spectr17
01-04-2003, 03:48 PM
Jan 3, 2003
Genetics seen as possible key in fight against CWD
Gannett Wisconsin Newspapers and The Associated Press
WAUSAU - The key to eliminating chronic wasting disease from Wisconsin's deer herd might be breeding deer resistant to the disease in addition to killing those susceptible to it, say a pair of Marshfield Medical Research Foundation scientists.
Genetically improving Wisconsin's 1.6 million deer as a way to fight chronic wasting disease is a theory worth considering, but the years of costly research needed and uncertainty of dealing with a wild deer population make a successful outcome unlikely, wildlife experts say.
An editorial in the latest edition of the Wisconsin Medical Journal by Deanna Cross and James K. Burmester, who work at the Marshfield Medical Research Foundation, suggests looking at the genetics of deer to eradicate the fatal brain disease from the herd.
The genetic research to produce CWD-resistant deer is years away, and the practicality of transmitting the genes to wild deer in Wisconsin would be incredibly complicated.
"It's an interesting idea," said Scott Wright, Ph.D., chief of the disease investigation branch of the U.S. Geological Survey's National Wildlife Health Center in Madison. "The model in sheep for scrapie is working. But that's in an inbred population in captivity. The genetic makeup of sheep is also much more clearly defined than that of whitetail deer."
Abnormal proteins called prions cause diseases such as chronic wasting disease in deer and elk, mad cow disease in cattle, new variant Creutzfeldt-Jakob disease in humans and the sheep disease scrapie.
CWD in Wisconsin was discovered in February, the first time it was found east of the Mississippi River. So far, the state Department of Natural Resources has found 48 deer infected with the disease in an area just west of Madison.
Tom Hauge, coordinator of the DNR's program to try to eradicate CWD from the herd, said there have been breeding programs involving sheep to make them resistant to scrapie, but dealing with wild deer would be much different.
"We have considered it as a future technology, but it is not one that is on the shelf that we can pull off and implement with our current situation," he said. "It is future research. Whether or not it delivers a practical alternative to us is probably a ways out."
Cross and Burmester wrote that an in-depth study of the genetics of whitetail deer could determine if some deer are genetically more resistant to CWD.
If scientists discover some form of genetic resistance, the state could breed a herd of genetically resistant deer.
Under such a plan, the state would organize intensive hunts to deplete the populations of deer that are genetically susceptible to the disease. It would also raise resistant bucks and release them into the wild to breed.
"Males are specifically targeted because they breed with more than one female a season, thereby contributing more genetic material to the next generation in a single season," Cross and Burmester wrote. "Continuing this process over several generations would ensure a greater ratio of resistant individuals."
But that plan has some practical limitations associated with wild populations. Assuming you can hunt all of the wild male whitetail deer in Wisconsin, introducing farm-raised, genetically altered males in their place that know nothing about living in the wild will complicate matters further, said Wright, whose National Wildlife Health Center is the Centers for Disease Control and Prevention of wildlife in the United States.
"It's conceptually easy, but extraordinarily impossible," said Wright.
A majority of the state's whitetail deer might be susceptible to CWD, according to preliminary research by Judd Aiken, a professor in the department of animal health and biomedical sciences at the University of Wisconsin-Madison.
But Patrick Bosque, a Denver neurologist and prion researcher, said further research to create a resistant herd will be complex and time-consuming.
Bosque said it isn't yet clear there is any genetic variation that makes a deer resistant to the disease, and the experiment to find a resistant gene could take five to 10 years.
"We just don't know enough about the (CWD) strains," he said.
Genetics seen as possible key in fight against CWD
Gannett Wisconsin Newspapers and The Associated Press
WAUSAU - The key to eliminating chronic wasting disease from Wisconsin's deer herd might be breeding deer resistant to the disease in addition to killing those susceptible to it, say a pair of Marshfield Medical Research Foundation scientists.
Genetically improving Wisconsin's 1.6 million deer as a way to fight chronic wasting disease is a theory worth considering, but the years of costly research needed and uncertainty of dealing with a wild deer population make a successful outcome unlikely, wildlife experts say.
An editorial in the latest edition of the Wisconsin Medical Journal by Deanna Cross and James K. Burmester, who work at the Marshfield Medical Research Foundation, suggests looking at the genetics of deer to eradicate the fatal brain disease from the herd.
The genetic research to produce CWD-resistant deer is years away, and the practicality of transmitting the genes to wild deer in Wisconsin would be incredibly complicated.
"It's an interesting idea," said Scott Wright, Ph.D., chief of the disease investigation branch of the U.S. Geological Survey's National Wildlife Health Center in Madison. "The model in sheep for scrapie is working. But that's in an inbred population in captivity. The genetic makeup of sheep is also much more clearly defined than that of whitetail deer."
Abnormal proteins called prions cause diseases such as chronic wasting disease in deer and elk, mad cow disease in cattle, new variant Creutzfeldt-Jakob disease in humans and the sheep disease scrapie.
CWD in Wisconsin was discovered in February, the first time it was found east of the Mississippi River. So far, the state Department of Natural Resources has found 48 deer infected with the disease in an area just west of Madison.
Tom Hauge, coordinator of the DNR's program to try to eradicate CWD from the herd, said there have been breeding programs involving sheep to make them resistant to scrapie, but dealing with wild deer would be much different.
"We have considered it as a future technology, but it is not one that is on the shelf that we can pull off and implement with our current situation," he said. "It is future research. Whether or not it delivers a practical alternative to us is probably a ways out."
Cross and Burmester wrote that an in-depth study of the genetics of whitetail deer could determine if some deer are genetically more resistant to CWD.
If scientists discover some form of genetic resistance, the state could breed a herd of genetically resistant deer.
Under such a plan, the state would organize intensive hunts to deplete the populations of deer that are genetically susceptible to the disease. It would also raise resistant bucks and release them into the wild to breed.
"Males are specifically targeted because they breed with more than one female a season, thereby contributing more genetic material to the next generation in a single season," Cross and Burmester wrote. "Continuing this process over several generations would ensure a greater ratio of resistant individuals."
But that plan has some practical limitations associated with wild populations. Assuming you can hunt all of the wild male whitetail deer in Wisconsin, introducing farm-raised, genetically altered males in their place that know nothing about living in the wild will complicate matters further, said Wright, whose National Wildlife Health Center is the Centers for Disease Control and Prevention of wildlife in the United States.
"It's conceptually easy, but extraordinarily impossible," said Wright.
A majority of the state's whitetail deer might be susceptible to CWD, according to preliminary research by Judd Aiken, a professor in the department of animal health and biomedical sciences at the University of Wisconsin-Madison.
But Patrick Bosque, a Denver neurologist and prion researcher, said further research to create a resistant herd will be complex and time-consuming.
Bosque said it isn't yet clear there is any genetic variation that makes a deer resistant to the disease, and the experiment to find a resistant gene could take five to 10 years.
"We just don't know enough about the (CWD) strains," he said.