Scientists warn the H5N1 bird flu virus could change into a form able to spread rapidly between humans.
Researchers have identified five genetic changes that could allow the virus to start a deadly pandemic.
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 said.
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.
Scientists warn the H5N1 bird flu virus could change into a form able to spread rapidly between humans
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. Ron 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 modeling suggested it was indeed possible for a virus to develop the three further changes required during the course of an epidemic.
It is the first time it has been shown that it is possible for bird flu to become airborne, but the research team was unable to determine precisely how likely this was to happen.
Prof. Derek Smith, who led the analysis, said more information was needed.
He said researchers required a better understanding of how flu viruses were transmitted between people in order to develop a clearer idea of the likelihood of the emergence of an airborne strain of bird flu.
“These are difficult things to find out,” said Prof. Derek Smith.
“What this work enables us to do is to prioritize particular experiments to obtain this information.”
It is clear though that the emergence of an airborne mutation of H5N1 is unlikely. Were it not it would have emerged already.
But researchers want to be able to calculate the risk of such a virus emerging more precisely in order to help public health officials in their contingency planning.
News of Prof. Ron Fouchier’s work, and another similar study by Yoshihiro Kawaoka published this May in the journal Nature, prompted the US National Security Advisory Board for Biotechnology (NSABB) to ask both journals last November to redact some sensitive parts of the research.
The NSABB believed the information could be used by terrorists to create a bioweapon.
The scientists who carried out the research, and the journals concerned, considered suggestions as to how the results could be redacted in the journals, but distributed to bona fide researchers who urgently needed the information.
But they concluded such a system was unworkable.
“You can’t share information with so many people in the field and keep it confidential,” according to Prof. Ron Fouchier.
Editor in chief of the journal Science, Dr. Bruce Alberts, said the publication of the research in both Science and Nature had “shone a spotlight” on the need to deal more effectively with research that could be misused by terrorists – so called “dual use research of concern” (DURC).
“It has become clear that we will need to work toward the establishment of a comprehensive, international system for assessing DURC, one that includes transparent procedures to allow selected access to any information omitted from a scientific publication to those with a need to know.”
But Prof. Ron Fouchier questioned whether a system of asking scientific journals to censor DURC work is ever workable or even appropriate.
“The general mode should be that science should be freely available so that the wider scientific community can build on the research,” he said.
“I have a hard time identifying research papers that you shouldn’t publish. So I’m not sure whether we should ever go down this alley.”
World Health Organization experts have delayed a decision on whether controversial research into the H5N1 bird flu virus should be released.
It had been looking at how the work could be released while guarding against its abuse by bioterrorists.
But talks at the World Health Organization (WHO) in Geneva decided more discussions were needed to see if it could be possible to publish in full.
One of the two journals which want to publish has already agreed to wait for talks to be complete.
The controversy is centred on two research papers – one of which was submitted to Science, the other to another leading journal, Nature, last year.
The two papers showed that the H5N1 virus could relatively easily mutate into a form that could spread rapidly among the human population.
World Health Organization experts have delayed a decision on whether controversial research into the H5N1 bird flu virus should be released
The studies prompted the US National Security Advisory Board for Biotechnology (NSABB) to ask both journals last November to redact some sensitive parts of the research, which it believed could be used by terrorists to develop such a virus.
The request caused outcry among some scientists who believed that it was an infringement of academic freedom.
Some pointed out that the scientists had given presentations about their work at conferences and the details were already widely circulated, so redaction would have little purpose.
The scientists who carried out the research, and the journals concerned, have been considering the request and listening to suggestions as to how the research results could be redacted in the scientific journals, but distributed to bona fide researchers who urgently need the information.
The information is vital to develop a vaccine to any human form of bird flu, and it would enable surveillance teams to see if the bird flu virus was mutating into a form that could be transmissible to humans.
But such efforts have been put on hold for four months as governments, scientists and the journals decide what to do.
The Geneva meeting of 22 scientists and journal representatives agreed that publishing only parts of the research would not be helpful, because they would not give the full context of a complete paper.
It agreed to extend a temporary moratorium on research using lab-modified H5N1 viruses, but also recognized that research on naturally occurring virus “must continue”.
Dr. Keji Fukada, assistant director-general of health security and environment for the WHO, said: “Given the high death rate associated with this virus – 60% of all humans who have been infected have died – all participants at the meeting emphasized the high level of concern with this flu virus in the scientific community and the need to understand it better with additional research.
“The results of this new research have made it clear that H5N1 viruses have the potential to transmit more easily between people underscoring the critical importance for continued surveillance and research with this virus.”
Dr. Keji Fukada added: “There is a preference from a public health perspective for full disclosure of the information in these two studies. However there are significant public concern surrounding this research that should first be addressed.”
Experts will now look at what information is already in the public domain and how that relates to the contents of these research papers.
A further meeting is likely to happen in a couple of months’ time.
Nature has said it is happy to wait – if there is a chance it will able to publish in full.
Science’s editor Dr. Bruce Alberts, had previously said it also wanted to publish full details of the work, unless progress was made on how to circulate details of the findings to scientists.
A Chinese man, who was the first case of bird flu in the country in more than a year, has died in the southern city of Shenzhen, according to health officials.
The 39-year-old bus driver was admitted to hospital with pneumonia but tested positive for the bird flu virus.
The H5N1 bird flu strain has a high level of mortality, killing up to 60% of humans infected with it.
Positive tests on a dead market chicken last week prompted nearby Hong Kong’s government to issue an alert.
Hong Kong authorities culled 17,000 chickens after three birds were found to have died from the H5N1 bird flu strain.
It also banned imports and the sale of live chickens for three weeks after the infected chicken carcass was found at a wholesale market.
But it was not clear whether the chicken came from a local farm or was imported.
The Shenzhen victim had not been in contact with poultry, nor travelled recently, China’s Ministry of Health told Hong Kong health authorities.
In November 2010, a 59-year-old woman was isolated in Hong Kong with bird flu but survived.
In October 2011 a 29-year-old woman confirmed to have contracted the virus died on the Indonesian island of Bali.
The World Health Organization says bird flu has killed 332 people since 2003.
The virus has been eliminated from most of the 63 countries infected at its 2006 peak, which saw 4,000 outbreaks across the globe, but remains endemic in Bangladesh, China, Egypt, India, Indonesia and Vietnam.
China’s Ministry of Agriculture warned last month that the bird flu virus seemed to exist widely in the poultry markets of mainland China, particularly in the south.
Meanwhile, the World Health Organization has expressed deep concern about the way research was being carried out on the H5N1 virus, which can be fatal if transmitted to humans.
Such work carried significant risks and must be tightly controlled, said the WHO.
Scientists in the Netherlands and the US said last week they had discovered ways in which the virus might mutate so it can spread more easily to – and between – humans and other mammals.
The US government has asked the scientists not to publish full details, in case the information is used to produce a biological weapon.