Sunday, 15 April 2012

What’s all this fuss about bird flu research?

In February the World Health Organisation (WHO) held a meeting in Geneva to discuss the fate of two papers describing the mutation of H5N1 avian influenza viruses into forms more easily transmitted between mammals. Both studies induced mutations that enabled the virus to transmit more effectively between ferrets because transmission in ferrets is believed to closely mimic human transmission. One study, led by Yoshihiro Kawaoka of the University of Wisconsin, Madison, was submitted to Nature, the other, led by Ron Fouchier of Erasmus Medical Centre in Rotterdam, went to Science

This followed the flurry of media attention caused by the US National Science Advisory Board for Biosecurity’s (NSABB) recommendation in December that the two manuscripts, “should not be published except with the deletion of experimental details and the crucial data”, due to concerns about how the research could be misused. This is known as redaction. 

The researchers involved called a 60-day pause on further experiments so the scientific community could, “clearly explain the benefits of this important research and the measures taken to minimize its possible risks”, and to allow time for international debate to take place.

Following the WHO meeting, its chair, Dr Keiji Fukuda, announced they had unanimously agreed on full publication. Regarding redaction, he said there was agreement there were issues around how to do it, which would be impossible to resolve quickly. They also decided to extend the pause on research while they work on “increasing public awareness of issues surrounding this research” and “discuss what are the best biosafety conditions for future research to be conducted under”. 

Yoshihiro Kawaoka revealed his mutations at last week's meeting
On 30th March the NSABB voted unanimously in favour of full publication of the Kawaoka paper and 12:6 in favour for the Fouchier paper after reviewing revised manuscripts.

The public debate began in earnest at a meeting held at The Royal Society last week. Kawoaka and Fouchier both spoke about their work, although Fouchier was prevented from revealing details due to Dutch export control laws. The journal editors, members of the NSABB, other flu researchers, bioethicists, public health experts and journalists also spoke and took part in lively discussion. 

So why all the Fuss?

The H5N1 threat

Renowned virologist, Prof Robert Webster, currently at St Jude Children’s Research Hospital, was first to take the podium. Speaking on epizoonosis (the transmission of disease between species), he left little doubt as to the seriousness of H5N1 evolving into a strain capable of causing a human pandemic.

Influenza is an RNA virus with 3 distinct species: A, B and C. The most virulent is A which includes sub-types responsible for the 1918 “Spanish” flu, which wiped out more than 40 million people, the less severe “swine” flu of 2009 (both H1N1), and “bird” flu (H5N1) . The H and N refer to two proteins on the virus surface thought to play important roles in its functioning. Hemagglutinin (HA) is involved in binding the virus to target cells and so is important in determining both how easily the virus spreads (transmissibility) and which species it infects (host range). Neuraminidase (NA) is involved in the release of copies from infected cells and so might be related to the virulence, or pathogenicity, of the virus. These proteins are also antigens, for which antibodies can be generated, so they tend to be targeted by antivirals and vaccines.

Influenza A evolves very rapidly. There is no proof-reading mechanism during replication, so almost every copy is a slight mutation. These constant changes accumulate, causing antigenic drift. The virus genome consists of eight separate strands of RNA (coding for 11 viral proteins), so when two different viruses enter a cell, because the genome is segmented they can reassort (swap segments), causing abrupt changes known as antigenic shift. It’s this process which is thought to enable new strains to jump species. In Webster’s words: “This is an extremely variable virus.”

H5N1 is endemic in the wild bird population of the world in low pathogenic forms, but when it gets into another species, such as chickens (it first showed up in a Hong Kong poultry market in 1997) it can evolve rapidly into a highly pathogenic form which kills all the birds within a matter of days. This form has infected humans on occasion, but doesn’t transmit well between us, and so hasn’t yet caused a pandemic; but of the 598 infections recorded so far, 59% have died. This may be an overestimate, because there may have been many milder, unrecorded, infections. But even if the case fatality rate is ten times less than this, that’s still more deadly than our best estimate of the 1918 pandemic in which it’s thought 2% of those infected, died.

One of Webster’s main concerns is the question of whether the highly pathogenic form is being perpetuated in the wild bird population. Vaccination hasn’t been an effective control strategy in the past, but culling has. So although it might still be feasible to stamp out H5N1, there is no longer sufficient political will due to how widespread infection has become, and in any case, if it’s being perpetuated in wild birds this is no longer even an option.

