Should variola virus, the agent of smallpox, be destroyed?

variola virusLater this month (May 2014) the World Health Assembly will decide whether to destroy the remaining stocks of variola virus – the agent of smallpox – or to allow continued research on the virus at WHO-approved laboratories.

After the eradication of smallpox in 1980, the World Health Organization called for destruction of known remaining stocks of variola virus. The known remaining stocks of the virus are closely guarded in the United States and Russia. These consist not of a single vial of the virus, but of hundreds of different strains, many of which have not been fully characterized, nor has their genome sequence been determined.

It can be argued that there still remains a good deal of work to be done on variola virus, including development of newer diagnostic tests, and identification of additional countermeasures (antivirals and vaccines have been stockpiled in the US). Damon, Damaso, and McFadden have written a summary of the research on variola virus that should be done. We also discussed whether the remaining variola virus stocks should be destroyed on episode #284 of This Week in Virology.

We are interested in what readers of this blog think about this issue – please fill out the poll below.

Should all known remaining stocks of variola virus, agent of smallpox, be destroyed?

Ferreting out the truth on Science Sunday Hangout on Air

I joined Buddhini SamarasingheScott Lewis, Tommy Leung, and William McEwan for a discussion of the avian influenza H5N1 virus transmission experiments done in ferrets.


Going viral at Studio 360

Studio 360 with Kurt Andersen is a radio show co-produced by Public Radio International and WNYC. The show for the week of 8 March 2013 is called ‘Going Viral‘ and includes seven segments entitled ‘Viruses at the movies’, ‘Does your zombie have rabies’, and ‘Playing against the virus’. They did speak with one virologist for a segment called ‘Reconstructing viruses‘.

To record this segment of Studio 360 I traveled down to the WNYC studios on Varick Street in New York. I sat in a glass-walled, silent room with headphones and before a large microphone. I spoke with the show’s host, Kurt Andersen, who was in a studio somewhere in Los Angeles. The sound quality was excellent and our conversation was wide-ranging, including a discussion on synthetic viruses, avian influenza H5N1, dual-use research, bioterrorism, and zombies. We spoke for 30 minutes but only a bit of that ended up being released. I think that a five minute discussion of science is far less than optimal – I favor long-form science discussions which can truly inform the listener.

You can listen to my segment below or over at the Studio 360 website.

Threading the NEIDL: TWiV goes inside a BSL-4

Last fall the science show This Week in Virology teamed up with MicrobeWorld (the public outreach website by the American Society for Microbiology) and Boston University School of Medicine to produce a documentary offering a rarely seen behind-the-scenes view of a biosafety level 4 (BSL-4) laboratory. Today I am pleased to announce the release of Threading the NEDIL: TWiV goes inside a BSL-4.

Constructed in 2009 in the highly populated South End neighborhood of Boston, Massachusetts, the National Emerging Infectious Diseases Laboratories (NEIDL) facility contains labs that operate at biosafety levels 2, 3 and 4. Due to its location the NEIDL has faced a raft of legal and regulatory hurdles that have prevented BSL-3 and BSL-4 labs from becoming functional.

Threading the NEIDL is a 1-hour documentary in which Assistant Director Ron Corley along with Elke Mühlberger and Paul Duprex, virologists that will be working the facility, lead the TWiV team on a walkthrough of the BLS-4 laboratory. They explore how the NEDIL is secured from unauthorized entry, what’s like to wear a BLS-4 level safety suit, how the facility is constructed to make it safe, and how workers carry out experiments with highly dangerous viruses such as Ebola virus and Lassa virus without jeopardizing their health or that of the surrounding community.

The documentary is a never before seen look at how one of America’s state of the art biodefense research facilities operates and the security measures put in place to keep it safe, even in the heart of a major urban center.

Threading the NEIDL from microbeworld on Vimeo.

Proposed US policy on dual use research of concern

The US Office of Science and Technology Policy recently released proposed guidelines for maximizing the benefits and minimizing misuse of life sciences research. The measures establish oversight responsibilities for universities and other institutions that receive Federal funding:

Specifically, such institutions would be required to review their current life sciences research involving those pathogens or toxins deemed to be the most dangerous or most amenable to misuse, and then work with the researchers and funding agencies to develop appropriate risk mitigation plans.

