It’s almost like a secret around the Palouse — not only was the nation’s first case of mad cow disease confirmed in a Washington State cow, but the test used to diagnose it is also produced in the region — in Pullman to be exact.
Long before the holstein on the southeast Washington farm caused an international uproar last December, researchers at Washington State University had been diligently working on ways to better diagnose and understand the devastation caused by transmissible spongiform encephalopathies (TSEs), a group of prion-induced diseases including bovine spongiform encephalopathy — BSE or mad cow disease. A prion is a protein particle similar to a virus.
The breakthrough first came in 1998 when Katherine O’Rourke, a research microbiologist with the U.S. Department of Agriculture’s Agricultural Research Service (ARS), worked with a team of researchers from WSU’s Department of Veterinary Microbiology and Pathology to develop the F-99 monoclonal antibody assay. The assay, which was produced to identify prions in the lymph and nervous tissues of all affected species, was eventually validated and developed into a commercial diagnostic test through the help of Canadian and British laboratories.
“The National Center for Foreign Animal Disease in Winnipeg, Manitoba, operates a BL3 facility with the highest level of biocontainment and has permission to handle the BSE agent,” said Don Knowles, research leader of the Animal Disease Research Unit of ARS and professor in WSU’s College of Veterinary Medicine. “The Canadians were interested in collaborating with us as well as the British, who sent us samples of BSE from the Veterinary Laboratories Agency-Weybridge in the United Kingdom.”
Around this time, VMRD, Inc., a Pullman based veterinary diagnostics company, was on the upswing and decided to license the technology from ARS. Working with researchers from the Agricultural Research Service, VMRD co-developed a practical diagnostic test for TSE/BSE. Scott Adams, VMRD president, began the company literally in his basement in 1980, but it now operates in a spacious new research and production facility just north of Pullman. 0
Internationally, not in U.S.
Made with scrupulous quality control, the TSE prion test kit is among the many that VMRD has developed to help veterinarians diagnose infectious diseases. This test is being sold and used internationally to diagnose BSE or mad cow disease — but not within the United States, according to Adams.
“The USDA doesn’t permit VMRD to sell the test or the F-99 antibody to anyone whose intent is to test bovine tissues of U.S origin — anywhere in the world,” he said. “The only place it is used in America is at the USDA lab in Ames, Iowa, which is where the affected cow from Washington State was first diagnosed. They use the same monoclonal antibody and the same procedure VMRD does,” said Adams.
“The USDA wants to control BSE testing in the U.S.,” he said. “The diagnosis of bovine spongiform encephalopathy is a terribly explosive issue — for the whole cattle industry — as we’ve seen.”
VMRD’s TSE test kit is based on the F-99 monoclonal antibody and was licensed from USDA through the ARS Office of Technology Transfer. This type of test uses an immunohistochemistry method to detect prion proteins in brain and lymph tissue and can only be used for brain samples from dead cattle.
Several years ago, WSU also developed the first and only practical live-animal test for any form of a transmissible spongiform encephalopathy or TSE. O’Rourke, along with Steven Parish and other WSU faculty and researchers in the Washington Animal Disease Diagnostic Laboratory, discovered that prions could be detected in the lymph tissue found in the third eyelid of sheep and some deer and elk, said Knowles.
Sheep have long been known to carry scrapie, a disease similar to BSE, but not believed to be transmissible to humans. Deer and elk throughout the midwest more recently have been infected with another form called chronic wasting disease, which has not shown evidence of transmission to humans to date.
But the third eyelid test does not work for cattle, which primarily harbor the prions in nervous tissues. So, worldwide, the race is in on to find a noninvasive way to measure prions in the blood or other body fluids. Scientists also are searching for any other marker of the disease, such as changes in white blood cells or in blood chemistry profiles, said Knowles.
Keep it in perspective
In other countries, such as Japan, a fast ELISA test is used to screen 100% of beef before it goes into the consumer market. “ELISA tests are fast, but prone to false positives,” said Knowles. “That doesn’t matter too much in a country where there is more prevalence of BSE, but in the U.S., a false positive could hurt public confidence. This is where the highly specific immunohistochemistry tests are invaluable.”
“But keep it in perspective,” he said — agreeing with Adams — “the risk of someone in the United States dying from BSE is highly remote. The risk of dying from influenza, especially this year, is much higher — as are risks from smoking, driving or getting e.coli.”
“In the United Kingdom, with a population of 60 million, there have been about 130 human cases of variant Crutzfeld-Jacob disease (the human form of BSE). With the new controls on cattle feed, there has only been one new clinical case in 2003,” Knowles said. “The devastation of contracting variant Crutzfeld-Jacob is of great magnitude to that one person, so I am not discounting that tragedy, but the risk does need to be held in true perspective.”
Soon after the unfortunate holstein in southeast Washington met its demise, state Sen. Larry Sheahan, R-Spokane, sponsored Senate Joint Memorial Bill 8050, which passed the Senate Feb. 17 and is expected to gain House approval by Feb. 27. The bill asks the federal government for $25 million to build a BL3 animal biocontainment facility at the WSU College of Veterinary Medicine to test for BSE. The memorial also asks for $2 million to continue research into developing a live animal BSE test as well as further work on other food-borne agents, according to Terry McElwain, director of WADDL and the Animal Health Research Center.
Through funding in 2002, the WSU College of Veterinary Medicine became one of 12 accredited laboratories in the National Animal Health Laboratory Network developed through the USDA. These labs are the only state facilities authorized to test for exotic diseases (originating outside of the U.S.) such as foot and mouth disease or avian influenza, said McElwain. But none of these labs has been approved to test for BSE.
“WSU currently does have a BL3 laboratory,” said McElwain, “but we don’t have a BL3 animal facility where we can hold and test live animals. This is what the proposal is for. Having been on steering committees for ironing out concerns on reporting of exotic diseases, I can see no reason why we can’t work through the same issues for BSE as well. It is being strongly recommended to the USDA to change their policy and allow testing in all the states,” he said.
Currently, it takes 5-12 days for a brain sample from a dead cow to be shipped, processed and tested in Ames, Iowa. With construction of a new research and testing facility at WSU, the regional waiting time would be greatly reduced – not only helping the producer but also those consumers standing dubiously in front of the meat counter …wondering.