Bird flu 'could mutate to cause deadly human pandemic'

Researchers have identified five genetic changes that could allow the virus to start a deadly pandemic, BBC News reports.

Writing in the journal Science , they say it would be theoretically possible for these changes to occur in nature.

A US agency has tried unsuccessfully to ban publication of parts of the research fearing it could be used by terrorists to create a bioweapon.

According to Prof Ron Fouchier from the Erasmus Medical Centre in the Netherlands, who led the research, publication of the work in full will give the wider scientific community the best possible chance to combat future flu pandemics.

"We hope to learn which viruses can cause pandemics and by knowing that we might be able to prevent them by enforcing strict eradication programmes," he told BBC News.

He added that his work might also speed the development of vaccines and anti-viral drugs against a lethal form of bird flu that could spread rapidly among people.

The H5N1 virus has been responsible for the deaths of tens of millions of birds and has led to hundreds of millions more being slaughtered to stop its spread.

The virus is also deadly to humans but can only be transmitted by close contact with infected birds.

Coughs and sneezes

It is for this reason that relatively few people have died of bird flu. Latest World Health Organization (WHO) figures indicate 332 people have died of the illness since 2003.

Health officials are concerned though that the H5N1 virus could one day mutate into a form that could be spread between humans through coughs and sneezes through the air.

This could, they fear, result in a lethal pandemic that could spread rapidly across the world killing tens of millions of people.

It is only now that a study has confirmed that the emergence of such a deadly virus is theoretically possible.

A group led by Prof Fouchier wanted to find out which genetic changes were required to enable the H5N1 virus to mutate into a form that could be transmitted from person to person through the air.

His team compared the genetic structure of the bird flu virus with those responsible for earlier human flu pandemics.

The researchers found five key differences, which they reasoned could be the mutations required for airborne transmission of the virus.

They confirmed their theory was correct by genetically engineering those changes into the H5N1 virus which they found could then be spread between ferrets through coughing and sneezing.

A team from Cambridge University then looked to see whether such a mutation could emerge naturally and if so its likelihood.

The researchers studied the genetic structure of 3,000 bird viruses and 400 that occur in humans.

They found some of these viruses had two of the key changes needed to become airborne. Mathematical modelling suggested it was indeed possible for a virus to develop the three further changes required during the course of an epidemic.

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