The findings appear in the January issue of the American Journal of Preventive Medicine.

Approximately 60 million American adults are obese, according to the U.S. Centers for Disease Control and Prevention. In 1998, Americans spent about 9 percent of all medical expenses on problems linked to being overweight or obese, the CDC reports.

The new telephone survey of 1,139 adults found that 85 percent supported tax breaks for employers who made exercise space available to employees.

In addition, 73 percent said they'd support government incentives for companies that reduced the cost of health insurance for employees who had healthy lifestyles and shed extra pounds. Seventy-two percent said they would support government policies requiring insurance companies to cover obesity treatment and prevention programs.

"There is growing public advocacy for these kinds of policy changes," Fuemmeler said. "There is also advocacy in the research community for large-scale policy changes. With some push, we might be able to get some changes that would help us better address the obesity epidemic in the country."

But one expert said it will take more than policy changes to get Americans to eat better and exercise more.

"The problem is not necessarily that employers need tax incentives," said Kathryn M. Kolasa, a professor in the department of nutrition services and patient education at East Carolina University. "The employer can expect to realize health-care cost savings and can be motivated by that."

However, "It's not clear what will motivate the employees," Kolasa said.

One problem is misinformation about weight loss. "Most individuals that present for nutrition counseling have significant amounts of misinformation about food and beverages that prevent them from being successful in weight loss or weight management," Kolasa said.

"Also, people continue to say that it costs more money to eat healthy, when it has been demonstrated time and again you can eat healthy at no greater cost," Kolasa added.

She does believe that changes in policy might make it easier for people to take advantage of health-promotion programs.

"Just because an insurance company provides a wellness benefit doesn't mean people will use it," Kolasa said. "I have one patient who was excited to receive the wellness benefit -- six visits with a certified dietitian during the year. Her employer let her take time from work for the first visit, but said subsequent visits would have to be on her time. This same employer allows employees to take time for doctor visits without penalty," she said.

The researchers aren't sure if more Firmicutes makes you fat or if people who are obese grow more of that type of bacteria.

But growing evidence of this link gives scientists a potentially new and still distant way of fighting obesity: Change the bacteria in the intestines and stomach. It also may lead to a way of fighting malnutrition in the developing world.

Nikhil Dhurandhar, a professor of infection and obesity at Louisiana State University's Pennington Biomedical Research Center, wasn't part of the research, but said it may change the way obesity is treated eventually.

"We are getting more and more evidence to show that obesity isn't what we thought it used to be,'' Dhurandhar said. "It isn't just (that) you're eating too much and you're lazy.''

He said the field of "infectobesity'' looks at obesity with multiple causes, including viruses and microbes. In another decade or so, the different causes of obesity could have different treatments. The current regimen of diet and exercise "is like treating all fevers with one aspirin,'' Dhurandhar said.

In one study, Gordon and colleagues looked at what happened in mice with changes in bacteria level. When lean mice with no germs in their guts had larger ratios of Firmicutes transplanted, they got "twice as fat'' and took in more calories from the same amount of food than mice with the more normal bacteria ratio, said Washington University microbiology instructor Ruth Ley, a study co-author.

It was as if one group got far more calories from the same bowl of Cheerios than the other, Gordon said.

In a study of dozen dieting people, the results also were dramatic.

Before dieting, about 3 percent of the gut bacteria in the obese participants was Bacteroidetes. But after dieting, the now normal-sized people had much higher levels of Bacteroidetes - close to 15 percent, Gordon said.

"I think that gut bacteria affects body weight,'' said Virginia Commonwealth University pathology professor Richard Atkinson, who wasn't part of the research team and is president of Obetech Obesity Research Center in Richmond. "I don't think there's any doubt about that and they showed that.''

The growing field of research puts more importance in the trillions of microbes that live in our guts and elsewhere, crediting it with everything from generations of people getting taller to increases in diabetes and asthma.

