"This study, from what I can tell, may be the most worrisome and controversial biological dual-use research that has occurred," said Michael Selgelid, the deputy director of the Centre for Human Bioethics at Monash University. The study, led by virologist Ron Fouchier of the Erasmus medical centre in the Netherlands, was first outlined at an influenza conference in September, but is yet to be published in a journal - the next step for an academic. Dr Fouchier and his colleagues are waiting for a review of the study by the National Security Advisory Board on Biosecurity (NSABB), a US body that issues non-binding decisions on live sciences research. The NSABB's next meeting is on December 15, but even if it recommends the study not be published - and the decision is supported by the US government, the scientists could still publish their work in non-US journals, or on the internet, Dr Selgelid said. Sensitive research

The H5N1 virus previously affected only birds, but in 1997, it was found in humans in Asia. The flu spread across the world, infecting almost 600 people, according to the latest data from the World Health Organisation (WHO). The virus was not known to have, or had not, mutated to the point at which it could be transmitted between humans until Dr Fouchier and his team embarked on their research. Using ferrets, which react to viruses in a similar way to humans, the scientists tested out mutations of the bird flu. Through five mutations, they created a strain of the H5N1 that was airborne, killing ferrets kept in different cages, the New Scientist magazine quoted Dr Fouchier as saying.

"It is worth asking the question - have the scientists pre-empted a naturally occurring threat, or have they simply created a threat that would not - and might never - otherwise exist?" asked biosecurity expert Christian Enemark of the Australian National University (ANU). Associate Professor Enemark said that, while it was not possible to measure the likelihood that such research could be used as a bio-weapon, "before this virus was created, however, there was no such chance". Even if the virus was not used for nefarious purposes, it could accidentally be released from a laboratory and cause a health crisis, Dr Selgelid added. How devastating could it be? The 1918 Spanish flu is considered to have been the "most severe" influenza pandemic, killing between 20 and 40 million people, the WHO said.

But the airborne disease had a mortality rate of about 2.5 per cent, compared with the H5N1 virus, which has a mortality rate of about 60 per cent. "The study's [mutated] virus seems to be as deadly even when it became easily transmissible between ferrets," Dr Selgelid said. "It seems not unlikely that the same changes would lead to a contagious human flu virus with a very high mortality rate." The recently released Hollywood film Contagion depicts the sudden outbreak of a similarly virulent disease. Both the virus - and the fear surrounding its deadly impact - spread like wildfire, infecting hundreds of thousands of people, as medical authorities struggled to find a vaccine. But should science be censored?

Associate Professor Enemark and Dr Selgelid said the justifications for publishing the H5N1 study depended on whether the public health benefits of releasing it outweighed the risks. Dr Selgelid said that, while supporters of the study believed it would help scientists monitor and understand further mutations of the bird flu, there were many other ways the virus could evolve. "More importantly, even if we see it coming, in reality, there is not much we can do about it. One of the important lessons learnt from the H1N1 flu [swine flu] epidemic is that it's really hard to contain pandemics of flu," he said. "So those benefits seem limited." Associate Professor Enemark, who specialises in the security impact of infectious diseases, said he saw "very little" of such types of sensitive data published.

Even if they existed, "it never sees the light of day", he said. "I would oppose publication, not because it would make a huge practical difference in an immediate sense, but mostly because it would send a strong signal to research scientists that it is not just their opinions that matter. "In this particular case, the risk-benefit calculus is arguably so finely balanced, and the stakes potentially so high, that there needs to be broader input on research and publication decisions from non-scientist policymakers, ethicists, and so on," he said. But what about the scientific ideal of freely sharing information and ideas? Shouldn't scientists refuse censorship by governments? Dr Selgelid said censorship should occur only in exceptional cases, but that precedents have already existed for decades in the nuclear industry.

"In nuclear physics, discoveries with weapons implications are automatically born classified in the United States whether or not the research is funded by governments." To ensure that any such censorship is justified and verified, an international body similar to the NSABB and under the auspices of the WHO could be set up, with a panel of experts in both the science and security fields examining research that could lead to potentially severe impacts on public health, Dr Selgelid said. The body should also have the power to impose binding decisions under international law, he added. "This study reveals that biological sciences are now in a situation similar to that of atomic physics at the time when key discoveries were made that enabled the production of the first atomic weapons," he said. "This is a key moment in the history of biology."

Other controversial studies in the past decade * 2001 - Scientists from the CSIRO and the ANU were working on developing a contagious contraception for mice to make them infertile - using a mousepox virus. But what they discovered was a vaccine-resistant strain of mousepox. As mousepox is closely related to smallpox - one of the worst diseases in human history and at the top of feared biological agents - there were fears it could be used as a bio-weapon, Dr Selgelid said. The study was published, along with the description of materials and methods used, he said. * 2002 - Scientists from the State University of New York in Stony Brook, who were funded by the US's Department of Defence, synthesised the polio virus from scratch, using information published on the internet. They bought strains of DNA via mail order, stitched them together and created the synthesised polio genome. They then mixed it in a "cell juice" solution that gave birth to a live polio virus that killed mice that were injected with it, Dr Selgelid said. The study and its methods were also published.

Dr Eckard Wimmer, the lead scientist on the project, warned: "The world had better be prepared. This shows you can re-create a virus from written information." * 2005 - Scientists from the US's Centres for Disease Control and Prevention (CDC) reconstructed the Spanish flu virus, using the remains of a victim buried in the permafrost in Alaska in 1918. They sequenced the flu's genome before reconstructing the virus using methods similarly those used in the polio study. Loading Scientific observers said then that terrorists were not likely to have the capabilities to carry out similar reconstructions. "These are not easy viruses to reconstruct," Professor Diane Griffin of Johns Hopkins University's Bloomberg School of Public Health said in 2005. "You're not going to do this in a cave in Afghanistan." Follow this reporter on Twitter @curious_scribe

