Hunters and wildlife managers eager to hear the promise of a vaccine to rid North America's deer and elk herds of chronic wasting disease (CWD) were met with a shot of reality at a recent Wisconsin Department of Natural Resources (WI DNR) meeting, reports the Wildlife Management Institute. Following weeks of public speculation, researchers and managers from the Canadian Pan-Provincial Vaccine Enterprise (PREVENT) and Vaccine and Infectious Disease Organization and International Vaccine Center (VIDO-InterVac) traveled to the WI DNR headquarters in order to clear up rumors on the nature and status of their CWD research.

"Clearly, we don't have a vaccine that's ready to go out into animals yet," said Dr. Scott Napper, a biochemist at the University of Saskatchewan and Program Manager of Emerging Diseases at VIDO-InterVac. For the past five years, Napper and his team have been working on developing a vaccine-based technology aimed at treating prion diseases such as CWD. This technology takes advantage of the fact that the abnormally formed proteins (or prions) responsible for diseases like CWD, scrapie or mad cow disease possess unique characteristics that can be targeted by a vaccine.

While the theory is sound, and early test results show potential, bridging the gap between the theory and practical application as a CWD vaccine will require more than a little time and financing. "We don't underestimate the complexity of the problem here," said Napper.

A significant piece of that problem has been public reaction to the research. Although the research effort was initially announced in a March 2010 press release published by VIDO-InterVac's partner PREVENT, only recently have sportsmen's forums and chatrooms been abuzz with reports of a "miracle drug" that will make current CWD management programs obsolete. Unfortunately, nothing could be farther from the truth.

"This is not a magic bullet," said Napper. "But if it works as well as early tests indicate, it will go a long way to reducing the number of infected animals."

Following a series of successful proof-of-concept studies in genetically modified mice, Napper's research caught the attention of PREVENT. Federally funded and charged with "creating a pipeline linking the research institutions with the private sector and non-governmental partners for the benefit of all Canadians," PREVENT currently is working toward producing an injectable form of the vaccine that, if all goes well, could be commercially available in two years.

Although impractical for wild deer and elk, the injectable vaccine may prove beneficial for captive animals. Researchers admit, however, that the vaccine's effectiveness in deer or elk is not yet known. Neither is it known what the ultimate result of the research will be. "Is the goal the absolute protection of the animals, or will it be simply to reduce the amount of infectious material produced and released from the animal?" posed Napper. As of yet, no one has the answer.

But that question has many CWD biologists and managers cautious about the potential use of this technology in wild deer and elk populations. Since CWD prions are shed by infected animals into the environment and onto other animals, the only sure way to stop disease transmission is by eliminating the prions. If a future vaccine only reduces "the amount of infectious material produced and released from the animal," biologists are worried that infected animals might live longer and continue to shed prions beyond the normal lifespan of the disease. ?

Unfortunately, speculation is the closest biologists have to answers. Even more uncertain is the future development of an oral form of the vaccine PREVENT plans to produce along with the injectable version. This oral formulation would be created with hopes of addressing CWD in wild deer and elk. But, as with most commercial products, its future depends on time and money. PREVENT officials project that development of an oral vaccine would take at least four or five? years and $3 million in funding if the process went flawlessly. So far, no one has stepped forward to pick up the tab, and PREVENT is making no promises regarding the future product's effectiveness and utility.

"It is important to remember that, while this vaccine candidate may hold promise for helping manage CWD in the future, it is most likely far removed, and now is not the time to back off from other control measures," said Davin Lopez, CWD Coordinator for the WI DNR. Lopez and other CWD managers hope the potential vaccine will maximize the effectiveness of their future CWD programs, but they are under no illusions as to the reality of managing the disease across the landscape. "If or when a vaccine becomes a reality, its utility will, in part, depend upon how many animals it needs to be applied to, over what geographic area, and for how long."

While the prospect of an effective tool against the seemingly irrepressible disease is tantalizing, it remains to be seen how effective, if at all, the new technology will be when it is put to the test of real-world conditions. "Does it protect? That's the million dollar question for which we have no answer," Napper conceded.

You can?hear audio recordings of the WI DNR meeting and view Dr. Napper's presentation by visiting the WI DNR CWD Research page. (mcd)