People are born germ-free, but within days they have a gut blooming with microbes. The microbes come from first foods - either breast milk or formula - the exterior environment, and the way the babies are born, said Stanford University medicine and microbiology professor David Relman, who was not part of the study.

For decades, doctors have treated bacteria in a "warlike'' manner, yet recent research shows that "most encounters we have with microbes are very beneficial,'' Gordon said.

"Much of who we are and what we can do and can't do as human beings is directly related to microbial inhabitants,'' Relman said.

Any insights into how the brain runs and the genes that orchestrate the brain activity are welcomed by neuroscientists. Until now, for instance, scientists have been largely in the dark about how genes shape circuits in the brain to enhance learning and memory.

"This improves the genetic data that is available on Aplysia by several orders of magnitude," said study team member Eric Kandel of Columbia University in New York.

Brain web

The marine slug has a relatively simple nervous system, with about 10,000 large neurons that can be easily identified, compared with about 100 billion neurons in humans. Even so, the animal is capable of learning and its brain cells communicate in ways identical to human neuron-to-neuron messaging.

Like a meticulously-crafted spider web, most neurons sport thousands of strands that connect to other neurons. To journey between certain neurons, a signal must flow along the correct strands and intersections. Similarly, to store a memory that pathway, called a synapse, must be strengthened.

In past studies, scientists have found that once the route-map gets made, the sea slug marks the synapses connecting the relevant neurons. Next time the slug gets pinched, a certain protein gets sent out to all the synapses in a neuron. When the protein reaches a marked synapse, it triggers other molecules there to produce new proteins that strengthen the neuron-to-neuron connection.

Brainy conductor

To find out the genetic conductors of such learning and memory, scientists led by Leonid Moroz of the University of Florida Whitney Laboratory for Marine Bioscience studied gene activity in the sea slug's central nervous system, including genes known to switch on and off during a simple defensive maneuver-when the slug withdraws its gill.

Specifically they looked at the so-called transcriptome, a small percentage of genes that get copied to form molecules of ribonucleic acid (RNA). These molecules deliver directions for making proteins, which are key players in how cells operate.

They found specific genes linked to learning and memory. "We've now identified a whole bunch of receptors for serotonin. So we can see what their function is in various cells and which ones participate in the learning process," Kandel told LiveScience.

The scientists also analyzed 146 human genes implicated in 168 neurological disorders, including Parkinson's and Alzheimer's diseases, and genes controlling aging. They found 104 counterpart genes in Aplysia, suggesting the animal will be a valuable tool in understanding and ultimately treating neurodegenerative diseases.

The study is detailed in the Dec. 29 issue of the journal Cell.

Scientists with the FDA suggest in the Jan. 1 issue of Theriogenology that food from cloned animals does not need to be specially labelled.

"Meat and milk from clones and their progeny is as safe to eat as corresponding products derived from animals produced using contemporary agricultural practices," wrote FDA scientists Larisa Rudenko and John C. Matheson.

Rudenko and Matheson also noted that when the cloned animals reached six to 18 months of age, it was almost impossible to distinguish them from animals that had been traditionally bred.

Food from cloned animals is forbidden for sale in Canada but Health Canada officials noted earlier in the year that they are waiting to evaluate the FDA's findings.

Meanwhile, consumer groups continue to argue that more precautions should be made to protect the safety of the food supply. They argue that food products made from cloned animals must be separated and labelled.

The Consumer Federation of America said the FDA is overlooking research that shows cloning produces more deformed animals than other reproductive technologies.

Carol Tucker Foreman, the federation's director of food policy, is calling on supermarkets to refuse to sell food from clones.

The research, published in the journal Cancer Epidemiology Biomarkers and Prevention, said: "In this large cohort of women ... increased non-occupational physical activity and, in particular, increased household activity, were significantly associated with reduced breast cancer risk, independent of other potential risk factors.

"These results strengthen the consistency of findings about the protective role of physical activity on breast cancer risk."

Some 44,100 cases of breast cancer are diagnosed in the UK every year and more than 12,400 women die from the disease.

