Researchers at the University of Minnesota, working in collaborationwith scientists at the USDA, have used genomic information to developtests that can rapidly detect and differentiate the bacteria thatcauses Johne's disease, a chronic wasting disease found in cattle andother ruminant animals such as sheep, goats and deer. This research,scheduled to be published in the Aug. 30 issue of the Proceedings ofthe National Academy of Sciences, also provides the foundation for abetter understanding of the Johne's disease process and the design ofvaccines to prevent infection.
Johne's disease is devastating to the United States dairy industry,costing about $200 million per year due to reduced milk production.Estimates indicate that the disease is present in approximately 25percent of Minnesota's dairy herds. Because the bacterium that causesJohne's disease, Mycobacterium avium subspecies paratuberculosis, isslow growing in the laboratory, previous tests often took between 6 and18 weeks to process. The current study shows how genomic informationmay be used to develop highly specific, sensitive, and rapid tests forthe detection of infected animals.
These new tests, which enable detection of the bacterium in fecalmatter or milk, can be completed in 72 hours or less with an accuracythat was not possible without knowledge of the complete genome of thebacterium. Since animals shed the bacteria in their milk, fasterdiagnosis will likely help monitor and improve the quality of dairyfoods.
"Since the results of this new test are available much sooner, infectedanimals can be identified and isolated more quickly, thereby providingan opportunity to minimize economic losses to the herd, and breakingthe chain of transmission from animal to animal," said Vivek Kapur,BVSc., Ph.D., principal investigator, faculty member of theUniversity's Medical School and College of Veterinary Medicine, anddirector of the Biomedical Genomics Center. In 2003, Kapur and hiscolleagues at the University of Minnesota were also awarded one of thelargest research grants by the USDA to form a national consortium tostudy Johne's disease in cattle.
Mycobacterium avium subspecies paratuberculosis is also implicated as afactor in Crohn's disease, an inflammatory bowel disease in humans.Infection with this bacterium in humans and all animals is generallybelieved to occur at an early age, with clinical manifestations of thedisease only showing up after several years. In the future, researchersare likely to be able to use this information to work on a test todetect these bacteria in blood or tissue of patients with Crohn'sdisease and ulcerative colitis.
"This research both advances knowledge of the basic science issuessurrounding the disease as well as applies that knowledge for immediatebenefits to animal and potentially human, health," said SagarikaKanjilal, associate professor of medicine, and a co-author of the paper.
Funding for the project was provided in part by grants from the U.S.Department of Agriculture Cooperative State Research, Education, andExtension Service National Research Initiative, and the AgriculturalResearch Service.
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