Chronic wasting disease (CWD) is a relentless epidemic disorder caused by infectious prions that threatens the survival of cervid populations and raises increasing public health concerns in North America. In Europe, CWD was detected for the first time in wild Norwegian reindeer (Rangifer tarandus) and moose (Alces alces) in 2016. In this study, we aimed at comparing the strain properties of CWD prions derived from different cervid species in Norway and North America.
Using a classical strain typing approach involving transmission and adaptation to bank voles (Myodes glareolus), we found that prions causing CWD in Norway induced incubation times, neuropathology, regional deposition of misfolded prion protein aggregates in the brain, and size of their protease-resistant core, different from those that characterize North American CWD. These findings show that CWD prion strains affecting Norwegian cervids are distinct from those found in North America, implying that the highly contagious North American CWD prions are not the proximate cause of the newly discovered Norwegian CWD cases.
In addition, Norwegian CWD isolates showed an unexpected strain variability, with reindeer and moose being caused by different CWD strains. Our findings shed light on the origin of emergent European CWD, have significant implications for understanding the nature and the ecology of CWD in Europe, and highlight the need to assess the zoonotic potential of the new CWD strains detected in Europe.
Studies in bank voles reveal strain differences between chronic wasting disease prions from Norway and North America
PNAS
Romolo Nonno, Michele A. Di Bari, Laura Pirisinu, Claudia D’Agostino, Ilaria Vanni, Barbara Chiappini, Stefano Marcon, Geraldina Riccardi, Linh Tran, Turid Vikøren, Jørn Våge, Knut Madslien, Gordon Mitchell, Glenn C. Telling, Sylvie L. Benestad, and Umberto Agrimi
I didn’t blog for the last two months. I haven’t done that in 16 years. I haven’t done that ever. Throw in the news and I haven’t done it, ever, in 28 years.
Only once have I ever stopped daily writing over that time period – one week in 2004.
But, I keep falling and my head hurts, so I’m easing back in because it keeps my brain active.
I haven’t had a pay cheque in four years. There’s lots of work at home jobs out there now, which is ironic because I got fired by Kansas State for working at home.
Anyone got work for me?
I’m wonderin’ how this will go.
Got lotsa support from Amy and Sorenne and the rest of the fam.
Jim Robbins of the New York Times reports on the wonderin’ of researchers who ask, Are the wolves of Yellowstone National Park the first line of defense against a terrible disease that preys on herds of wildlife?
That’s the question for a research project underway in the park, and preliminary results suggest that the answer is yes. Researchers are studying what is known as the predator cleansing effect, which occurs when a predator sustains the health of a prey population by killing the sickest animals. If the idea holds, it could mean that wolves have a role to play in limiting the spread of chronic wasting disease, which is infecting deer and similar animals across the country and around the world. Experts fear that it could one day jump to humans.
“There is no management tool that is effective” for controlling the disease, said Ellen Brandell, a doctoral student in wildlife ecology at Penn State University who is leading the project in collaboration with the U.S. Geological Survey and the National Park Service. “There is no vaccine. Can predators potentially be the solution?”
Many biologists and conservationists say that more research would strengthen the case that reintroducing more wolves in certain parts of the United States could help manage wildlife diseases, although the idea is sure to face pushback from hunters, ranchers and others concerned about competition from wolves.
Chronic wasting disease, a contagious neurological disease, is so unusual that some experts call it a “disease from outer space.” First discovered among wild deer in 1981, it leads to deterioration of brain tissue in cervids, mostly deer but also elk, moose and caribou, with symptoms such as listlessness, drooling, staggering, emaciation and death.
It is caused by an abnormal version of a cell protein called a prion, which functions very differently than bacteria or viruses. The disease has spread across wild cervid populations and is now found in 26 states and several Canadian provinces, as well as South Korea and Scandinavia.