Dr Lesley Walker, of Cancer Research UK, which part-funded the study, said: "We already know that women who keep a healthy weight are less likely to develop breast cancer. This study suggests being physically active may also help reduce the risk and that something as simple... as doing the housework can help."

Reda Abdel Halim Farid, a 26-year-old man from a big family living in the Egyptian Delta governorate of Gharbiya, some 90 km north of Cairo, died of the deadly H5N1 virus on Wednesday, became the third casualty in a week after another two members of the family, a 30-year-old woman and a 15-year-old girl, who died on Sunday and Monday respectively.

On the current bird flu situation in Egypt, Egyptian Health Ministry spokesman Abdel Rahman Shahine told Xinhua that the situation seems to be dangerous but it is under control, specially as people start to recognize how dangerous the virus is and directly inform the authorities of any suspected cases.

"H5N1 is a serious threat in Egypt and we set up a plan to take measures in cooperation with other ministries to deal with this problem," Shahine said.

He added that Egypt is cooperating with the World Health Organization and the EU among others to provide some vaccines to face the disease.

For his part, Egyptian Ministry of Environment senior official Ahmed el-Emary said that there would be serious problems during next March, the birds immigration season, when hundreds of birds come from the EU through Egypt on their way to Africa.

As for measures taken by the Egyptian government to deal with the grim situation, Egyptian cabinet spokesman Magdi Radi said that the country has designed a comprehensive plan in order to face the issue and a big number of Tamiflu, a kind of medicine against the bird flu disease, have already been imported.

Meanwhile, Radi asked people to stop buying alive birds to eat, recommending that it is better to change their habits and buy slaughtered birds which have been done under the supervision of the authorities.

The first bird flu case in Egypt was found in dead poultry on Feb. 17, 2006 and then the virus spread to 20 of the country's 26governorates, with the first human bird flu case in the Arab country reported on March 18, 2006.

Since then, a total of 18 reported human bird flu cases have been reported, among which 8 persons were cured.

The studies, detailed together in the Sept. 7 issue of the journal Nature, suggest the physical and mental ravages that accompany aging are not the result of simple wear and tear of the body, but of a cellular decline that is programmed into our genes—one designed to safeguard us against copying mistakes that become more frequent as we grow older.

"This research tells us why our old tissues have less regenerative capacity than young tissues," said Sean Morrison of the University of Michigan, who was involved in one of the studies. "It's not that old tissues wear out—they're actively shutting themselves down, probably to avoid turning into cancer cells."

No free lunch

Research teams from three medical schools examined the role of p16INK4a in cells collected from different parts of the body in mice.

One team, from the University of North Carolina (UNC) at Chapel Hill, looked at the gene's role in pancreatic islet cells, which produce and secrete the hormone insulin and which are defective in persons with Type 1 diabetes. Another team from the University of Michigan examined brain stem cells, while a third, from Harvard University, looked at p16INK4a in blood stem cells.

All three studies found similar results: as animals got older, p16INK4a activity increased and the cells eventually stopped dividing. Cells in mice deficient in the gene continued to divide but were more likely to turn cancerous, while cells in animals with over-expression of the gene stopped dividing earlier and aged prematurely.

The experiments also showed that cells taken from old animals remember their "age" and continue to deteriorate at their previous rate even when transplanted into young animals.

This last finding raises new questions about the usefulness of adult stem cells in tissue and organ repair compared to embryonic stem cells.

Fresh debate

The use of embryonic stem cells in medical research is currently a topic of fierce debate because harvesting the cells destroys developing embryos. As an alternative, some scientists are trying to use stem cells taken from adults and grow them into tissues in the lab; the new cells could then be reintroduced into the patient's body to replace failing tissues or organs.

"I think this data undermines that notion," said Norman Sharpless, a researcher at the University of North Carolina (UNC) at Chapel Hill who was involved in all three studies. "It shows that even these [adult] stem cells, which have the properties of self-renewal, are not limitless in their capacity to regenerate themselves. There are tumor-suppression mechanisms that limit their longevity."

