Scientists in Australia claim to have discovered what could be a life-long cure for potentially fatal allergies to peanuts, shellfish and other food.

The researchers said they had been able to “turn off” the allergic response in tests on mice using gene therapy to desensitise the body’s immune system, and suggested this could also be used to treat asthma.

They predicted human trials could begin in just five or six years.

Commenting on the study, a leading British expert said scientists had managed to cure allergies in mice before without this leading to an effective human treatment, but added that the new research could lead to the "Holy Grail" of allergy treatment.

He was sceptical about the researchers' claims their technique might be effective against asthma, but Asthma UK said it was "a very exciting step forward".

Allergies occur when the immune system over-reacts to something that is usually harmless. In the journal JCI Insight, the Australian researchers reported they had used genetic techniques to prevent this from happening in mice who were allergic to the protein in egg whites.

In a video about the new research, Professor Ray Steptoe, of Queensland University, said: “We can actually turn off the response. What that means is the disease is stopped in its tracks.

“What we do is we stop the underlying disease that causes these symptoms. That could revolutionise treatment for severe allergies. It would prevent, we think, some of the life-threatening allergic episodes that occur for people who are allergic to foods for instance.

“That would make a huge difference for people with severe allergies … what that would mean is they would no longer be in fear of life-threatening incidents if they were to go to a restaurant and be exposed to shellfish and they weren’t aware that was in the food.

“Kids with peanut allergies … could go to school without any fear of being contaminated from other kids’ food.

“We envisage in the future, with this approach, that they could go to the doctors’ rooms, get a single treatment and that would give them permanent protection from future allergic attacks or asthma attacks.”

He added that the researchers hoped human trials could begin in five to six years, estimated it would take a similar period after that for the treatment to be available to patients.

Professor Adnan Custovic, an allergy expert at Imperial College London, expressed particular caution about the claim the treatment would be effective against asthma as the condition is caused by a “completely different mechanism” to the one behind food allergies.

But he added: “This is one of the potentially exciting approaches to treating allergies.

“It’s sort of approach, where you try to switch off the allergic response, is kind of the Holy Grail, but a mouse model is not the same as a human model.

“We can cure allergies in mice but we cannot do it in humans … the mechanisms are not identical. Only time will tell whether this approach will be a viable one.”

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And he criticised the degree of optimism about the technique expressed by the Australian team.

“My real problem with this sort of bombastic statements like this is people with asthma … it gives them hope which very often is not realistic,” Professor Custovic said.

However Dr Erika Kennington, head of research at Asthma UK, was more optimistic.

“This is potentially a very exciting step forward in asthma research," she said.

"Allergen immunotherapy – exposing people to small amounts of an allergen in order to build up tolerance – is currently the only disease-altering treatment available for asthma but it can have significant side effects in some people, and every other existing asthma treatment and medication works by reducing or relieving the symptoms.

"These findings suggesting a novel approach to reversing allergic disease are therefore very welcome.

“We also know that there are certain allergy triggers that cause asthma flare ups, which makes this research important in possibly reducing the risk of life-threatening asthma attacks."

But Dr Kennington also pointed to the difference between animal and human trials.

“A lot more research is needed to see if the same results can be achieved in people before we can say that a cure for asthma is around the corner," she said.

In the study of the allergic mice, the researchers inserted a gene into blood stem cells that controls the immune response to the egg white.

The genetically modified cells were then injected into the mice’s bone marrow, where they produced new blood cells that were able to “turn off” the allergic response.

The researchers hope to create a similar form of gene therapy that works on humans after a single injection.

“We haven’t quite got it to the point where it’s as simple as getting a flu jab, so we are working on making it simpler and safer so it could be used across a wide cross-section of affected individuals,” Dr Steptoe said.

Dr Louisa James, British Society for Immunology spokesperson and an immunologist at Queen Mary University of London, said allergies were "far more complex than can be replicated in an animal model".

"Patients with severe allergies often react to several different types of allergen and symptoms can develop over several years," she said.

"Although the results are encouraging and heading in the right direction, it is too early to predict whether this form of therapy could ever be used to treat allergies in humans.

"As the authors state in their paper 'gene-therapy is not yet suitable for clinical application to mild disease in young individuals'.

"There are simply too many open questions around the translation of these findings from animal models into humans. Would the cells engineered to produce allergens produce the same response in humans? How would other immune cells that play a critical role in human allergy be affected? What are the mechanisms that ‘switch off’ the immune response and are they comparable in humans?