The appearance of mad cow disease, or bovine spongiform encephalopathy, in the US Dec. 23 has presented a potential opportunity for proteomics companies — especially those that are already working on diagnostics for the disease.
BSE, which is caused by a central nervous system infection with abnormal proteins called prions, has been recognized in the European Union for nearly two decades. But the US is the leading beef-producing country in the world — being responsible for 25 percent of the world’s beef supply according to one 2002 estimate, and 16.5 percent of its exports — compared to the EU, which produces 15 percent of the world’s beef supply and 7.5 percent of exports.
And when a UK-based reference lab on Dec. 25 confirmed the Dec. 23 preliminary diagnosis of the presence of BSE in a cow butchered Dec. 9 in a Washington State slaughterhouse, over 24 countries reacted by suspending the importing of US beef.
The disease, which is believed to enter the bovine population when cattle ingest sheep or other cattle infected with abnormal prions, is of particular concern because it has been shown to spread to humans in rare cases, causing a fatal neurodegenerative disorder called variant Creutzfeldt-Jakob disease.
Long before the Dec. 23 announcement of BSE’s arrival in North America, proteomics companies on both sides of the Atlantic, including SomaLogic of Boulder, Colo., and Proteome Sciences of Surrey, UK, have been involved in projects to develop diagnostic tests with their particular technologies.
“This is a very exciting field — it’s exciting to anyone who has a tool that can work in this arena,” said Helen Petach, senior director of scientific affairs at SomaLogic. “It’s certainly not something that you would want to ignore at this point.”
For proteomics companies entering the field, however, the bar is already high. Prionics, of Schlieren, Switzerland, claims 50 percent of the worldwide market for BSE testing procedures with its antibody reagent kit — which it says has scored 100 percent sensitivity and specificity in evaluation tests — while Bio-Rad Laboratories says its test is the most widely used screening kit in the world, and was chosen as the exclusive supplier of BSE diagnostic tests to the UK. A whole host of other companies have also joined in (One website lists 46 companies doing some sort of work in the prion diagnostic area).
But SomaLogic has had the idea for some time that it can offer something new with its photoaptamers, single-stranded DNA and RNA molecules that take on three-dimensional shapes and specifically bind target molecules.
“Photoaptamers are highly specific to their target protein and they tend to measure conformational changes or conformations of the protein, not linear sequence,” explained Petach. “As a result, because mad cow is caused by a conformational change in the protein, photoaptamers are well-positioned to measure the two different conformations of the protein.”
Ordinarily, the company uses an array of photoaptamers to query a sample for large numbers of proteins at once. Each photoaptamer is bound to a surface to capture the protein of interest, then non-covalently-bound proteins are washed away, leaving only the proteins of interest. In the case of BSE, however, SomaLogic is currently working only with capturing the single BSE protein. Petach indicated that an array was in the works for the future, however, should proteins other than the single abnormal prion protein become relevant for detecting BSE.
Last January, SomaLogic entered into a research collaboration with animal health giant Merial to incorporate photoaptamers into diagnostics for BSE. Petach would not say when a product from the collaboration will be launched, but did say that a diagnostic for cattle would be the “initial focus” of a product.
Another company, Proteome Sciences, has identified an Apo-E lipoprotein as a diagnostic biomarker for BSE. It licensed out the biomarker to Idexx Laboratories of Westbook, Maine last April. Under the deal, Idexx received exclusive global rights to develop and commercialize diagnostic assays for the detection of BSE in cattle and of TSE in other animals.
While the current tests, such as Prionics’ kit, all require samples to be taken from post-mortem brain tissue, the Idexx-Proteome Sciences diagnostic is designed as a blood test to be used on live animals.
Under the collaboration, Proteome Sciences said last April that it would receive upfront and milestone payments as well as royalties on sales of products using the biomarker.
As of press time, Proteome Sciences was unavailable to comment for this article on the progress of this collaboration. Elisabeth Perry, manager of corporate communications at Idexx, said only, “At this time there really are no significant developments that we’re at liberty to discuss with you."
Proteome Sciences is also involved in a different end of the BSE sector. Pursuing its traditional strategy of collaboration with academics (see PM 09-09-02), the company signed a deal in late November to work with the UK’s Medical Research Council to identify differential protein expression in patients with CJD and variant CJD.
While variant CJD is contracted through consumption of BSE-infected beef, other forms of CJD can be hereditary — mutations in genes cause a person to produce abnormal prions — or contracted through means other than through consumption of infected beef. To measure the extent of the mad cow problem in humans, it is necessary to distinguish different forms of the disease
In the MRC collaboration, Proteome Sciences is taking samples from age and sex matched patients with the diseases, and will undertake protein separation, identification, and characterization to search for biomarkers for new diagnostics, prognostics, and therapeutics.
The idea of protein biomarker patterns for CJD, or even for BSE in serum, could also be of potential interest to SomaLogic, Petach said. “Typically, we would use [our] arrays to go after a suite of markers [for] a protein signature for a disease, so if that signature were available in, say, BSE, that would be another approach,” she said. The obvious benefit of going after a signature would be the possibility of testing for the disease in living animals, as Proteome Sciences’ test aims to do.
But such a test, she said, would be a much longer-term project. For the moment, the company is focusing on the low hanging fruit of the BSE prion. “You already know what the BSE infectious agent is, so if you develop a diagnostic and measure that infectious agent, you’re done,” Petach said.