Not all of the researchers agree. Morrison, the University of Michigan researcher, doesn't think the findings will have a drastic impact on how doctors use stem cells.

"I don't think this is a reason to say that embryonic stem cells are more valuable that adult stem cells," he said in a telephone interview. "It's been recognized for a long time that young adult [stem] cells are more robust than old ones. For example doctors are reluctant to do bone marrow transplants when the donor is old."

The more important consequence of the new findings, Morrison said, is that it helps explain embryonic stem cells' seemingly limitless ability to divide and become new cells.

These tumor-suppression "mechanisms probably don't exist in embryonic stem cells, and that's why they can proliferate indefinitely, while adult stem cells can't," he said.

Potential uses

The findings could prove to have numerous practical uses as well, the researchers say. For example, p16INK4a could be used as a "biomarker" to determine a cell's age. It is "like an odometer almost—you can use it to tell the mileage of the tissue," Sharpless told LiveScience.

This could allow doctors to one day do things like sort blood stem cells based on physiological age to determine whether someone will be a good bone marrow donor or not.

Also, it might be possible to create drugs that temporarily inactivate p16INK4a and promote healing in damaged cells, Morrison said.

"We could give people who have injuries a drug like that for a week or two weeks or a month," he said. "That's not likely to cause cancer, and even if some cells started to divide a little out of control during that period, you just stop the drug and p16INK4a comes back on and shuts things down again."

The findings might also lead to new kinds of therapies aimed at slowing or reversing the effects of aging, the researchers say. In the experiments, shutting down p16INK4a activity relieved only some, but not all, of the negative repercussions of aging. But scientists know of other tumor suppressor genes, and manipulating many of them at once might have a greater effect, Morrison said.

"Maybe if we look at the aggregate effects of five or six different tumor suppressors, we might be able to rescue most of the aging effect," he said.

It's Trev's place. He's worked here in the butcher's since he was 12 - about 40 years. It's a great butcher's. I'm addicted to his chipolatas. He was preparing tempting looking mixed grill packages for one of the pubs when I arrived.

I've had the carcass of one of my lambs delivered direct to Trev from judging in the national championships in Shropshire, where, to my amazement, it won National Reserve Champion.

Usually the lambs come back from the abattoir, deconstructed, in a box the size of an overnight bag. But I wanted to take a carcass whole to the butcher, partly so that I could get the shoulders boned and rolled, and partly because I wanted to watch how it all works.

It would be much more difficult to eat your own lamb if you had only one of them. After lambing, we have a couple of thousand sheep; a mixture of breeds, mainly black-faced, Texels and Belgians.

Fred, the sheep farmer, has been crossbreeding the Belgians and Texels to produce a particularly meaty "Beltex" variety - the ones that are winning prizes.

Our flock comprises half a dozen tups (rams), the remainder being ewes and lambs. The ewes give birth to either one or two young, so the numbers boom at lambing time.

The lambs skip around, looking sweet, munching grass, chasing Fred's Land Rover and falling over. They grow phenomenally quickly - ready for the table in less than a year.

I've been observing the sheep closely. They remind me of shoaling fish sometimes. Their favourite pastime is munching, which they do voraciously. Sometimes they want to come towards you, sometimes they want to run away. You can never tell which it's going to be.

They will often, but not always, follow me as I walk over the fields to the station. It's a nice feeling; a gambolling carnival escort, a huge distended, electrified shadow. I never want to go through the gate when I get there. It can be strange at night walking home when you hear them thundering along behind you and you can't see them.

At the abattoir, the innards are removed along with the head and feet. They leave the kidneys in. Lambs' kidneys are the finishing touch to the perfect English breakfast. People seem to struggle more with eating offal than the flesh cuts, but I'm a convert.

