Candidate vaccine for Johne’s Disease developed at UW-Madison

A candidate vaccine for paratuberculosis, a dangerous infection affecting Wisconsin agriculture, has been developed by scientists at UW-Madison.

Also known as Johne’s Disease, paratuberculosis can be found in thousands of animals in Wisconsin.

Each year, DATCP distributes over 180,000 tests for the disease. In 2016, the agency had 4,905 positive tests, 133,349 negative tests and 1,371 “suspect” cases.

Raechelle Cline, a spokesperson for DATCP, said those uncertain cases are quite common, and that false positives can also occur.

All in all, 1,825 herds were tested and 149 herds were officially declared to have the infection.

But Johne’s Disease isn’t just a Wisconsin phenomenon.

According to the USDA’s Animal and Plant Health Inspection Service, about 68 percent of U.S. dairy operations were found in 2007 to be infected with the microorganism causing Johne’s Disease: a Mycobacterial avium subspecies called M. paratuberculosis, or MAP.

More recent national surveys put that number around 66 percent, according to Cline, who added that Wisconsin dairy operations’ surveyed rate is closer to 57 percent.

Cattle afflicted by MAP often have digestion and milk production issues, and can also experience fever, infertility, weight loss and swelling under the jaw. And DATCP warns that for every animal showing symptoms, there may be up to 25 others infected.

“It causes diarrhea in animals,” explained Adel Talaat, a professor in the department of animal health and biomedical sciences at UW-Madison. “They suffer, they are not eating well — not producing enough milk. In severe enough cases, the animal will eventually die.”

Talaat led the team working on this vaccine, and sees paratuberculosis as a major issue for the state. He was hired by UW-Madison in 2002, and soon after began to look into how the effects of the disease could be mitigated.

“I was thinking about how to help the state where I live, how to help the local economy,” Talaat told Coming from a background in bacteriology, his research involves “thinking about ways to better understand disease, to see how we can control it.”

Talaat and his team have developed mutated MAP strains that are non-virulent, which can be introduced into an animal’s body to confer immunity.

Other paratuberculosis vaccines currently exist, but are not very widely used, according to Talaat. That’s because they can’t do much to halt more severe infections, and fail to prevent transmission of the infection through feces — a major issue for the state.

The DATCP says MAP can survive up to 9 months in manure pits, 11 months in soil and 17 months in water.​

“Our vaccine definitely deals with these concerns,” he said. “Once you get the new vaccine, you can’t spread the bacteria — you can’t pass it on.”

Talaat and his team are still in the process of testing their vaccine, with the eventual goal of commercializing it so it can be available “in Wisconsin and worldwide.”

–By Alex Moe