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University of Wyoming Research Targets Western Wyoming Brucellosis Problem

 

News from
University of Wyoming

By Robert Waggener, U of W Staff
January 4, 2005

Playing heavy metal, bluegrass, classical or country music is one way University of Wyoming researcher Gerry Andrews takes the edge off when performing painstaking laboratory work on brucellosis.

If he is in tune, the College of Agriculture assistant professor and his team could discover a new vaccine to help control the deadly disease in cattle, elk and bison.

“It’s a good thing I meditate,” Andrews said jokingly as he carefully inserted a pipette into a gel containing a genomic DNA preparation of Brucella abortus, the bacterium that can cause elk, bison and domestic cattle to abort their offspring. The disease is prevalent in western Wyoming and consequently has become a major agricultural and wildlife concern.

A national effort to eradicate brucellosis in the United States was launched in the 1930s, and Wyoming was declared free of the disease in 1985. The state lost that status in 2004 when a herd of cattle near Pinedale became infected, probably after contact with infected elk from the nearby Muddy Creek feed ground, according to a report by the Wyoming Brucellosis Coordination Team, which formed in 2004 to identify issues relating to the disease and develop recommendations for control.

“If brucellosis gets into a completely naïve cattle herd (one that hasn’t been exposed to the disease before), you will see an abortion storm, and that’s what we saw with the Sublette County herd,” said Donal O’Toole, director of the Wyoming State Veterinary Laboratory and head of the Department of Veterinary Sciences, which is conducting several brucellosis-related research projects. “That herd and two others that later tested positive were depopulated. Those guys were basically knocked out of business.”

Brucellosis has received plenty of attention in Wyoming and the region, but many residents don’t know if it’s truly a problem or has just become a political issue between policymakers, ranchers, hunters and environmentalists.

“It’s definitely a problem to the cattle industry just in terms of the amount of testing the cattle now have to go through,” O’Toole said. Livestock can’t change hands until test results come back, and that’s slowing down ranch operations.

To O’Toole’s knowledge, no one has completed an accurate estimate of what this costs the state, although he estimates it is several million dollars annually in testing, surveillance and research on the state and federal levels.

“Looking at our operation alone, brucellosis testing at the state vet lab has gone from 46,000 samples per year to about 160,000. We’ve had to hire two new technicians to keep up.”

O’Toole said Wyoming will seek to regain brucellosis-free status this winter. Its application in December was forwarded to the U.S. Department of Agriculture, which will assemble a team of brucellosis experts to determine if control efforts are adequate. Even if the status is granted, O’Toole predicted, the state will continue to face challenges.

“All other states know is we have a wildlife reservoir of a disease that spills over periodically into cattle,” he said in reference to the Greater Yellowstone Area. “So when we’re selling cattle, even when we have our status back, the other states will likely have additional requirements on Wyoming, so the costs will still be there.”

More important, O’Toole emphasized, getting brucellosis-free status back does nothing to lick the brucellosis problem, and that’s where UW researchers come in. They are tackling issues of vaccine development, delivery methods and how to better diagnose the disease.

College of Agriculture Dean Frank Galey said politics have influenced brucellosis-related decisions by state lawmakers, but science is the top priority at the ag college and state vet lab.

“Our researchers are trying to find scientific answers for the policymakers. We have projects going on right now looking at the revaccination of cattle, we have diagnostic test development underway, and we have one faculty member who is very interested in vaccine development,” Galey said.

“The problem of brucellosis is a long way from being solved because it’s so complex, but I think if we take this one bite at a time, we can make some progress,” he added.

Before a new vaccine is discovered, Andrews and his research team must first better understand the genes involved in Brucella virulence, the capacity of a microorganism to cause disease.

“To build a better vaccine, you really need to have a better understanding of the pathogens that cause a disease. With Brucella abortus, there is some knowledge out there of how the pathogen causes disease, but there is still much to learn,” said Andrews, who is confident his team will discover new genes involved in the virulence. All of their efforts are now going into preliminary work.

On this particular day, Andrews is attempting to isolate genes from a vaccine strain of Brucella abortus. He is being observed by two undergraduate microbiology seniors taking an investigations course, Heidi Blittersdorf of Laramie and Caitlin Gade of Sundance. “Heidi, did you run a gel of that last DNA prep? How does it look?” Andrews asked.

“Beautiful,” Blittersdorf responded, matter-of-factly.

It’s obvious Andrews is enthused about his work, even the tedious preliminary experiments necessary to find a new vaccine. “This background work is all part of science and, fortunately, I love it,” the Department of Veterinary Sciences researcher said.

Other principal team members are Assistant Professor Larry Goodridge of the Department of Animal Science and William “Hank” Edwards, a Wyoming Game and Fish Department wildlife disease specialist stationed on the UW campus.

In another brucellosis project, veterinary sciences’ Associate Professor Don Montgomery is researching the effectiveness of the vaccine RB51 on cows. The vaccine is now administered to calves to help prevent the disease, and Montgomery and Steve Olsen of the USDA’s Agricultural Research Service in Ames, Iowa, are studying whether it will work in adult cattle.

“We want to know if you vaccinate adult cows with RB51, does it have any adverse effects on the cows or their fetuses,” Montgomery said. “If they do abort, was the vaccine responsible? More importantly, does it give those cattle an advantage to ward off Brucella abortus infection?”

O’Toole supports the idea of focusing on vaccinating cattle in areas where brucellosis is a problem instead of spending resources on wild animals.

“That makes sense to me because the number of cattle herds that are exposed is pretty small, and you can easily get to the cattle,” O’Toole said.