The aims of the research

Our current understanding of the biology of influenza is a “black hole” with little really known about what determines transmissibility. When Kawoaka, spoke, he clearly stated the aims of his research:

                “To evaluate the pandemic potential of H5N1 viruses. Can they become transmissible between mammals in respiratory droplets? What changes are necessary?” 

Knowing what changes allow the virus to spread between mammals would mean we could monitor for those changes in nature. A single mutation can mean the difference between a low pathogenic and high pathogenic avian virus, but these studies seem to suggest multiple mutations are required to increase mammalian transmissibility. Of the four mutations in Kawoaka’s reassortant virus, only one has been seen in the wild, but it seems to be common in strains that have infected humans. Fouchier said all of the mutations in the wild-type H5N1 virus created in his lab have appeared in nature, and some of them have been seen in combination. This kind of information could serve as an early warning, allowing us to either stamp out a dangerous strain, or else get a head start on vaccine production and drug stockpiling. 

But not everybody agrees about the necessity of such work. Dr Thomas Inglesby, Director of the Center for Biosecurity of the University at Pittsburgh Medical Center, and an expert in pandemic flu planning and biosecurity, argued the surveillance we have in place isn’t capable of exploiting the knowledge such research produces. Many of the countries experiencing H5N1 infections submit very few specimens so only a small fraction of infections are sequenced. He said: “Out of the millions of H5N1 infections in birds, people and other animals, only 2934 HA sequences have been submitted in the last eight years to the influenza research database.” He added: “Even when countries do submit specimens, the resulting sequence data may not be analysed or published for months or years.” He isn’t suggesting research on H5N1 shouldn’t be done, only that it should focus on strains that evolve naturally. He said “novel, engineered strains” are what concern him and given the lack of immediate practical use of this research, the risks, to his mind, outweigh the benefits. 

This issue of working with natural versus engineered strains relates to the distinction between observational and experimental methods. One of the organisers, Prof Simon Wain-Hobson, talked about “passenger mutations”, claiming: “If you don’t do experiments, you don’t have any way of finding out which [mutations] are important, which ones might be explaining why the virus might be getting transmitted more efficiently.” Experiments allow scientists to infer causation with a confidence that’s difficult to gain from observing things that have already happened.

Professor Malik Peiris, a virologist at the University of Hong Kong and director of the Centre of Influenza Research, defended the work in terms of risk-assessing animal viruses for their pandemic threat. He said: “We certainly need more surveillance, but at the same time we need a better understanding of the science to risk-assess this surveillance data. We need a better understanding of the biology of transmission.” Surveillance without understanding won’t get us very far. Regarding surveillance, he said: “It’s not ideal, but there is sufficient to make a start”. He also suggested: “If these signatures were available, that would be a strong impetus to improve and an incentive for people to increase their surveillance.”

Another problem is there are many possible evolutionary paths to transmissibility. These experiments have by no means identified all the mutations that could lead to enhanced transmissibility. Pullitzer-prize-winning journalist, Laurie Garrett, expressed concern about setting up systems based on false security. She said: “We’re going to set ourselves up for having all capacity focussed on a very narrow set of genetic possibilities and nature once again laughs at us.” But Fouchier claims they’re not interested in specific mutations as such. He said: “Clear patterns are emerging about biological traits that allow transmission. So surveillance won’t be targeted to specific mutations, but to those biological traits.”

Doug Holtzmann from the B&M Gates foundation, which part-funded Kawoaka, made a related point with relevance to vaccine development. He said although it would be “myopic” to think a specific experimental mutation is “the issue of concern” the critical question is: “Are we talking about 50, 5000 or 5 billion strains that could have the potential to cause a human pandemic? I think the fundamental experiments being explored here are meant to begin to test that hypothesis.” If it is 50 or 500 strains, he said “high yield seed strains” could be set up in readiness to “shave off a very critical three months in terms of the vaccine production process”. This is critical because it can take 6-8 months to produce a new vaccine. The 2009 pandemic demonstrated that because flu spreads so rapidly, we’re currently ill-equipped to deal with an unanticipated strain. 

What are the Risks?

There are concerns about accidental release. Ingelsby said: “If a transmissible, virulent H5N1 strain got into a human population with little or no immunity it could be catastrophic, and, as uncommon as accidents are, they do happen.”