This adds to a previously announced internal policy to identify DURC research and institute risk-reducing mitigation plans.

OSTP has requested comments on the proposed policy from researchers, institutions, consumers, security experts, and other stakeholders. The proposed policy can be found at this location (pdf), and instructions on how to submit comments can be found in the Federal Register.

Here is the gist of the proposal. It pertains to you if you get Federal money to work on the following organisms or toxins:

  1. Avian influenza virus (highly pathogenic)
  2. Bacillus anthracis
  3. Botulinum neurotoxin
  4. Burkholderia mallei
  5. Burkholderia pseudomallei
  6. Ebola virus
  7. Foot-and-mouth disease virus
  8. Francisella tularensis
  9. Marburg virus
  10. Reconstructed 1918 Influenza virus
  11. Rinderpest virus
  12. Toxin-producing strains of Clostridium botulinum
  13. Variola major virus
  14. Variola minor virus
  15. Yersinia pestis

And if your research might have the following consequences:

  1. Enhances the harmful consequences of the agent or toxin
  2. Disrupts immunity or the effectiveness of an immunization against the agent or toxin without clinical and/or agricultural justification
  3. Confers to the agent or toxin resistance to clinically and/or agriculturally useful prophylactic or therapeutic interventions against that agent or toxin or facilitates their ability to evade detection methodologies
  4. Increases the stability, transmissibility, or the ability to disseminate the agent or toxin
  5. Alters the host range or tropism of the agent or toxin
  6. Enhances the susceptibility of a host population to the agent or toxin
  7. Generates or reconstitutes an eradicated or extinct agent or toxin listed above

If any of this applies to you, it is necessary for you and your institution to develop and implement a risk mitigation plan which must be approved by the funding agency.

If any of this applies to you, but you do not receive Federal funds for the research, you are strongly encouraged to carry out similar oversight procedures.

Comment on H5N1 lethality in humans

In a brief letter to Biosecurity and Bioterrorism, Alan Zelicoff notes a problem with serosurveys for influenza H5N1 infection:

…peak titers after H5N1 infection occur at about 4 to 6 weeks postinfection and may drop by as much as 32-fold over the course of a year, probably decreasing the sensitivity of serologic testing for past asymptomatic infections. Micro-neutralization testing may be more sensitive.

He cites a serological survey carried out on poultry workers in South Korea, in which 9 of 2,500 subjects were found to have antibodies to H5N1 virus, in the absence of illness. These seropositive individuals carried antibodies that neutralize H5N1 virus infectivity. Assays for antibodies that block infection may be more specific for infection than hemagglutination-based assays. His conclusion:

One can anticipate additional serological surveys that will better inform public health practitioners of the threat to humans from circulating H5N1 clades….morbidity from novel influenza strains does not equate with an impending pandemic, let alone one with high mortality. It would appear likely that a systematic, prospective cohort study is in order to adequately capture the frequency of asymptomatic infection.

Human infections with influenza H5N1 virus: How many?

The lethality of avian influenza H5N1 infections in humans has been a matter of extensive debate. The >50% case fatality rate established by WHO is high, but the lethality of the virus might be lower if there are many infections accompanied by mild or no disease. One way to answer this question is to determine how many individuals carry antibodies to the virus in populations that are at risk for infection. A number of such studies have been done, and some have concluded that the results imply a low but substantial level of infection (even less than one percent of millions of people is a lot of infections). The conclusion of a new meta-analysis of H5N1 serosurveys is that most of the studies are flawed, and that the frequency of H5 infections appears to be low.

Twenty-nine different H5N1 serological studies were included in this meta-analysis. None of these are particularly satisfactory according to the authors:

None of the 29 serostudies included what we would consider to be optimal, blinded unexposed controls in their published methodologies, i.e., including in the serology runs blinded samples from individuals with essentially no chance of H5N1 infection. Serological assays can easily produce misleading results, especially when paired sera are not available.

Some of the problems identified in the serological surveys include the possibility that many H5N1 positive sera are the result of false positives, that is, cross reaction with antigens from other influenza virus strains. In addition, many studies utilized H5N1 strains that are no longer circulating.