There is so little demand for heart and brain that the abattoir doesn't even give you those bits, or the sweetbreads, the pancreas. I first had sweetbreads in France last year; they're impossibly delicious, tender and tasty, the nicest bit of all. I complain about this to Trev, but he says this is the wrong time of year for sweetbreads.

The carcass has been sliced perpendicular to the spine in the centre of the back, so the fat content can be judged. Trev gets his really big saw and bisects the thing along the length of the spine, giving us two sides.

The saw is frighteningly sharp - the first of several shudderingly sharp tools - but the sawing is still physical work.

He lays the first side flat on the block and nicks the bone at the top of the back - the neck end - and invites me to saw off the first chump chop. It's pretty gruesome, but I'm glad I'm doing it myself.

Trev says that normally you don't get these two cuts, one from each side. They are part of the abattoir's commission. They do look like the meatiest lamb chops I have ever seen. "That's dinner," I say.

He saws off the shoulders and the legs, and with a long knife removes the breast and belly, which is very fatty.

I've never managed to do anything good with the breast. He advises me to cook it overnight at a low temperature. He's not wrong.

I want to keep the racks whole, for roasting, but still there are some terrifying moments with a cleaver. It goes so close to Trev's thumb.

There's a ninja quality to his work; one slip and it's all over. This deftness becomes apparent only when he lets me have a go. He bones and rolls the shoulder in about 90 seconds. It's a work of art. The shoulder looks appetising by this point. Trev reckons shoulder is the best bit, so I let him have the other one.

It's all over very quickly. We've got legs, two shoulders, two racks, some lumps for stewing, breast for slow roasting and a bunch of chump chops.

Chopping up my first lamb stayed vividly on my mind for a few days. The anatomy of a sheep is pretty similar to our own, really. I couldn't scratch my ribs without the image of that immaculate carcass springing to mind. I thought about it involuntarily as I lay in bed at night. But, boy, those chump chops were good.

I was a vegetarian for about 17 years. Now here I am, butchering and eating one of my own lambs.

It was the rooks that put an end to it. They came with the farm. We were just about to get married when we laid eyes on the place.

It suggested irresistible pastoral bliss, the full Country Life package - woods, ponds, barns, stables, river frontage. I even found the village cricket pitch on an old map. It looked like the best possible place to play out a marriage.

Through presenting BBC Radio 4's On Your Farm, I've talked to other people involved with agriculture who didn't grow up on farms, or didn't know much when they started. It seems that the decision to become a farmer is always a huge leap of faith.

Fortunately, there are people who can help when you suddenly find yourself with a farm. They're called land agents. I was lucky to find Paddy. I thought it all looked wonderfully pretty, but Paddy explained that the place was more or less a wreck.

Drainage was poor, ditches were blocked, the fences were shot, the hedges needed re-laying, the woodland was out of control. There were rampant thistles and docks.

It had been a beef farm at one time, I'm told, home to the best shorthorn dairy herd in the country. It had not been a good time for beef farmers, and the place had gradually been run into the ground.

Land must be continuously managed. Leave it, and it becomes more and more difficult to get it back into shape. When he put the farm on the market, the beef farmer sold his cattle and rented the fields to a couple of sheep farmers. A grazing let is about the lowest-risk, least-hassle arrangement for a landowner.

The sheep farmers - no one calls them shepherds any more, and they don't have dogs; they have Range Rovers - bring their own electric fences and stock. The sheep just munch everything and keep it all looking tidy.

In return for this, the tenant grazier pays about £50 an acre per year. It's not much, not quite enough to pay the accountant, but land isn't worth a lot - about £3,000 an acre. In a bank, £3,000 would earn more than twice what a sheep farmer pays, but fields are nicer to look at than bank statements. Some people spend their money on art. I guess I bought some nature.

It seemed best to stick with the arrangement that was already in place with the sheep farmers while we improved the land. As part of this process, Paddy insisted that we do something about the rooks.

There were certainly lots of them, a multitude. It's hard to tell exactly how many as they wheel and soar, spectacular and secret, high above the forest. I didn't mind them around the place.