Ron Fouchier, speaking at the Royal Society meeting last week
The experiments were conducted in labs rated as Bio-Safety Level 3 enhanced (BSL3). Kawoaka described the safety precautions involved in considerable detail. His lab is a stand-alone unit with 4 layers between the virus and the outside world, decontamination procedures, air filtering and internal and external monitoring. Researchers wear sealed suits and require FBI clearance. Fouchier said if an accident occurred in his lab “the public won’t be exposed, but the individuals in the laboratory will be”.

Some scientists have called for H5N1 experiments to be conducted in BSL4 labs, but others say this will limit the number of researchers who can work with H5N1 as these facilities are scarce. Webster said: “Please do not tie our hands by raising the biosafety level to BSL4.”

Some are worried the information in the papers could be used for bioterrorism. The chances of this seem low, for a number of reasons. The independent biosecurity assessment commissioned by Nature when they reviewed the paper stated: “There is no doubt this information could be used immediately by an exceptionally competent laboratory to provide the foundation for a programme to develop a pandemic strain of this virus.” Note the phrase: exceptionally competent laboratory. Philip Campbell, editor of Nature, emphasised: “None of this work could be done in a garage; you really do need sophisticated people and sophisticated techniques to do this work.” When you also consider there is no known way to target flu to specific populations, vaccines and anti-virals already exist, and more lethal, less haphazard pathogens already exist, this all adds up to the conclusion that there are easier, more effective ways to conduct bioterrorism.

The philosopher and bioethicist, Prof John Harris of the University of Manchester, said: “We cannot prevent bioterrorism at the cost of virus research because bioterrorism is not the only [or] even the most likely cause of bioterror.” Nature is the more likely source of threat. 

But Inglesby cautioned: 

“There’s no way to calculate the chances that this work will be replicated in the future as the result of the action of a malevolent scientist, a terrorist group, or a country. History is full of examples of how often we’ve misjudged the intentions and capabilities of others and how often science and technology has been used in ways that weren’t initially intended.” 

Well, there's no accounting for "crazies".

So what are the options?

Well, we could simply not do this kind of work, but as many speakers stressed at the meeting, this would leave us “blind” and at the mercy of nature.

The other option is to publish the work in “redacted” form, leaving out the crucial methods, thus making it difficult to replicate. There are a number of problems with this. It would hamper science as genuine researchers need the information to work effectively. Setting up a system for disseminating the full details to those who “need to know” and are judged “safe” would be tricky. What would the criteria be for deciding who gets this information? Who decides this? How do we ensure the information remains with only those people? Speaking about this, Campbell said: “Once you’ve sent a paper that’s restricted, to say, ten people in the academic community, you’ve lost any hope, in my opinion, of maintaining restricted dissemination.” 

Redaction could also lead to dangerous territory politically. If scientists in poor countries on the front line of the fight against H5N1 felt excluded, they might attempt the work themselves. It’s likely that would happen in labs below BSL3. This could mean that in attempting to deal with what Harris referred to as the “dangerous to know” problem, we end up creating a “dangerous to do” problem. But Prof Arthur Caplan, a bioethicist at the University of Pennsylvania, is worried publication could lead to a proliferation of similar work around the world, possibly in places with less developed biosafety “cultures”.

Many scientists are concerned about the effect censorship might have in discouraging bright scientists from working in the area. The biosafety assessment carried out for Nature concluded: “The majority of life scientists fear the emergence of diseases for which we have no counter measures, and pushing the best scientists towards blander areas in which they can more easily publish must increase our vulnerability to such entities.” Not everyone is convinced by this argument. Garrett pointed out that while biodefense is “the most regulated research you can imagine” it is also well funded, so although regulation far exceeds proposals for increased scrutiny of H5N1 research, scientists have not been driven away from the area. She said: “There’s been no trouble attracting people to the field, of all ages, because there’s money there.” Paul Keim, chair of the NSABB, said if funding bodies think certain work is important, but should be regulated, they have to put more money into those areas. He said the only reason any research is done on anthrax, given the “really onerous regulation”, is because a lot more money went into it. He added: “The same thing will happen here.”

Probably the most important criticism of redaction is that it probably wouldn’t achieve much. These studies didn’t invent any new methods, so anyone with the expertise and resources to replicate it could likely do so without the methods sections of the published papers. This might not always be the case, but as cyber security “guru” Bruce Schneier made clear in his presentation, the fact the work is carried out on computers, copies of the papers circulated by email during review, etc., means a determined, skilled “adversary”, would not be stopped by censorship. He said: “Any data that’s available on a computer can be hacked. Not most. Any.”