It is clear that most of the H5N1 serosurveys have not been done as well as they should have been. The authors conclude that “it is essential that future serological studies adhere to WHO criteria and include unexposed control groups in their laboratory assays to limit the likelihood of misinterpreting false positive results.”

Let’s not forget that a completely different way of assessing H5N1 infection – by looking for virus-specific T cells – has been reported. The results provide further evidence for subclinical H5N1 infection and are not subject to the caveats noted here for antibody surveys.

I come away from this meta-analysis with an uneasy sense that the authors are not being sufficiently objective, and that they firmly believe that there are no mild or asymptomatic H5N1 infections. One reason is the authors’ use of ‘only’ to describe their findings. For example: “Of studies that used WHO criteria, only [italics mine] 4 found any seropositive results to clades/genotypes of H5N1 that are currently circulating”. The use of ‘only’ in this context implies a judgement, rather than an objective statement of fact. Furthermore, despite the authors stated problems with all H5N1 serosurveys, they nonetheless conclude that there is little evidence for asymptomatic H5N1 infection. If the studies are flawed, how can this conclusion be drawn?

My concern about the authors’ objectivity is further heightened by the fact that they are members of the Center for Biosecurity at the University of Pittsburgh. These are individuals whose job it is to find dangerous viruses that could be used as weapons. On the front page of the website for the Center for Biosecurity is a summary of the meta-analyis article which concludes that “In the article, Assessment of Serosurveys for H5N1, Eric Toner and colleagues discuss their extensive review of past studies and conclude that there is little evidence to suggest that the 60% rate is too high.”

I would argue that if the H5N1 serosurveys are flawed, then do them properly; it is incorrect to simply assume that the H5N1 virus is as lethal as WHO suggests. The World Health Organization should call for and coordinate a study that satisfies criteria established by virologists and epidemiologists for a robust analysis of human H5N1 exposure.

The risks and benefits of influenza H5N1 research

Both Nature and the New York Times have weighed in on the resumption of influenza H5N1 research. In an editorial from 23 January 2013, Nature opines that “Experiments that make deadly pathogens more dangerous demand the utmost scrutiny”:

As several critics point out, the assessments of the relative risks and benefits of such research remain restricted to largely qualitative arguments. The formal, quantitative risk assessment common in the nuclear power and other industries could have helped to nail down and quantify risks, and would have informed the debate better. One year on, an irreproachable, independent risk–benefit analysis of such research, perhaps convened by a body such as the World Health Organization (WHO), is still lacking.

The Times editors, who looked foolish in January 2012 after remarking that the H5N1 ferret transmission research should not have been done*, simply tow Nature’s line.

To clarify a point, the Fouchier and Kawaoka experiments on influenza H5N1 transmission did not make the virus more dangerous – they made it less dangerous for ferrets. How they affect the virus in humans is unknown.

I suspect that no one, not even WHO, has done a quantitative risk-benefit analysis of H5N1 research because it cannot be done. What basic research will reveal is frequently unknown – if the outcome could be predicted, then it would not be research. Scientists ask questions, and design experiments to answer them, but the results remain elusive until the experiments are done. How can the benefits be quantified if the outcome isn’t certain?

For example, one of the benefits of influenza H5N1 research is to understand what regulates aerosol transmission of the virus. It is without doubt an important question, but whether or not research will provide an answer is unknown. At best, we might identify the determinants of aerosol transmission in ferrets – but not in humans. I don’t know the solution to this problem –  should we simply assume that we will get answers to all the questions we ask? Should we conclude that H5N1 research will allow us to understand H5N1 transmission and pathogenesis, thereby leading to vaccines and antiviral drugs or novel therapies? In this case there is no doubt that the benefits of H5N1 research are very high, but I can’t put a number on it. Nature calls this a ‘qualitative’ argument. But if someone tried to make a quantitative risk-benefit analysis of H5N1 research it would be fiction.