They are a nuisance, though. Along with magpies, jackdaws, ravens and jays, rooks are members of the corvid family. They're tough and clever.

The collective noun for rooks is a parliament, and a parliament of rooks can be deafening. The sheep farmers claim they will peck out newborn lambs' eyes.

This may well not be true, but they do eat other birds' eggs, and if you "let it be", you end up with just rooks. It seemed that the reasonable thing to do was to reduce numbers, to lend a benign hand to the balance of nature, to cull them. Kill them, that is.

Killing rooks is not nice at all. There are no neat boxes for exterminating them; shotguns are the only thing that work and it's a pretty medieval and messy business, which I don't enjoy.

But I felt I was acting for the greater good. It was a hard decision for a vegetarian to make, and the moment I made that decision was the moment I became a farmer.

Farmers have to be responsible for creating a balance in nature. They've got the whole world in their hands, after all.

We really care about animals in Britain, probably more than anywhere else in the world. Still, most people can't tell the difference between a pigeon and a collared dove. It's easy - collared doves taste much nicer. Just kidding.

It is our interest in animal welfare that is leading to changes in farming methods. We're converting to full organic status. Being organic and green is no longer philanthropy; it's simply good business sense.

Sheep farming is, by its nature, quite ethical. They tend to be freerange as that's the cheapest way to raise them. They just roam over the fields. The land must be well-drained, but it's not like you have to soak the soil with chemicals to make grass grow. Sheep have a pretty organic life.

Gradually, agriculture has become a different kind of economy. We want our food to be as cheap as possible; that's the simple reason farming became more intensive.

Nowadays, farmers tend to concentrate on just one thing. There are far fewer farm workers, and the Cotswolds are peppered with beautiful but redundant farm buildings. It's very hard to make money from farming and, as cheap imports proliferate and supermarkets dominate, it's going to get more difficult.

Beef farming is no longer a viable business. We have to import beef because we don't produce enough of it here. It seems ridiculous: roast beef is our national dish - and we'll only have to rely more and more on cheap and intensively farmed imports.

Our local area has been under cultivation for millennia. There are ancient tumuli going back into the mists of time all over the parish.

We have a couple of fields of ridge and furrow, which indicates farming activity here in the Middle Ages. The oldest part of the farmhouse was probably built in the 18th century, right next to a well.

There are wells all around the barnyard. Our plot was at one time part of a vast feudal estate. In its heyday, probably around the time that the posh-ish Victorian wing was built, as well as the dairy shorthorn herd, there would have been many other things happening.

It would have been a model farm, doing a bit of everything. There would have been chickens for eggs and chickens for the table; ditto geese; pigs for curing and pigs for roasting; sheep for wool and for meat. There was a nuttery (which is now extinct) and an orchard, which still remains.

A few dozen people would have worked here, and there would have been arable crops for the livestock and for market, and cereal crops. There was a bakery - I found the traces of the huge old bread oven - and a dairy that would have produced cheese and butter.

Basically, it would have produced more or less everything you would want to find in an upmarket delicatessen in Islington, that trendy part of North London. With the right kind of farm shop on site, I think the old model farm could work again.

That's where I'd like to take things here, eventually. For now, I just have my sheep, or rather my two sheep farmers, and a cheese that's perpetually nearly ready, but we are getting there, slowly. I was talking to the builders early yesterday morning when a man rolled up in a van. He caught my eye and he returned my gaze, squarely. He was wearing a very cool hat. Somehow, I could tell he was here to do some dirty work.

Moments later, I heard a loud crack and went to investigate. He was pumping up the air pistol again, a dead sheep at his feet.

He took the pistol to another sheep's head. I found I couldn't watch. I closed my eyes at the last moment. Crack.

It was horrible. Fred said there was nothing else for it. They were suffering. I can't think of a more humane or reasonable thing to do, but it still put me off my cornflakes.

I've not been to the abattoir yet. I will, though. Everyone should, if only to buy some chump chops.

