Scrapie could breach the species barrier



INRA scientists have shown for the first time that the pathogens responsible for scrapie in small ruminants (prions) have the potential to convert the human prion protein from a healthy state to a pathological state.

In mice models reproducing the human species barrier, this prion induces a disease similar to Creutzfeldt-Jakob disease. These primary results published in Nature Communications on 16 December 2014, stress the necessity to reassess the transmission of this disease to humans.

Scrapie is a neurodegenerative disease that has been known for centuries and which affects sheep and goats. Similar to Bovine Spongiform Encephalopathy (BSE) or mad cow disease, scrapie is caused by a transmissible pathogen protein called prion.

However, and contrary to BSE1, epidemiological studies have never been able to establish a link between this disease and the occurrence of prion diseases in humans. “Risks of transmitting scrapie to humans (zoonose) were hitherto considered negligible because of the species barrier that naturally prevents prion propagation between species”, said Olivier Andreoletti, INRA scientist who led the present study.

Researchers at INRA studied the permeability of the human transmission barrier to pathogens responsible for scrapie, using animal models specifically developed for this purpose. This approach previously allowed the confirmation of the zoonotic nature of prions responsible for BSE in cows and of the variant of Creutzfeldt-Jakob disease in humans (vCJD).

Unexpectedly, in these rodent models, certain pathogens responsible for scrapie were able to cross the transmission barrier. Moreover, the pathogens that propagated through this barrier were indistinguishable from the prions causing the sporadic form of Creutzfeldt-Jakob disease (sCJD). This data suggest a potential link between the occurrence of certain sCJD and these animal prions.

“Since CJD is scarce, about 1 case per million and per year, and incubation periods are usually long -several decades- it is extremely difficult for epidemiological studies to try and make this link”, explains Olivier Andreoletti.

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New approach for tuberculosis drugs

A novel scaffold-molecule allows developing new anti-tuberculosis drugs. (Montage: Keystone / Science Photo Library / Eye of Science)

In the past 50 years, only one new tuberculosis drug has come on to the market, yet many more active substances are urgently needed.

Current treatments increasingly fail due to multidrug-resistant pathogens. ETH researchers have now applied to patent a novel approach for developing new tuberculosis drugs.

Consumption was one of the worst known diseases of the 18th century. Thanks to medical advances, the number of deaths from this lung disease – which is today known as tuberculosis – has declined significantly. Efforts to eradicate the disease in the 1950s and 1960s resulted in a wide range of new drugs entering the market.

And yet 1.4 million people still continue to die each year from tuberculosis. Multidrug-resistant strains of the disease-causing pathogen are especially dangerous because they can no longer be treated with today’s drugs (see box). “In the past 50 years, only one new tuberculosis drug has come on to the market, and that was in 2012,” says Karl-Heinz Altmann, Professor of Pharmaceutical Biology at ETH Zurich. New active substances that are able to kill multidrug-resistant strains of the disease are therefore urgently needed. Altmann and his team have now laid the foundation for new tuberculosis drugs, and they were inspired by a bacteria-derived antibiotic called pyridomycin.

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Researcher Testing Biological Treatment for Pathogens That Are Killing Honeybees and Bats

English: Little brown bat with white-nose syndrome in Greeley Mine, Vermont, March 26, 2009. (Photo credit: Wikipedia)

A researcher at Georgia State University is studying a new, biological treatment for bacterial and fungal pathogens that are killing honeybees and bats in record numbers.

Dr. Christopher Cornelison, a postdoctoral researcher, is testing how effective Rhodococcus rhodochrous, a species of bacteria, is in fighting pathogens affecting honeybees and bats.

In honeybees, Chalkbrood disease has contributed to the number of managed honeybee colonies in the U.S. being cut in half, a phenomenon known as Colony Collapse Disorder. Since 2006, White-Nose Syndrome has killed an estimated 7 million bats in North America, the steepest wildlife decline in the past century.

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New sensor to detect harmful bacteria on food industry surfaces

Listeria monocytogenes has a hospitalisation rate of 92 percent

A new device designed to sample and detect foodborne bacteria is being trialled by scientists at the University of Southampton.

The Biolisme project is using research from the University to develop a sensor capable of collecting and detecting Listeria monocytogenes on food industry surfaces, thereby preventing contaminated products from entering the market.

Listeria monocytogenes is a pathogen that causes listeriosis, an infection with symptoms of fever, vomiting and diarrhoea, that can spread to other parts of the body and lead to more serious complications, like meningitis.

Transmitted by ready-to-eat foods, such as milk, cheese, vegetables, raw and smoked fish, meat and cold cuts, Listeria monocytogenes has the highest hospitalisation (92 per cent) and death (18 per cent) rate among all foodborne pathogens. Listeriosis mainly affects pregnant women, new-born children, the elderly and people with weakened immune systems.

Current techniques to detect the bacteria take days of testing in labs, but the new device aims to collect and detect the pathogen on location within three to four hours. This early and rapid detection can avoid the cross contamination of ready-to-eat food products.

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Man’s best friend: Common canine virus may lead to new vaccines for deadly human diseases

Researchers at the University of Georgia have discovered that a virus commonly found in dogs may serve as the foundation for the next great breakthrough in human vaccine development.

Although harmless in humans, parainfluenza virus 5, or PIV5, is thought to contribute to upper respiratory infections in dogs, and it is a common target for canine vaccines designed to prevent kennel cough. In a paper published recently in PLOS ONE, researchers describe how this virus could be used in humans to protect against diseases that have eluded vaccine efforts for decades.

“We can use this virus as a vector for all kinds of pathogens that are difficult to vaccinate against,” said Biao He, the study’s principal investigator and professor of infectious diseases in UGA’s College of Veterinary Medicine. “We have developed a very strong H5N1 flu vaccine with this technique, but we are also working on vaccines for HIV, tuberculosis and malaria.”

PIV5 does not cause disease in humans, as our immune system is able to recognize and destroy it. By placing antigens from other viruses or parasites inside PIV5, it effectively becomes a delivery vehicle that exposes the human immune system to important pathogens and allows it to create the antibodies that will protect against future infection.

This approach not only ensures full exposure to the vaccine but also is much safer because it does not require the use of attenuated, or weakened, pathogens. For example, an HIV vaccine delivered by PIV5 would contain only those parts of the HIV virus necessary to create immunity, making it impossible to contract the disease from the vaccine.

“Safety is always our number one concern,” said He, who is also a Georgia Research Alliance distinguished investigator and member of the Faculty of Infectious Diseases. “PIV5 makes it much easier to vaccinate without having to use live pathogens.”

Using viruses as a delivery mechanism for vaccines is not a new technique, but previous efforts have been fraught with difficulty. If humans or animals already possess a strong immunity to the virus used for delivery, the vaccine is unlikely to work, as it will be destroyed by the immune system too quickly.

“Pre-existing immunity to viruses is the main reason most of these vaccines fail,” He said.

But in this latest study, He and his colleagues demonstrate that immunity to PIV5 does not limit its effectiveness as a vaccine delivery mechanism, even though many animals-including humans- already carry antibodies against it.

In their experiments, the researchers found that a single dose inoculation using PIV5 protected mice from the influenza strain that causes seasonal flu. Another single dose experimental vaccine also protected mice from the highly pathogenic and deadly H5N1 virus commonly known as bird flu.

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via University of Georgia – James Hataway

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