So redaction is no longer being considered. Keim explained the factors which influenced the NSABBs decision to change their recommendation. He said: “The revised papers had more clarity on risks and benefits.” It seems Fouchier’s original paper was unclear about the lethality of the mutated virus. Although ferrets that had the virus physically implanted in their trachea died, those infected by aerosol transmission didn’t. The virus was also sensitive to the antiviral Tamiflu. In fact, both viruses were non-lethal through aerosol transmission, didn't transmit as efficiently as the 2009 pandemic strain, and could be treated with existing drugs. So no killer superbugs were created here. 

Another factor was the realisation that restricted dissemination was impractical, particularly in light of national export controls, so the choice became between publishing in full, or not at all. They were also influenced by the US government’s publication, days earlier, of a new policy for regulation of what it calls Dual-Use Research of Concern (DURC), which identifies the types of experiments that warrant concern and requires assessment from the point of funding decisions onwards, rather than waiting to catch problems at the publication stage.

But this kind of work will continue, so it’s reasonable to ask whether there are any “red lines” which we shouldn’t be willing to cross. Researchers will want to know why these viruses weren’t deadly. Should experiments aiming to increase the virulence of transmissible strains be conducted? What about engineering vaccine or antiviral resistance? Inglesby said: “Are there any red lines? Let’s decide on that before proceeding.”

And where do we go from here?

Looking beyond the fate of these two papers, this is a truly global issue. That’s what pandemic means. We’re all at risk so we all need to cooperate to manage that risk. Garret gave an insightful analysis of the global politics of public health. She pointed out H5N1 is already a public health crisis in countries like Bangladesh, where millions of chickens have been culled, often without government compensation, because that’s often their primary source of protein. She said: 

“It is a perceived threat to humanity and that is why we ask of the poor people of the planet that they take the very serious measures that they take, imperilling their own economic survival, in order to control it for the rest of humanity.”

Indonesia declared “viral sovereignty” due to perceptions of conspiracy between rich nations and global organisations to “create false epidemics that would force poor countries to buy the pharmaceutical products of the wealthy world”. Egypt is currently struggling with H5N1. What would happen if the Arab world perceived a significantly different response to human infections cropping up in neighbouring Israel? How much extra risk will developing BSL3 labs in Pakistan create? Garret said: “Surveillance is politics, and if you’re not embracing the politics then you’re not going to have a solution to anything.”

Researchers need access to samples from the poor countries where H5N1 is endemic. Those nations should have access to knowledge gained from research and any resulting vaccines and drugs. Not just because Indonesia provided Fouchier’s lab with their virus, but, to quote John Harris, “because they have a need”. Gordon Duff, of Sheffield University, who co-chaired the UKs Scientific Advisory Group for Emergencies (SAGE) during the 2009 pandemic, said: “It’s a global matter – it’s about sharing resources, clinical isolates, animal isolates, results of research and products deriving from it to the benefit of all countries.” The WHO pandemic preparedness plan is based on this notion of “reciprocity”, and a number of speakers stressed the importance of sharing, cooperation, equity and trust.

We need to build more genuinely safe labs on the front line and train more scientists there in virology and biosafety. Ross Upshur of the University of Toronto said: “If global science wants to take this on, we need to make sure that we have highly trained, capable, qualified, virologists and virological labs, all around the world.”

This whole controversy has highlighted the need for this kind of research to be properly monitored and regulated. An international, independent, regulatory body needs to be constituted to do this. Upshur said: “An adequate assessment of potential social risks requires prospective review by an international body with a range of expertise, including, in this case, influenza biology and biosecurity.” How this authority should be constituted, structured and held accountable, and who should be involved, are questions still to be answered, but the scientific community needs to engage with this now if it wants to avoid excessive external regulation and government legislation.

Paul Berg of Stanford University, via videoconference link
Finally, Nobel Prize-winner Paul Berg, via videoconference link from Stanford University, spoke about the importance of building public trust “about what one knows, what one doesn’t know, and what needs to be learned”. He said: “It is important that the public should understand the nature and magnitude of the health and/or security risks and they certainly deserve to know that all means are being taken to mitigate those concerns.”

This is all going to take time, but at least the conversation has begun.

If you want to know more video coverage of the meeting is now online, or you can read more here and here.