The disease is part of a group called transmissible spongiform encephalopathies, the most famous of which is bovine spongiform encephalopathy, also known as mad cow disease. Mad cow in humans causes a variant of Creutzfeldt-Jakob disease, and there was an outbreak among people in the 1990s in Britain from eating tainted meat.
Cooking does not kill the prions, and experts fear that chronic wasting disease could spread to humans who hunt and consume deer or other animals that are infected with it.
The disease has infected many deer herds in Wyoming, and it spread to Montana in 2017. Both states are adjacent to Yellowstone, so experts are concerned that the deadly disease could soon makes its way into the park’s vast herds of elk and deer.
Unless, perhaps, the park’s 10 packs of wolves, which altogether contain about 100 individuals, preyed on and consumed diseased animals that were easier to pick off because of their illness (The disease does not appear to infect wolves).
“Wolves have really been touted as the best type of animal to remove infected deer, because they are cursorial — they chase their prey and they look for the weak ones,” said Ms. Brandell. By this logic, diseased deer and other animals would be the most likely to be eliminated by wolves.
Preliminary results in Yellowstone have shown that wolves can delay outbreaks of chronic wasting disease in their prey species and can decrease outbreak size, Ms. Brandell said. There is little published research on “predator cleansing,” and this study aims to add support for the use of predators to manage disease.
In March, 1996, the UK government confirmed what had been known for years: bovine spongiform encephalopathy (or mad cow disease) was killing humans in the UK.
The various forms of transmissible encephalopathies have different names according to the species – scrapie in sheep, feline spongiform encephalopathy in cats, Creutzfeldt-Jacob disease in humans, chronic wasting disease in deer and elk.
But they’re all the same affliction, caused by infectious proteins, or prions.
I haven’t been following the CWD outbreak in deer, but it seems to be where BSE was about 1993: There’s this mysterious new disease no one ever thoughts would cross over to humans, but now, maybe?
Jim Robbins of the New York Times writes that, as darkness closed in, one hunter after another stopped at this newly opened game check station, deer carcasses loaded in the beds of their pickups.
They had been given licenses for a special hunt, and others would follow. Jessica Goosmann, a wildlife technician with Montana’s Fish, Wildlife & Parks Department, stepped outside to greet them, reaching for the neck of each freshly killed deer to cut an incision and remove a lymph node for testing.
On the edge of this south-central Montana village, where deer hunting is a way of life, the game check station has become the front line of the state’s efforts to stop the spread of a deadly infection known as chronic wasting disease.
It has ravaged deer herds throughout the United States and Canada and forced the killing of thousands of infected animals in 24 states and three Canadian provinces. It has also been found in Norway and South Korea. With the disease widespread in Wyoming, the Dakotas and the province of Alberta, Montana officials had been bracing for its emergence.
So in November, when biologists discovered it in six deer in this part of Montana and in another near the Canadian border, officials began setting up special hunts and stations for testing.
“It wasn’t a surprise that we found it,” said John Vore, game management bureau chief for the Montana Department of Fish, Wildlife & Parks. “It was a disappointment, but not a surprise.”
On Friday, the department announced that two more deer from this region, taken early in the special hunt, tested positive for the disease. Other test results are pending.
Chronic wasting disease is a contagious neurological disease that infects elk, deer, moose and caribou, and reduces their brains to a spongy consistency. Animals become emaciated, behave strangely and eventually die. It’s not known to be transferred to humans. Neither is it known to be spread from wild to domestic animals. There is no treatment, although a vaccine has been successful in tests in wild deer.
It is among a class of diseases known as transmissible spongiform encephalopathy, or TSE. Most experts believe the infectious agent is something called a prion, a misfolded cellular protein found in the nervous system and lymph tissue. The disease was first noted in captive deer in Colorado in the 1960s. The most closely related animal disease is scrapie in sheep.
“It’s a very unusual disease,” said Matthew Dunfee, an expert at the Wildlife Management Institute in Fort Collins, Co. and project director for the Chronic Wasting Disease Alliance. “Some experts say it’s a disease from outer space.”