This article was first published in The Independent, December 27, 2006.

The brainchild of scientists at Cambridge biotech firm Acambis, working with Belgian researchers, the vaccine will be tested on humans for the first time in the next few months.

A similar universal flu vaccine, being developed by Swiss vaccine firm Cytos Biotechnology, could also be tested on people in 2007 - and the vaccines on the market in around five years.

Importantly, the vaccines would also be quicker and easier to make than the traditional jabs, meaning vast quantities could be stockpiled against a global outbreak of bird flu.

Martin Bachmann, of Cytos, said: "You could really stockpile it. In the case of a pandemic, that would be a huge advantage.

"If you were to start making a traditional vaccine at the start of a pandemic, there is no way there would be enough."

The Government believes a bird flu pandemic is inevitable, killing 50,000 people in Britain alone.

However, it acknowledges that the bug could be much more lethal - infecting one in two people and claiming more than 700,000 lives.

Normal winter flu can also kill, claiming up to 12,000 lives a year in the UK.

Although a vaccine exists, constant changes in the virus's appearance have until now made it impossible to create just one flu vaccine. Instead a new vaccine is put together each year to protect against the particular strains circulating at that time.

In addition, the virus used in the jab is grown in hen's eggs - a time-consuming process that yields just one shot of vaccine per egg.

The new jabs would be grown in huge vats of bacterial 'soup', with just two pints of liquid providing 10,000 doses of vaccine.

Current flu vaccines focus on two proteins on the surface of the virus. However, these constantly mutate in a bid to fool the immune system, making it impossible for vaccine manufacturers to keep up with the creation of each new strain.

The universal vaccines focus on a different protein called M2, which has barely changed during the last 100 years.

The protein is found in all types of Influenza A, including the current bird flu and the virus that caused the 1918 Spanish flu pandemic which killed up to 50 million across the globe.

Normally, such vaccines would have to go through at least five years of human tests before going on the market. However, if a bird flu pandemic occurs before that, they could be made more quickly available.

Zurich-based Cytos, which is also developing anti-smoking and obesity vaccines, has showed that its version of the jab stops mice dying from a dose of flu strong enough to kill them four-times over.

The vaccinated animals were also spared the fever that normally goes along with flu.

Although it is too early to say what the effect would be in humans, an initial course of two or three shots could provide long-lasting immunity, topped up with booster shots given every five to ten years.

Dr Ashley Birkett, of Acambis, said: "It wouldn't be that one shot protects for life but you would need fewer doses over your lifetime."

In addition, the jabs could be produced in vast quantities and stockpiled ahead of a flu pandemic - or even given to people in advance.

In contrast, a traditionally-produced vaccine, matched to the specific strain of flu, would not be available until around six months after the start of the pandemic.

The new vaccines only protect against influenza A - the version of the bug responsible for pandemic flu and the most severe cases of winter flu.

However, it may also be possible to create a similar jab against influenza B, which causes a milder form of winter flu.

Professor John Oxford, Britain's leading flu expert, said the development of a universal vaccine was the "holy grail" of flu research.

He added: "If you get a M2 vaccine which protects against the whole caboodle in the same vaccine, the possibilities are huge."

But, others cautioned that there is no guarantee that the jabs would be as effective in humans as it has been in animals.

Virologist Professor Ian Jones, of the University of Reading, said: "It is an encouraging technique which may have a role to play but it is too soon to assume that it will translate into a universal vaccine in the human population."

Dr Jim Robertson, a vaccine expert from the government-funded National Institute for Biological Standards and Control, said the main advantage of a universal jab would be lasting immunity.

"If it works, it will be lovely," he said. "The best result would be that it would last for a long, long time."

Dr Ron Cutler, an infectious diseases expert from the University of East London, said: "Continual protection would be a tremendous advantage against flu."

He cautioned however, that there is no guarantee that the M2 protein will not mutate in the future - meaning the jab will have to be regularly reformulated.