WSU research team tackles dairy disease

A Washington State University team is battling Johne ’s (pronounced YO-knees) disease, also known as paratuberculosis, a multibillion-dollar problem in the dairy industry worldwide.

Paratuberculosis is a chronic, contagious bowel inflammation that causes persistent and progressive diarrhea, weight loss, debilitation and eventually death. It affects cattle, sheep, goats, llamas, camels, farmed deer and other domestic, exotic and wild animals with multiple stomachs. It has also been recognized in wild rabbits.

An estimated 22 percent of all U.S. dairy herds are infected with Johne’s disease, although most other countries have much higher infection rates.  This expanded research effort is being funded as part of a $4.4 million grant from the U.S. Department of Agriculture.

WSU will receive about $200,000 per year for three years for the research, most of which will be based in the College of Veterinary Medicine.  The veterinary college will hire at least one research associate to help conduct the studies.

Bill Davis, a professor in WSU’s Department of Veterinary Microbiology and Pathology, has been named the lead immunologist for the Johne’s Disease Integrated Program. Joining him on the WSU portion of the research team are George Barrington, Wendy Brown, John Dahl, Chris Davies and John Gay.

A micro-organism called a mycobacterium causes paratuberculosis.  It is resistant to control measures. It can survive on pasture for more than a year, but sunlight, alkaline soils and drying reduces its survival rate. The organism is shed in large numbers in feces of infected animals.  Infections result when contaminated feed and water are consumed.

Davis developed the essential laboratory reagents required to study a cow’s immune response to the infectious agent. The work is a vital step in the development of a vaccine.

“For more than 20 years, I’ve worked to develop the reagents needed for studying this important disease,” said Davis, who also served on the National Academy of Sciences Johne’s Disease Committee.  “You might say it has been somewhat of a singular vision for all this time.”

Davis and his fellow researchers will analyze the “memory” of a key immune cell as it reacts to exposure to different parts of the micro-organism.

“The hope is to be able to identify genes in the disease agent that trigger it to go into survival mode during times of environmental stress,” explained Davis.  “After that, we will look to develop a so-called ‘knock-out strain’ that lacks this gene or genes rendering the agent more susceptible to destruction and control.  At the very least, we look to develop a vaccine based on the knock-out strain that can prevent shedding of the organism.”

The disease has a relatively slow onset after exposure making it very difficult to control as animals move into herds. Infected animals that are carrying the disease but have not shown symptoms usually introduce the disease into a clean herd.

The USDA’s Cooperative State Research, Education, and Extension Service, the department’s leading research and education funding agency, provided funding for the WSU research.

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