On Track to Prevent Johne's Disease with a Drug or Vaccine

MADISON, WI - 10/9/06 - To date, the only cure for Johne's disease, a debilitatingwasting disease in dairy cattle, has been to eliminate affected cows from theherd. But researchers at the University of Wisconsin-Madison (UW) School of VeterinaryMedicine are closing in on a way to cull the disease-causing bacteria instead.

The aim is to stop Johne's in its tracks through the development of a vaccineor drug. Work can begin as soon as funding is found.

Dr. Adel M. Talaat, a microbiologist at UW's School of Veterinary Medicine,has put a genomics-based technology to work to study thousands of genes fromJohne's-causing bacteria. From an initial pool of 5,000 genes, he screenedout a library of 1,500 mutants that possessed unique factors, meaning they hadpotential for being targets that could be used to stop bacteria.

The key is to determine which virulence factors are actually important.

“The bacteria really need certain components to survive,” Talaatexplains. “By identifying exactly what they need, we can then attempt todevelop a way to disarm the target antigens, so that they can't succeedat infiltrating the host.”

Further tests narrowed down the 1,500 genes to 25 that seemed important. Elevenof those were tested in mice, from which they found seven potential virulencefactors.

“Those are the virulence factors that we either remove from the organismso it can't infect the host, or develop a vaccine from them so the hostcan develop its own defense mechanism,” Talaat says. The Wisconsin AlumniResearch Foundation (WARF) has filed a patent application for his process andis currently funding part of his research to test new vaccines.

Talaat hopes to obtain funding from USDA to support additional studies in largeanimal models, which are much more expensive than testing in mice. His initialresearch was funded by the Animal Formula Fund of the Wisconsin AgriculturalStation.