Researcher working to perfect CWD test

Correspondent

Watertown, Wis. Don Meyer, president of Rock River Laboratory in
Watertown, may have a test deer hunters have been hoping for since
chronic wasting disease was discovered near Mount Horeb in 2002.
This test may be able to be used to detect mad cow disease,
too.

Meyer, and researchers at Rock River Laboratory, believe they
have discovered a way to screen deer lymph tissue for CWD using a
$45,000 spectrophotometer. This instrument measures how light is
absorbed and reflected by molecules, such as proteins.

Meyer refers to this method as spectra-fingerprinting. He
subjects tissue to infrared light, which is light just beyond red
light in the visible spectrum.

“Diseased and non-diseased tissues have different
spectra-fingerprints,” Meyer said. “I don’t think I’m only
measuring fingerprints from prion molecules, but more likely
detecting differences in molecules due to immune responses. At
least there is evidence of this.”

To execute the test, a trained technician places a piece of
lymph tissue, four millimeters in diameter, on a spectrophotometer
stage and subjects the tissue to infrared light. The data is fed
through to a computer and the amount of light reflected and
absorbed shows up on a computer screen.

This test could be run in less than a minute after the
spectrophotometer has been equilibrated, an initial process taking
several hours. The tests could be done at registration stations,
because the equipment is portable. Meyer estimates the test would
cost less than $10 per sample.

Meyer believes his CWD screening test, which has not yet been
given a name, could replace the current CWD screening test (IDEXX),
which takes several days to run and must be performed in a
laboratory. Tissues that test positive with Meyer’s method could
then go through the lengthy immunohistochemistry test, which is
what Wisconsin has been doing this year with samples testing
positive with the IDEXX screening test.

In other words, all deer samples that test positive have tested
positive twice, once with a screening test, the IDEXX, and once
with IHC.

Any decisions about using Meyer’s test, if it is certified, are
decisions the state of Wisconsin, not Meyer, would make.

Before hunters get overly excited, Meyer’s test has not been
certified and approved by the U.S. Department of Agriculture. There
is good reason to believe it may be, however. When that
certification and approval might be granted is another
question.

“I think his (Meyer’s) technology and applying it to CWD
diagnosis is really promising,” said Julie Langenberg, DNR
veterinary wildlife health specialist. “He’s worked with good
collaborators in USDA and he’s done a lot of work. I’m comfortable
putting it in the promising category, but it has a ways to go. We
want to be supportive of creative approaches like this.”

The DNR has been supportive of Meyer’s work during two hunting
seasons.

Meyer started Rock River Laboratory in 1975 as an agricultural
analysis company, testing soils and feeds. Last year, Rock River
analyzed 80,000 soil samples and 80,000 feed samples.

“TSE Scan is an offshoot of my parent company and TSE Scan is
the company developing this test,” Meyer said. “We had been using
near-infrared analysis for feed analysis since 1983 and it analyzed
protein samples very well.”

Meyer then became more familiar with CWD infection and the prion
protein molecule that is believed to cause CWD in cervids such as
deer and elk.

“In 2002, we approached the DNR and they let us come to the
Veterinary Diagnostic Laboratory in Madison and scan samples during
the summer hunts,” Meyer said. “The near-infrared did not work
well, so we tried another part of the infrared spectrum, the
mid-infrared range. We knew this region of the spectrum can do more
work diagnosing and typifying molecules.”

Meyer went to a USDA laboratory in Pullman, Wash., to discuss
and test his idea and, after calibrating and scanning 50 samples,
his results were perfect.

“The DNR then let us have all the tissues we wanted,” Meyer
said. “We did 88 samples and predicted which would be positive and
which would be negative. Perfect.”

The tissues, Meyer found out, must be either fresh samples or
samples kept in a freezer that is not frost free. Frost-free
freezers dehydrate tissues too much, he believes, and his test does
not work.

With fresh samples, Meyer is optimistic his results will stand
up. If they do, the test could take a giant step to being
certified.

Meyer also tried his test on scrapie (a spongiform
encephalopathy disease in sheep) and was able to predict accurately
which samples were positive and negative.

He then wrote and applied for a patent for the detection of TSEs
(transmissible spongiform encephalopathies) by infrared analysis.
He included mad cow disease in his patient application, but admits
he must go to England to test bovine spongiform encephalopathy (mad
cow disease) samples because there is only one positive sample in
U.S.

This is where he needs help.

“I need some political connections to get approval to go over
and test samples in England,” Meyer said. “This test could have an
immediate and significant impact on Wisconsin farmers. Downer
cattle, for example, that are not sick but have simply slipped on
ice and broken a leg, cannot be slaughtered. If we could set up and
test cattle at a slaughter house, we could tell within a minute if
the cow did or didn’t have mad cow disease.”

Meyer’s test still has to finish certification. He hopes that
could be before Wisconsin’s 2004 deer season.

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