Grass plants can transport infectious prions May 16, 2015

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Grass plants can transport infectious prions May 16, 2015

Unread postby Horizontal Hunter » Tue May 19, 2015 1:09 pm

Grass plants can bind, uptake and transport infectious prions, according to researchers at The University of Texas Health Science Center at Houston (UTHealth). The research was published online in the latest issue of Cell Reports.

Prions are the protein-based infectious agents responsible for a group of diseases called transmissible spongiform encephalopathy, which includes bovine spongiform encephalopathy (mad cow disease) in cattle, scrapie in sheep, variant Creutzfeldt-Jakob disease in humans and chronic wasting disease (CWD) in deer, elk and moose. All are fatal brain diseases with incubation periods that last years.

CWD, first diagnosed in mule deer in Colorado in the late 1960s, has spread across the country into 22 states, according to the Centers for Disease Control and Prevention (CDC), including the counties of El Paso and Hudspeth in Texas. In northeastern Colorado and southeastern Wyoming, the disease is endemic. Soto's team sought to find out why.
"There is no proof of transmission from wild animals and plants to humans," said lead author Claudio Soto, Ph.D., professor of neurology at UTHealth Medical School and director of the UTHealth George and Cynthia W. Mitchell Center for Alzheimer's Disease and Other Brain Related Illnesses. "But it's a possibility that needs to be explored and people need to be aware of it. Prions have a long incubation period."
Soto's team analyzed the retention of infectious prion protein and infectivity in wheat grass roots and leaves incubated with prion-contaminated brain material and discovered that even highly diluted amounts can bind to the roots and leaves. When the wheat grass was consumed by hamsters, the animals were infected with the disease. The team also learned that infectious prion proteins could be detected in plants exposed to urine and feces from prion-infected hamsters and deer.

Read More:

http://phys.org/news/2015-05-grass-infe ... rions.html

A very interesting read.

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Small loop in human prion protein prevents chronic wasting d

Unread postby Horizontal Hunter » Tue May 19, 2015 1:12 pm

Chronic wasting disease (CWD)—an infectious disease caused by prions—affects North American elk and deer, but has not been observed in humans. Using a mouse model that expresses an altered form of the normal human prion protein, researchers at University of California, San Diego School of Medicine have determined why the human proteins aren't corrupted when exposed to the elk prions. Their study, published Feb. 23 in the Journal of Clinical Investigation, identifies a small loop in the human prion protein that confers resistance to chronic wasting disease.

"Since the loop has been found to be a key segment in prion protein aggregation, this site could be targeted for the development of new therapeutics designed to block prion conversion," said Christina Sigurdson, DVM, PhD, associate professor at UC San Diego and UC Davis and senior author of the study.

Prions aren't microorganisms like bacteria or viruses; they're simply protein aggregates. Some prion diseases are caused by an inherited genetic mutation, while others are caused by exposure to infectious prions in food. Acquired prion diseases are triggered when a foreign, misfolded prion protein causes the body's own natural prion proteins to misfold and aggregate. In addition to chronic wasting disease, examples include scrapie and bovine spongiform encephalopathy (or "mad cow disease") in animals and variant Creutzfeldt-Jakob disease in humans. In humans, prion diseases can cause a variety of rapidly progressive neurological symptoms, such as difficulty walking and speaking, and dementia. These diseases are 100 percent fatal and there is currently no effective treatment.
"We suspected that a loop in the human prion protein structure may block the elk prions from binding, as the sequences did not appear to be compatible," Sigurdson said.
To test this hypothesis, Sigurdson and her team developed a transgenic mouse that expresses a prion protein that's identical to the human version—except for a small loop, which they swapped out for the elk prion sequence. When these mice were exposed to the elk prions, they developed chronic wasting disease.

Read More:
http://medicalxpress.com/news/2015-02-s ... tml#inlRlv

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Re: Grass plants can transport infectious prions May 16, 201

Unread postby RED OAK » Tue May 19, 2015 2:15 pm

Interesting...Thanks for sharing.

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Re: Grass plants can transport infectious prions May 16, 201

Unread postby JoeRE » Tue May 19, 2015 11:28 pm

Interesting...hay is transported all across the nation. If this transmission method holds up in further tests it will blow all current CWD containment strategies out of the water.
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Re: Grass plants can transport infectious prions May 16, 201

Unread postby dan » Tue May 19, 2015 11:55 pm

JoeRE wrote:Interesting...hay is transported all across the nation. If this transmission method holds up in further tests it will blow all current CWD containment strategies out of the water.

One would think so... But when they discovered it was spread thru urine based scents it changed nothing... They still sell it and ship it across the country and into other countries. And when they found out it was spread from scavenger bird and animal feces it changed nothing... Even though an eagle, vulture, crow, hawk, etc is know to fly hundreds of miles.

When they found out it was spread thru soil they did nothing to stop the sale or movement of soil.

