arguments don’t apply for this animal.
Looks like a big step in stopping the spread of BSE.