A flu drug that is effective on the newest strains of the virus has been developed by scientists from the UK, Canada and Australia.

The new drug, DFSAs, helps stop the virus from spreading by binding to the flu enzyme neuraminidase, which helps flu to spread between cells, and by binding permanently to the flu protein, blocking its action.

The current drugs on the market, Tamiflu and Relenza, only bind to the enzyme.

The research into this new drug is being conducted by scientists from the University of British Columbia in Canada, University of Bath in the UK and CSIRO Materials Science and Engineering in Australia, and is published in the journal Science and on the Science Express website.

Finding a new flu drug is a priority because experts fear that overuse of existing drugs may result in the virus building up a resistance to them.

University of Bath Pharmacy and Pharmacology lecturer Dr Andrew Watts said; "Antivirals have been very effective in stopping the spread of flu in the pandemics over the last few years; however new strains of the virus that are resistant to these drugs are emerging and represent a serious threat to our ability to effectively treat the disease.

"It is therefore vital that we develop new drugs that combat resistance. This new class of drug is based on the natural mechanism of the enzyme and so the virus can’t easily evolve to avoid its action."

This new class of drug has so far been tested in mouse models, which showed it works against both A and B influenza types and known resistant flu strains. Researchers are now doing tests on other animals.

Medical Research Council Immunity and Infections Board chair Professor Doreen Cantrell said that if the results can be replicated in clinical trials and are shown to halt infection in flu patients they have "turned a corner in the search for new antivirals that tackle the problem of resistance".

However, Dr Watts told the BBC that it would be six to seven years before the drug came to market.

The research was partly funded by the Medical Research Council through a strategic call for research into influenza.

Image: This new drug may to be more effective than Tamiflu, as it binds to the flu protein.