So, I wouldn't doubt it if this to just gets washed under the fence because it does not fit the true agenda of most of the wildlife agencies that are promoting lower populations.
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Re: Grass plants can transport infectious prions May 16, 201

Unread postby JoeRE » Wed May 20, 2015 5:29 am

Good point Dan...it probably will go as you predict.
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A more detailed article from the University of Texas

Unread postby Horizontal Hunter » Tue Jun 02, 2015 9:14 am

An infectious brain disease that has been killing deer, elk and moose both in the wild and on “captive farms” continues to stalk the land, expanding its domain to 23 states and two Canadian provinces since it was first identified in captive mule deer in a Colorado research facility in 1967.

Known as chronic wasting disease, or CWD, it has baffled scientists for decades. Where did it come from, and why is it spreading across the landscape? What health risks might it pose to humans who eat parts of infected animals? And can cattle get it from infected deer, elk, and moose, thus introducing it into the human food chain?


Cow elk with symptoms of chronic wasting disease. Credit: Dr. Terry Kreeger, Wyoming Game and Fish Department, and the Chronic Wasting Disease Alliance.

Recent research, primarily funded by the National Institutes of Health, has opened the door to one of the reasons this disease is so pervasive — and actually endemic in a large swath of land in northeastern Colorado and southeastern Wyoming.

According to researchers at The University of Texas Health Science Center at Houston (UTHealth), grass plants can bind, uptake and transport infectious prions. Why this is so important takes some understanding of what prions are.

Much smaller than bacteria, prions are single proteins that cannot be destroyed by typical “kill strategies” such as extreme heat or ultraviolet light.

“With prions, nothing like that works,” said Claudio Soto, Ph.D., a UTHealth researcher and lead author of an article about the topic published May 26, 2015, in Cell Reports.

These protein-based infectious agents cause the characteristic spongy degeneration of the brain, leading to emaciation, abnormal behavior, loss of bodily functions, and death. As such, they are responsible for a group of fatal diseases referred to as transmissible spongiform encephalopathy (TSE). The group includes so-called “mad cow disease” (bovine spongiform encephalopathy, or BSE) in cattle, scrapie in sheep, and variant Creutzfeldt-Jakob disease in humans, which, according to the World Health Organization, has been “strongly linked” to eating beef products contaminated with central nervous system tissue, such as spinal cord and brain, from cows infected with mad cow disease.

Soto’s team analyzed the retention of CWD and other infectious prion proteins and their infectivity in wheat grass roots and leaves that had been incubated with prion-contaminated material. They discovered that even highly diluted amounts of the material can bind to the roots and leaves. From there, they fed the wheat grass to hamsters, which became infected with the disease.

The team also found the infectious prion proteins in plants that had been exposed to urine and feces from prion-infected hamsters and deer.

In addition, the team found that plants can uptake prions from contaminated soil and transport them to different parts of the plant. By doing this, the plants can act as a carrier of CWD.

This means, Soto said, that plants may play an important role in environmental prion contamination and the horizontal transmission of the disease. (Horizontal transmission occurs when an infectious agent is transmitted between members of the same species.)

Scientists already knew that these CWD prions are good at binding to soil, especially clay-based soils, and that they can persist there. Soto said that when some of the soil where an infected dead animal had been buried was injected into research animals several years after it had been buried, the injected animals came down with prion disease.

The question then became: Can these prions bind to plants?


Distribution of chronic wasting disease in North America, May 2015. Credit: U.S. Geological Survey.

“Surprisingly, we found that they do bind to plants very efficiently,” he said. “Even more surprisingly, plants infected with the prions were able to transmit the disease when animals were fed the contaminated plants.”

Soto warns that there is a good possibility that prions have been progressively accumulating in the environment.

“We have to be careful about the potential dangers of this,” he said. “We need to take precautions.”

Again, these prions are persistent. For example, in 1985 when the Colorado Division of Wildlife tried to eliminate CWD from a research facility by treating the soil with chlorine, removing the treated soil, and applying an additional chlorine treatment before letting the facility remain vacant for more than a year, they were unsuccessful in eliminating CWD from the facility.

‘Nasty nature of this disease’

Matt Dunfee, coordinator of the Chronic Wasting Disease Alliance, told Food Safety News that the new research findings about grass plants provide laboratory and experimental documentation that prions do attach to plants.

“It underscores the nasty nature of this disease and the challenge it is to manage it on a natural landscape,” he said. “It’s hard to contain, especially when it spreads through the soil or on plants. We haven’t been able to eliminate it on a natural landscape known to be infected.”

He pointed out that an infected animal can shed the disease a lot over a year (via urine and feces). And its decomposing body can further infect the soil and therefore the plants.

What about humans?

Can humans who eat deer, elk or moose meat from animals infected with CWD get a human variant of this brain disease? That’s not a far-fetched question considering the strong link between mad cow disease and variant Creutzfeldt-Jakob disease in humans.

According to the Center for Food Safety’s timeline for mad cow disease, the first diagnosis of BSE as a new disease in cattle, similar to scrapie in sheep, occurred in 1986. In the early 1990s, the British government said that the disease presented no threat to humans — that cattle were a “dead-end host.”

