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Posts Tagged ‘influenza’

They still get sick and die; they just can't spread the disease

The transgenic cluckers still died from bird flu, however, so there’s still much more to be done before scientists produce a truly flu-free bird.

Generating flu-resistant birds may be more effective than giving vaccinations to an entire flock, said Dr. Laurence Tiley, a veterinarian and lecturer in molecular virology at the University of Cambridge, England, one of the authors of the chicken study. Vaccinated birds may not develop flu, but the virus can still replicate in their bodies and be transmitted to other unvaccinated fowl, he explained in a podcast with the journal Science, which publishes the study tomorrow. Besides, just like with human influenza, there are plenty of strains, and vaccines don’t cover all of them.

The new genetic modification is basically the opposite — birds will still get sick and die, but they won’t pass on the virus to other birds, a major advancement for animals that generally live in very close quarters. The lack of transmission also means the virus will be less likely to spread to people.

“You reduce the likelihood of transmission onto those people who are in contact with them, and therefore reduce the potential of avian flu strains to jump from birds into humans,” he said.

The chickens were modified to express a piece of RNA that acts as a decoy to a key viral enzyme. The polymerase is tricked into binding to this RNA, rather than binding to the virus‘ genome and helping it replicate. The result is that the virus does not spread to other chickens.

“It diverts the polymerase away from the job it’s supposed to be doing,” Tiley said.

The decoy is specific to influenza A, which is responsible for the types of flu we all hear about — H1N1, avian flu, etc. — so it wouldn’t be of much use against other pathogens. But the technique could inform disease-resistance research in other species, Tiley said, especially pigs, turkeys, ducks and quail.

The proof of concept is a major step by itself, noted Helen Sang, from The Roslin Institute at the University of Edinburgh, one of the co-authors. This particular type of resistance could never be achieved through traditional breeding, thanks to the metamorphic nature of viruses.

Genetic modification to resist disease is nothing new to the food supply. Much of the American agricultural industry grows crops that have been genetically altered to resist diseases, pests and proprietary weed killers. But modified animals are relatively newer, in large part because the issue is so controversial.

Tiley noted opposition to genetic modification in Europe, including his home country, and said he hoped the new research would cast the possibilities of genetic modification in a new, more positive light.

But even in this country, genetically altered chickens are probably a long way off. GM salmon, which will likely become the first transgenic animal approved for human consumption, has spent 15 years mired in red tape, and the organic food movement has led opposition to genetically modified staple crops like sugar and corn. So it will likely be years yet before butchers start selling transgenic chicken cutlets.

First, it should be a strain of influenza. As anyone who has suffered through a bout of flu knows, it affects the respiratory tract, so sneezing and coughing make it easy to infect anyone within a three-foot radius. The virus must originate in a major city with plenty of airport traffic, to ensure that it jumps continents. Arising during the winter would speed its spread too, because the “normal” colds or flus people typically catch at that time of year could throw health officials off the trail of the real megabug, says Andrew Pekosz, a virologist and immunologist at Johns Hopkins University. The idea seems to freak him out. “With everybody expressing similar symptoms, we’d end up chasing, chasing, chasing, but always being a few steps behind, never really able to interrupt the spread.”

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The influenza A virus contains eight individual single-stranded RNA segments, each of which has to make protein as well as new segments, in processes called transcription and replication. The multitasking strands must prioritize their work, so they must start with transcription and move on to replication. Researchers at Mount Sinai School of Medicine in New York figured out how to prevent RNA from starting the replication process. Their results were published June 1 online in the Proceedings of the National Academy of Sciences.

Using a novel process called deep sequencing, the team found a small viral RNA segment, or svRNA, that is integral to the change. Inhibiting the svRNA from doing its work stymies replication, and therefore slows the spread of the virus.

Even better, influenza A shares this trait with its viral cousins, influenza B and C, meaning the svRNA switch can be used to stop all kinds of flu -- even the H1N1 flu. As an added bonus, if the virus is prevented from replicating, it stays in transcription mode and produces more proteins. This helps the body's immune system build up its defenses, according to Benjamin tenOever, an assistant microbiology professor at Mount Sinai and a study author.

The process used to make this discovery is also groundbreaking, the researchers say. The deep sequencing allowed the scientists to obtain millions of small RNAs from cells in an unbiased fashion, according to a Mount Sinai release.

The next step is to find a way to introduce RNA "antagonists" to inhibit the svRNA's switch function, tenOever says. That's still a long way off, but the knowledge that RNA can be switched off means that a universal flu treatment is a possibility.

[Science Daily]

The sensor detects changes in gene expression that occur in people exposed to viruses like the common cold, flu, or the respiratory syncytial virus.

Led by Dr. Geoffrey Ginsburg, director of Duke's Institute for Genome Science & Policy, the team identified 30 genetic markers that are activated by viruses. In some cases, the changes occurred hours or days before symptoms started.

This approach would let doctors and public-health officials make quick diagnoses before someone even appears sick. Current tests look for presence of the actual pathogen, but that takes longer and doesn't work until a person has symptoms, Ginsburg says.

The team started human trials last year, monitoring 80 people in four studies. Healthy people were exposed to three viral strains, and their blood, urine and saliva were then tested for specific gene signatures that would characterize illness, DangerRoom reports.

The next step is to analyze an ongoing study of Duke freshmen living in dorms. Participants were asked to file daily reports about their health and provide blood and other samples as requested, according to a university news release.

Darpa provided $19.5 million to fund the study, seeing potential in a system that can evaluate military personnel before they're deployed. An early-warning system could also help quarantine troops before they can infect others.

The research could lead to public-health benefits well beyond the military, however. The team also found that genetic signatures for viral infections are different from those triggered by bacterial infections. Definitive information about a patient's ailment can make antibiotic-resistant superbugs less likely, if fewer doctors prescribe antibiotics when they're not necessary.

What's more, public health agencies could use the technology to isolate outbreaks of influenza virus, possibly stemming pandemics before they can spread.

People who are "bridges" among different social groups appear as good vaccination bets

The mathematical model focused on the fact that just a few individuals often form the links between different social groups. It also made use of data that came from back in 2005, when Facebook was only open to college students.

The relationships and interactions on five university campuses provided a useful starting scenario for the model to recognize clusters of people and predict bridges between them.

"When a new virus starts spreading, neither the time nor the necessary doses of vaccine to immunize everyone is available," said Marcel Salathe, a postdoc biology researcher at Stanford University. So you'd want a strategy that allows you to protect a population as much as possible given the limited resources that you have."

More details on the Stanford work appear in the April 8 issue of the PLoS Computational Biology.

Scientists have made growing use of social networking data that contains once-personal info. HP Labs researchers recently announced that they used Twitter data to predict the box office success of the latest Hollywood films. And the Pentagon's DARPA challenged people to sift through the disinformation available on social networks such as Twitter and hunt down the physical location of 10 red balloons located around the U.S.

[Stanford Report]