Ohio State kicks prion test effort into high gear

WOOSTER, Ohio – Ohio State University researcher Srinand Sreevatsan is looking for a way to identify BSE-causing prions through clinical samples such as blood, before the onset of symptoms.

Live animal test. Sreevatsan is searching for a fast and reliable test for the diagnosis of transmissible spongiform encephalopathies (TSEs) in live animals.

He works at the Ohio Agricultural Research and Development Center’s (OARDC) Wooster campus.

Defense grant. Funded by a three-year U.S. Department of Defense grant, Sreevatsan is developing a test to detect prions – the agents responsible for bovine spongiform encephalopathy (BSE, commonly known as mad cow disease).

The test would also uncover other TSEs such as scrapie in sheep and goats, chronic wasting disease (CWD) in deer and elk, and Creutzfeldt-Jakob disease (CJD) in humans.

Currently, definite diagnosis of TSEs is only possible after death.

In the case of mad cow disease, it takes anywhere from two to eight years for a cow to show symptoms of infection.

Detecting prions. The abnormal form (PrPsc) of a normal host protein (PrP), prions are found mainly in the brains and spinal cords of infected animals and humans.

“The idea is to detect the prion protein, which is folded abnormally as compared to its normal counterpart, in an animal that’s still living, using non-invasive approaches,” Sreevatsan explained.

Focus on scrapie. To develop his test, Sreevatsan is using scrapie as a model, since the disease is present in Ohio.

And unlike other researchers working on the development of prion-detection tests, he’s using high-affinity nucleic acid ligands – molecules that have shown the ability to bind to and differentiate between different proteins – instead of antibodies.

“Antibodies so far have not shown promise toward differentiating different isoforms of the prion protein,” Sreevatsan said.

Moving forward. Sreevatsan has already identified several ligand candidates. Now he’s trying to define the physical and chemical characteristics of the binding, and whether this binding is optimal for detecting very low quantities of the prion protein.

That’s key to developing a test reliable enough to allow health and agriculture authorities to adequately survey for TSEs.

OARDC is the research arm of Ohio State’s College of Food, Agricultural, and Environmental Sciences.