Controversial research showing how the H5N1 'bird flu' virus can be altered to make it transmissible between mammals through the air has been published, nine months after it was first presented at a conference.
Two different research teams have identified a number of mutations that are required to change the H5N1 virus strain found in nature into one that can be transmitted airborne between mammals. These mutations, which alter the physical traits of the H5N1 virus, could potentially cause a deadly flu pandemic.
One team, led by Professor Ron Fouchier from the Erasmus Medical Centre in the Netherlands, artificially engineered the virus to be able to infect the upper airways of ferrets. They then allowed the virus to undergo its natural life cycle before artificially transferring it to another ferret. After several transfers the virus evolved the ability to be transmitted between ferrets through coughs and sneezes. The second team, led by Professor Yoshihiro Kawaoka at the University of Wisconsin-Madison in the USA, combined the H5N1 virus with the highly transmissible H1N1 flu strain to produce a similar result.
Identification of these traits is useful, as scientists can now look out for them arising in the wild H5N1 virus. 'Now we know what changes in the behaviour of the virus can make it transmissible, we can watch for any mutations with those effects - not just our particular ones', says Professor Fouchier. 'In principle, H5N1 can become airborne. The critical question is whether it will'.
Another research group, led by Professor Derek Smith at the University of Cambridge, has sought to answer this question. The researchers sequenced a large number of wild H5N1 genomes and found that many were only two to four mutations away from the ones identified by Professors Fouchier and Kawaoka. However it is still not known whether different combinations of mutations will result in airborne H5N1. If it were likely for H5N1 naturally acquire the traits to become airborne, it would have done so already, commentators point out.
Fears that the research could have negative consequences, either through insufficient containment allowing the virus to escape from the laboratory, or use of the knowledge to produce a bioterrorist weapon, had led the US Government's National Science Advisory Board for Biosecurity to block publication of the results. However scientists have successfully argued the benefit of publication outweighed this. Disclosure of the research would aid development of a vaccine and public health strategies to prevent spread of a transmissible H5N1 virus, they said.
Scientists are keen to carry out further work looking into how deadly the transmissible virus might be, with the results in ferrets suggesting reduction in deadliness when the virus became transmissible. However there is now a moratorium on research into boosting H5N1 virulence and transmission, and this could spark a wider debate on policy towards 'dual-use research' that can have both positive and negative consequences.