Bovine spongiform encephalopathy, also called mad cow disease, is a genetic disease as well as a foodborne disease, according to new research from Kansas State University.
Juergen A. Richt, Regents Distinguished Professor of Diagnostic Medicine and Pathobiology at K-State’s College of Veterinary Medicine, says BSE has long been thought to be caused by ingesting food contaminated with the disease.
"We now know it's also in the genes of cattle," says Richt. "Our findings that there is a genetic component to BSE are significant because they tell you we can have this disease everywhere in the world, even in so-called BSE-free countries.”
His team's new findings show that BSE is also caused by a genetic mutation within a gene called Prion Protein Gene. Prion proteins are proteins expressed abundantly in the brain and immune cells of mammals.
Richt says the upside of knowing that BSE has a genetic component is that it offers ways of stamping out the disease through selective breeding and culling of genetically affected animals. Therefore, Richt and his colleagues developed high throughput assays to offer the possibility for genetic surveillance of cattle for this rare pathogenic mutation.
"Genetic BSE we can combat," Richt says. "We have submitted a patent for a test system that can assess all bulls and cows before they're bred to see whether they have this mutation."
In studying the brain of a 10-year-old cow from Alabama with an atypical form of BSE, researchers found the same type of prior protein gene mutation that is found in human patients with the genetic form of Cruetuzfeldt-Jakob disease, also called genetic CJD.
Besides having a genetic origin, other human forms of prion diseases can be sporadic, as well as foodborne. The food-borne form of Creutzfeldt-Jakob disease is called variant CJD.
An article by Richt and colleague Mark Hall of the National Veterinary Services Laboratories in Ames, Iowa, was published online in the journal PLoS Pathogens. Richt conducted the research while working at the National Animal Disease Center operated in Ames, Iowa, by the U.S. Department of Agriculture's Agricultural Research Service.
Richt says that prion diseases including BSE are referred to as "slow diseases."
"It's a slow process for infectious prion proteins to develop," he says. "That's why the disease takes a long time - as long as several years - to show up."
Richt says BSE caused by genetics is extremely rare. A recent epidemiological study estimated that the mutation affects less than 1 in 2,000 cattle. The study was done in collaboration with the U.S. Department of Agriculture's U.S. Meat Animal Research Center in Clay Center, Neb., which is operated by the Agricultural Research Service.
Richt is one of more than 150 people at K-State actively involved animal health and food safety research. He has authored or co-authored more than 80 peer-reviewed articles and recently was named to the scientific advisory board for the Scientific and Technical Review of the World Organization for Animal Health, the OIE in Paris.