“If you have a perimeter of solidly vaccinated herds all around the Greater Yellowstone Area, that would be very advantageous; but the current vaccine (RB51) only gives 70-percent protection in cattle as administered to calves. If we had a vaccine that was as good as the rabies vaccine, which approaches 100-percent protection, I wouldn’t say the problem is solved, but that would be a huge shot in the arm.”

In an ambitious project launched last fall, researchers in the College of Agriculture are trying to develop better methods to identify infected elk that represent the highest risk to cattle and other elk. The team also wants to find better diagnostic and research tools to identify strains of brucellosis circulating among elk.

An additional goal is to improve data about elk brucellosis incidence, correlation of seroprevalence (the frequency of individuals in a population having a particular element in their blood serum) with infection, and impacts of habitat improvement on dispersal of elk during Wyoming’s harsh winter months.

In October, the research team received a $311,000 grant from the USDA’s Cooperative State Research, Education, and Extension Service to help fund the work.

Principal faculty members involved are Andrews, Goodridge, and Professor Ken Mills and Associate Professor Todd Cornish, both of the Department of Veterinary Sciences. They will collaborate with the G&F, including Edwards and Jared Rogerson, a brucellosis feed ground habitat biologist in Pinedale.

Four graduate students are assigned to the project: Heather Sanchez of Albin, Laura Linn of Wilson, Amanda Fluegel of Dakota, Ill., and Mandy Kauffman of Traverse City, Mich.

“I am very excited about the project,” Kauffman said. “I am from Michigan, where we face an interesting management situation with bovine tuberculosis in our white-tailed deer. I think brucellosis poses a similar situation in Wyoming, and I am looking forward to hopefully being a part of developing better ways to deal with the disease.”

O’Toole noted: “This is the biggest thing our department has ever bitten off, and there will be a lot of people watching.”

Brucellosis research is not without controversy, as attested by a five-year test-and-cull project that began last fall on a western Wyoming feed ground.

“It is basically a large experiment the G&F has committed to; it wants to determine if the percentage of infected animals goes down if test-positive animals are removed from the herd. It involves running elk through chutes, holding them for testing, and literally sending some of them to slaughter if they are positive,” O’Toole said.

“We know this works for cattle because this is how it was done to eradicate brucellosis in the United States, but this kind of a study has never been done before in elk,” added O’Toole, whose department will help the G&F document cases.

“A lot of folks on the environmental side are not happy with this kind of hands-on management with a wild animal because they see brucellosis as a problem with cattle, not elk,” O’Toole continued. “Some people feel pretty uncomfortable when you see large numbers of free-ranging elk held in corrals. That’s not how we want to think of the animals. We want to think of elk roaming free on spruce- and aspen-covered mountain sides.”

On the agricultural side, O’Toole said, concerns of ranchers whose operations border G&F feed grounds are as valid as those raised by environmentalists. The elk are being unnaturally concentrated at exactly the time when transmission of the disease usually occurs, and that’s late winter and early spring during the calving season. Cattle, elk and bison are attracted to newborns, and this curiosity can lead to a fatal attraction when a newborn happens to be an infected fetus that was aborted.

Why not close the feed grounds? This would force the elk to disperse, and studies have already shown that brucellosis is self-limiting in free-ranging elk. This was the most contentious topic addressed during meetings of the Wyoming Brucellosis Coordination Team. The team consists of 19 members including Mills and Galey, who was appointed chair by Gov. Dave Freudenthal. There are also 10 technical advisers including O’Toole and William Gern, UW’s vice president for research. Ranchers, hunters, G&F personnel, veterinarians, politicians and state and federal officials are also on the committee.

Discussions eventually turned to the issue of closing feed grounds, which proved to be the 800-pound gorilla in the closet, according to the group’s 37-page report delivered in early 2005 to the governor and legislature. From a purely veterinary or scientific perspective, closure of the grounds makes sense; however, the report indicates social, economic and political factors won out.

The G&F estimates the elimination of winter feeding would result in an elk mortality of between 40 and 80 percent in western Wyoming because of the loss of natural habitat. Sportsmen would have fewer opportunities, and businesses that depend on hunting would have a tougher time making ends meet. Few would stand for watching elk starve to death. Another argument for maintaining the grounds is the ability to cull infected elk and administer vaccines to entire herds.

The efficacy of vaccines now available (RB51 and Strain 19) is marginal in elk, and Andrews and his team are working to change that; but they, too, face political roadblocks. After 9/11, the federal government listed Brucella abortus as a potential bioterrorist agent, or Select Agent. This listing effectively halted research on brucellosis in large animals.

“Let’s say Gerry comes up with a good candidate vaccine,” O’Toole said. “The only way to prove that it works is to put the thing into elk and challenge them a couple of weeks later with a known virulence strain of Brucella abortus and see if they resist infection. That is the meat in the sandwich, but we’re pretty darned constrained at the moment because we can’t do any vaccine challenge studies.”

O’Toole said he hopes the government comes up with a common-sense solution that will enable laboratories to resume using Brucella abortus in large animals in outdoor settings – and soon. “They could easily require a $10 to $20 million outdoor facility equipped with multiple electric fences, reinforced concrete and acres of buffer zones – something like the German POW camps in World War II. That would be absurdly expensive and ridiculously restrictive, and no one would pay for it.”

Assuming the restrictions are softened and the Andrews team proceeds, heavy metal music and all, what kind of chance does it have in developing an effective vaccine? “It’s kind of a shot in the dark, but Gerry and his colleagues have a fairly high level of confidence in this,” O’Toole said. “It’s a cliché, but the only way never to fail is to never try.”