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Washington Scientist Honored by USDA Agency / February 13, 2002 / News from the USDA Agricultural Research Service

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National news release

Donald Knowles



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Washington Scientist Honored by USDA Agency

By Jan Suszkiw
February 13, 2002

BELTSVILLE, Md., Feb. 13—Medical veterinary officer Donald P. Knowles has been named “Distinguished Senior Research Scientist of the Year" by the Agricultural Research Service for scientific leadership in developing methods to diagnose costly animal diseases. ARS is the U.S. Department of Agriculture’s chief scientific research agency.

Knowles, who earned his Ph.D. from Washington State University in 1988, heads the ARS’ Animal Disease Research Unit in Pullman, Wash.

He and 15 other ARS scientists will receive plaques and cash awards for their scientific excellence during a recognition ceremony Feb. 13 at the agency’s Henry A. Wallace Beltsville Agricultural Research Center.

“Dr. Knowles has been the driving force behind research leading to new diagnostic tools with which we can more accurately detect infections with disease agents such as Anaplasma marginale in cattle, and prions associated with scrapie in sheep,” said Edward B. Knipling, acting administrator of ARS.

Anaplasmosis is a tickborne disease caused by a parasite that infects and destroys the red blood cells of an animal host in which it’s transmitted. Anaplasmosis is estimated to be responsible for between 50,000 to 100,000 cattle deaths per year. Persistent infections that don’t kill the animals can lead to poor weight gain, weakness and other complications. Cattle that survive the initial infection become life-long carriers capable of transmitting the parasite to other cattle.

At the ARS Pullman lab, Knowles led a team in investigating cattle immune responses to the parasite that resulted in a new diagnostic test that has proved more accurate than the standard method, called complement fixation (CF) test.

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Though it’s been used to check cattle prior to interstate or international transport–such as from North America to Canada–the CF tests has two main drawbacks. One is that it relies on the use of live animals to obtain antigens. In this case, it is surface proteins on the parasite that trigger antibodies in the animal’s blood. The second drawback to using the CF tests is that they can yield misleading results, such as “false negatives,” which allow the movement of cattle capable of transmitting the disease.

Knowles’ lab, along with WSU collaborators, overcame the problem by isolating and cloning one of these surface proteins, and then developing a competitive inhibition ELISA test to check for natural antibodies that bind to the antigen in blood samples from cattle. ELISA stands for enzyme linked immunosorbent assay.

In collaboration with ARS, the Canadian Food Inspection Agency (CFIA) used the new anaplasmosis test to diagnosis infections in cattle as well as bison. USDA’s Animal and Plant Health Inspection Service is also collaborating with ARS on using the test to survey cattle in tick-infested areas of the United States. Knowles’ lab, meanwhile, is working with WSU scientists to develop new vaccines using information on the sequence of the Anaplasma marginale genome.

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Other accomplishments that Knowles will be recognized for at the Feb. 13 awards ceremony include:

Leadership in developing diagnostic tests for several other agriculturally important animal diseases, including equine babesiosis (piroplasmosis) in horses, small ruminant lentiviruses in sheep and goats, transmissible spongiform encephalopathy (scrapie) in sheep, and bovine spongiform encephalopathy in cattle.

Expediting collaboration with CFIA, APHIS, the National Centre for Foreign Animal Disease in Winnipeg, Canada, and companies involved in diagnostic kit development and distribution.

Contributing as senior inventor or co-inventor on five patents. The most recent, filed December 2000, covers the use of monoclonal antibodies to detect infectious agents called prions believed to cause the neurological disease scrapie in sheep.

Providing guidance to six graduate students investigating these animal diseases in pursuit of their M.S. or Ph.D. degrees.

Knowles is the author or co-author on 18 book chapters and 63 scientific papers. He is a member of five professional organizations, including the American Association of Veterinary Laboratory Diagnosticians. He earned a B.S degree in agricultural science in 1978 and a B.S. degree in veterinary science in 1980 at the University of Illinois, and a D.V.M. (Doctor of Veterinary Medicine) there in 1982. He joined the ARS lab at Pullman in 1986 and earned his Ph.D. at Washington State University in 1988.

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Last Modified: 2/13/2002
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