Revolutionary drug which both prevents and treats illness 'more effective than Tamiflu'

February 6, 2016  13:47

A revolutionary new drug that could both prevent and treat flu has been developed. The treatment - which scientists hail as more effective than Tamiflu - was effective at fighting different strands of the virus.

A major problem with the current flu jab is that flu viruses evolve and and mutate rapidly, with new strains continuously emerging.

But now scientists, who tested the drug on mice, are confident they have created an effective treatment which works against a range of strains of the virus.

They are hopeful the new drug will work just as well in humans - offering hope of wiping out future epidemics and protecting infants, the elderly and people with weak immune system. The study on mice involved infecting them with a normally fatal dose of the bug.

Those which had been injected with medication survived without losing any weight while the others wasted away and died.

The designer drug, called HB36.6, works by binding to influenza proteins known as hemagglutinin (HA) and neuraminidase (NA).

In the study, rodents were given a single dose through the nose and then injected them with the 2009 H1N1 pandemic flu virus, which killed up to half a million people, mainly in Asia.

Those given the earliest treatment, two days in advance, were completely protected, failing to develop any symptoms whatsoever.

All of the treated animals lived and had little weight loss, whereas all untreated controls died after losing a third of their body weight or more.

The nasal injection was also able to protect mice after they had been exposed to flu, when administered either as a single dose within a day, or when it was given daily for four days starting 24 hours after infection.

The drug even worked when the host immune response was low.

When the researchers repeated experiments in two mouse strains genetically engineered to have deficient immune systems, HB36.6 protected them as well.

A single dose of HB36.6 was also more effective than ten doses of Tamiflu, also known as oseltamivir, given twice daily for five days.

Furthermore, when they gave the mice a small amount after infection, which by itself was not able to afford full protection, together with twice daily doses of Tamiflu, all the mice survived, indicating an enhanced effect when the two antiviral drugs are combined.

Professor Deborah Fuller, of the University of Washington, Seattle, said the results 'show computationally designed proteins have potent anti-viral efficacy in vivo (a living organism) and suggests promise for development of a new class of HA stem-targeted antivirals for both therapeutic and prophylactic (preventive) protection against seasonal and emerging strains of influenza.'

The study published in PLOS Pathogens said under the microscope flu viruses look a bit like balls covered with spikes which are actually the proteins HA and NA, both consisting of an inner stem region and a highly variable outer blob.

The individual variants fall into designated groups, and this is how flu strains are categorised, such as H1N1 which caused global devastation.

Ongoing mutations that change the HA and NA blobs are the reason why flu vaccines differ from season to season.

Experts try to predict which strains of the virus are most likely to be prevalent in the coming year. 

And dangerous pandemic strains often have radically new blobs against which existing immunity is limited.

In the search for drugs that act broadly against different flu strains, researchers had previously shown antibodies against the HA stem region can prevent infection.

They activate the host immune response which then destroys the bug. This approach depends on a fully functional immune system which is not present in infants, the elderly, or immune-compromised individuals.

In the latest study, Professors Deborah Fuller and David Baker from the University of Washington in Seattle, set out to develop small molecules that, like the protective antibodies, bind to the HA stem.

They then tested whether these small molecules could protect against influenza infection.

Designed to mimic antibodies, the small molecules bind the virus in a similar manner.

However, because they don't engage the immune system the way antibodies do and - because of questions of stability and potency - it was not clear whether they would be able to prevent infection in animals.

It led researchers to optimise their favourite small molecule candidate by systematically generating thousands of versions and testing how tightly they bound HA stems from seven different flu strains.

After its success on mice, the ultimate test in the future will be on humans.

Each year, flu epidemics kill around half a million people worldwide as increasingly severe forms evolve.

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