Investigators at the New York University School of Medicine have developed a weakly successful vaccine against Chronic Wasting Disease (CWD) in white-tailed deer[1]. CWD is a prion disease which is common in cervids and can cause progressive, irreversible degeneration and death. Though I could not locate any evidence of this disease making the species jump like bovine spongiform encephalitis did, the authors contend that given the large numbers of deer and elk suffering from this disease, there is a possible risk for human infection as well.
In this study, the investigators comment in the abstract:
In the current study, white-tailed deer were orally inoculated with attenuated Salmonella expressing PrP, while control deer were orally inoculated with vehicle attenuated Salmonella. Once a mucosal response was established, the vaccinated animals were boosted orally and locally by application of polymerized recombinant PrP onto the tonsils and rectal mucosa. The vaccinated and control animals were then challenged orally with CWD-infected brain homogenate. Three years post CWD oral challenge all control deer developed clinical CWD (median survival 602 days), while among the vaccinated there was a significant prolongation of the incubation period (median survival 909 days; p = 0.012 by Weibull regression analysis) and one deer has remained CWD free both clinically and by RAMALT and tonsil biopsies. This negative vaccinate has the highest titers of IgA in saliva and systemic IgG against PrP. Western blots showed that immunoglobulins from this vaccinate react to PrPCWD. We document the first partially successful vaccination for a prion disease in a species naturally at risk.
References:
1.Goñi, F., Mathiason, C., Yim, L., Wong, K., Hayes-Klug, J., Nalls, A., Peyser, D., Estevez, V., Denkers, N., Xu, J., Osborn, D., Miller, K., Warren, R., Brown, D., Chabalgoity, J., Hoover, E., & Wisniewski, T. (2015). Mucosal immunization with an attenuated Salmonella vaccine partially protects white-tailed deer from chronic wasting disease Vaccine, 33 (5), 726-733 DOI: 10.1016/j.vaccine.2014.11.035
In a letter sent Friday to Secretary of Agriculture Tom Vilsack and top USDA officials, the six Democrats cited an Indianapolis Star investigation this spring that uncovered case after case linking the captive deer industry to the spread of various diseases.
“Considering USDA’s limited resources, it would be prudent for the agency to adopt a precautionary approach, consistent with its regulatory authority, and prohibit interstate transport of captive-bred cervids in order to quell the burgeoning threats the inhumane canned-hunting industry poses to the health of livestock, native wildlife and even humans,” the letter says. “Cervid” is the scientific name for deer.
At least 21 states already prohibit the importation of certain species of captive deer, fearing imported animals could infect wild herds with chronic wasting disease, an always-fatal deer disease similar to mad cow.
CWD has not been found in Indiana, which has about 400 deer farms, many of which ship deer in and out of the state.
The Star’s investigation revealed that the 10,000 deer and elk farmers in the U.S. are shipping an unprecedented number of deer and elk across state lines to supply the burgeoning high-fence hunting industry. Deer and elk are bred for abnormally large antlers, some bigger than the established world record for wild animals. Top breeding stock can fetch six-figure prices.
The Star’s investigation revealed that bovine tuberculosis has been found on 50 captive deer and elk herds, and researchers say they believe that in at least four instances the disease jumped from captive deer and elk to cattle. One such case was in Indiana.
The Star’s investigation also uncovered circumstantial evidence that the industry may have helped accelerate the spread of CWD, which has been found in 22 states.
Using a classical strain typing approach involving transmission and adaptation to bank voles (Myodes glareolus), we found that prions causing CWD in Norway induced incubation times, neuropathology, regional deposition of misfolded prion protein aggregates in the brain, and size of their protease-resistant core, different from those that characterize North American CWD. These findings show that CWD prion strains affecting Norwegian cervids are distinct from those found in North America, implying that the highly contagious North American CWD prions are not the proximate cause of the newly discovered Norwegian CWD cases. 