But in 1995, three people died of variant Creutzfeldt-Jakob disease. The next year, the British government announced that mad cow disease could indeed be transmitted to humans. After that point, 4.5 million cattle were destroyed.

Livestock experts said the cows likely got BSE from eating ground-up sheep that had been infected with scrapie, which is also a prion-caused brain disease. Many people who believed that cows are vegetarians were horrified to learn that beef cattle were actually being fed ground-up dead animals and chicken litter.

With cases of the human form of mad cow disease being reported from other countries, including the U.S. and Japan, governments around the world passed bans on feeding anything to cattle that contained infectious materials, such as those from spinal cords and brains. Many slapped import bans on beef from countries that had cases of BSE.

As for CWD and any risks to humans, the alliance says there is currently no solid evidence that humans can get it from deer, elk or moose. Most researchers agree with that. According to the group, the diseases (BSE and CWD) are “distinctly different.”

The World Health Organization has also weighed in, stating that after reviewing the available scientific information, its conclusion is that “currently there is no evidence that CWD can be transmitted to humans.”

Even so, the alliance notes that public health officials recommend that human exposure to the CWD infectious agent be avoided as agencies continue to evaluate any potential health risk.

Dunfee added that Wyoming did a 13-year study in which cows were put in deer pens heavily infected with CWD, and none of the cows became infected.

The U.S. Centers for Disease Control and Prevention (CDC) reviewed clinical records and pathology studies of three cases of sporadic Creutzfeldt-Jakob disease in 1997-98 in young adults who had eaten venison, and that review failed to find a causal link to CWD.

The same was true for other cases involving people who had eaten deer or elk meat, although the CDC report contains these words of caution: “Surveillance for human prion diseases, particularly in areas where CWD has been detected, remains important to effectively monitor the possible transmission of CWD to humans.”

The report also pointed out that “because of the long incubation period associated with prion diseases, convincing negative results from epidemiological and experimental laboratory studies would likely require years of follow-up.”

Soto would agree. He said that even though there have been no confirmed cases of infections in humans from CWD, the public should know that “it’s a possibility that needs to be explored.”

“I don’t want to scare people,” he said, “but these (CWD) prions are accumulating, and prions have a long incubation period — sometimes as long as 30 to 40 years in humans.”

Food safety tips


A pair of mule deer in Montana.

CDC advises hunters that “to minimize the risk for exposure to the CWD agent,” they should “consult with their state wildlife agencies to identify areas where CWD occurs and continue to follow advice provided by public health and wildlife agencies.”

The agency also advises hunters to avoid eating meat from deer and elk that look sick or test positive for CWD. They should wear gloves when field-dressing carcasses, bone-out the meat from the animal, and minimize handling of brain and spinal cord tissues. As a precaution, they should avoid eating deer and elk tissues known to harbor the CWD agent (e.g., brain, spinal cord, eyes, spleen, tonsils, lymph nodes) from areas where CWD has been identified.

In addition, hunters should wash their hands and instruments thoroughly after field dressing is completed, and they should request that their animal is processed individually, without meat from other animals being added to the meat from their animal.

While out in the field, hunters should be on the lookout for animals that are unusually thin and exhibit behavior such as having trouble walking, as well as those acting tame around humans and allowing someone to approach them. Such circumstances should be reported to a state wildlife agency.

Dunfee said that hunters in most CWD areas are required to turn in the heads of any deer, elk or moose they kill so it can be examined for signs of CWD.

“Hunters are massively helpful in providing surveillance for wildlife agencies,” he noted.

Some states also prohibit “baiting and feeding,” which would include putting out salt for animals because that entices the deer, elk or moose to congregate in an area, which in turn can make them more susceptible to infection with CWD. Also, many states test deer or elk that have been killed by cars primarily because animals with advanced CWD are particularly vulnerable to that sort of accident.

Captive farms


Male and female moose on a farm in Sweden.

It’s not just hunters who can be exposed to CWD. There are many “captive farms” in the U.S. and elsewhere where deer and elk are raised for their meat, antlers and hides. In some cases, the animals are confined in large fenced areas on ranches or farms so hunters can come in and shoot them.

“It’s a huge industry,” said Dunfee.

The meat and other products are sold both domestically and overseas. But precautions need to be taken. In 2008, elk meat sold at a farmer’s market in Longmont, Colorado, was found to come from a captive elk infected with CWD.

But CWD can also be endemic in some wild herds, and though states have tried various methods to “wipe it out,” nothing has worked, although progress has been made in monitoring it.

“We’re probably going to have to deal with this (CWD) in perpetuity,” Dunfee said. “There probably will never be a silver bullet. The reality is that you’d never get all the infected animals on the landscape.”

Even so, states without CWD are taking measures to try and keep it out of their state.

Read More:

http://www.foodsafetynews.com/2015/06/r ... WyR7c9Viko

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