What is the risk of influenza H5N1 virus research? Many influenza researchers feel that it is low, if work with infectious virus is carried out under the right containment conditions. Perhaps the more relevant question is what is the risk of releasing experimental results that could be used for nefarious purposes. Because H5N1 transmission experiments utilize animal models, the results cannot be directly extrapolated to humans. If a virus is isolated that transmits by aerosol among ferrets, it cannot be concluded that the same virus will transmit among humans. Also remember that gain of aerosol transmission among ferrets was accompanied by a loss of fitness – the altered virus did not cause lethal disease when transmitted by aerosol. It seems unlikely that these research findings could be used to successfully produce a biological weapon.

It seems unlikely that someone intent on producing an H5N1 biological weapon would base it on work done in ferrets, or any other animal model. Their solution would be to passage the virus in humans – an unethical experiment, but which one could imagine being done by unethical individuals. Even the outcome of this experiment would not be assured – no one knows if an H5N1 virus selected for aerosol transmission among humans would have high lethality.

I understand why the Times would ask for a cost-benefit analysis of basic scientific research – the editors are not scientists and do not understand the unpredictable nature of research. But I expected more from the science journal Nature. Have the editors who wrote this opinion forgotten how scientific research is done?

*Without having read the papers, the Times editors decided that the H5N1 ferret experiments should not have been done. When the papers were published we all learned that the modified H5N1 viruses were not lethal to ferrets.

Headline writers: Please take a virology course

Yesterday Denise Grady wrote in the New York Times about the end of the moratorium on influenza H5N1 virus research. The story headline read:

Research to resume on modified, deadlier bird flu

The Minneapolis Star Tribune reprinted Ms. Grady’s story with the following headline:

Studies will resume on deadly modified flu virus

Where do these headlines come from, outer space? The H5N1 viruses produced by Kawaoka and Fouchier, which transmit by aerosol among ferrets, are far less virulent than the parental H5N1 virus! Furthermore, the moratorium applied to all research on H5N1 virus, not just that related to these transmission experiments.

If most of the public obtains their virology information from the popular press, it is no wonder that much of the public distrusts these H5N1 experiments.

Yesterday I taught the first lecture of the 2013 version of my virology course (details forthcoming).  I told the students that one reason I want to teach virology is to enable them to understand why headlines like these are wrong.

Maybe some of my students will one day write the headlines and get them right.

End of moratorium on influenza H5N1 research

In early 2012 influenza virus researchers around the world decided to stop working on highly pathogenic avian influenza H5N1 virus. This decision came after work from the Fouchier and Kawaoka laboratories revealed the isolation of influenza H5N1 strains that can be passed among ferrets by aerosol. The moratorium on influenza H5N1 virus research has now been lifted, as described in a letter from influenza virologists to Science and Nature.

Lifting the embargo on H5N1 research is an important step forward for understanding what regulates influenza transmission. In my view it was an ill-conceived move, done to quell the growing concern over the adaptation of influenza H5N1 virus to aerosol transmission in ferrets. We now know that these viruses are not lethal for ferrets, and much of the outrage expressed about this work was misguided. In my view the moratorium has accomplished little other than delaying the conduct of important virology research.

According to the influenza virus researchers who signed on to the moratorium, its purpose was to:

…provide time to explain the public-health benefits of this work, to describe the measures in place to minimize pos- sible risks, and to enable organizations and governments around the world to review their policies (for example on biosafety, biosecurity, oversight, and communication) regarding these experiments.

An important consideration is the level of containment that will be required for studying influenza H5N1 transmission. WHO has released recommendations on risk control measures for H5N1 research, and individual countries will decided how to proceed. The US has not yet made a decision on the level of containment needed for H5N1 virus transmission research. Influenza virologists who participated in the moratorium have their own view:

We consider biosafety level 3 conditions with the considerable enhancements (BSL-3+) outlined in the referenced publications (11–13) as appropriate for this type of work, but recognize that some countries may require BSL-4 conditions in ac- cordance with applicable standards (such as Canada).

Their last statement forms the crux of the issue on H5N1 transmission research:

We fully acknowledge that this research—as with any work on infectious agents—is not without risks. However, because the risk exists in nature that an H5N1 virus capable of transmission in mammals may emerge, the benefits of this work outweigh the risks.