Earlier this month, the scientists who altered the H5N1 virus to create a more contagious strain that's transmissible between ferrets, agreed to a temporary moratorium, due to safety concerns. The NewsHour reported the story here and here.

That decision has, if anything, intensified the debate. What began as a question on whether scientific journals should publish the complete research has grown into an argument on whether to conduct these studies, and others like them, at all.

The Newshour asked three experts to weigh in on the matter: Richard H. Ebright, a molecular biologist at Rutgers, Vincent Racaniello, a microbiologist at Columbia, and Carl Zimmer, a journalist who has authored ten books about science, specializing in biology and evolution.

Answers have been edited for length.

What were the goals of either the Wisconsin or Dutch bird flu studies?

Zimmer: We know that sooner or later, new kinds of diseases hit our species. You just have to look at history--the way SARS appeared out of nowhere in 2003, for example. HIV crossed over from chimps to humans in the early 1900s, but no one even knew about it until the 1980s. That head start allowed HIV to become one of the most horrific killers of the twentieth century.

The only way to prepare for new outbreaks is to study dangerous viruses in the lab--and, in some cases, even make them from scratch.

There's been a lively debate about just how big of a risk H5N1 poses to humanity. It normally passes from bird to bird. When it manages to infect humans, it seems to be quite deadly. Flu viruses are continually evolving, adapting to their hosts, and yet H5N1 has not managed to spill over into our species for years now. That might mean that there are too many obstacles in the evolutionary landscape for H5N1 to reach a form that would allow it to become a human-to-human pathogen. The studies in Wisconsin and the Netherlands were designed to address that question.

Racaniello: The goal was to determine if H5N1 aerosol transmission could be achieved in ferrets in the laboratory, and if so, what mutations accompany this process. Avian H5N1 viruses do not transmit among mammals, and therefore such experiments provide invaluable insight into this process.

Ferrets were used because they are a good model for influenza virus infection. When ferret-to-ferret transmission was achieved, the amino acid changes involved can provide information on the mechanisms that regulate airborne transmission of viruses, a topic that is poorly understood. Furthermore, it makes it possible to look for these mutations in H5N1 viruses circulating in the wild, to provide an early warning of the emergence of viruses that might transmit among humans. It is important to point out that ferrets are not humans, and the viruses selected in ferrets are not likely to transmit among humans.

What are your concerns about the research?

Ebright: The primary risks are accidental release through accidental infection of a lab worker who then infects others -- for which there are many precedents -- and deliberate release by a disturbed or disgruntled lab worker, for which the 2001 US anthrax mailings provide a precedent. Bioterrorism and biowarfare also are risks.

Zimmer: I am concerned about the ad hoc way in which scientists are figuring out how to do this research. The possibility that the Wisconsin and Dutch researchers would produce mammal-ready H5N1 flu was baked into their grant applications. Surely the debate about the potential danger should have been conducted back then, rather than now, when the scientists are ready to publish their results. If scientists have to worry that they won't be able to publish their work after years of research, fewer people will address the pressing issue of dangerous new viruses.

Is there a way to safely conduct this study, or studies with similar risks, and achieve the goals of the research? If yes, how? If no, does shutting down this type of research raise concerns about scientific freedom?

Ebright: Future work with lab-generated transmissible avian influenza viruses should be performed only at the highest biosafety level, only at the highest biosecurity standard, and only after approval by, and under the oversight of, a national or international review process that identifies risks and benefits, weighs risks and benefits, mitigates risks, and manages risks.

The same should be the case for all other research directed at increasing a potential pandemic pathogen's virulence, transmissibility, or ability to evade vaccines and treatments.

Racaniello: Shutting down H5N1 transmission research is an overreaction proposed by individuals who do not understand the science or the reasons for doing the experiments.

This work can be safely conducted under Biosafety level 3* containment. Scientists have been conducting dangerous experiments for years under these conditions, and there have been no disasters. On the contrary, the only two bioterror attacks in history originated in government laboratories.

The [National Science Advisory Board for Biosecurity**] is selecting the wrong set of experiments with which to flex their regulatory muscles. There is little chance that the ferret-passaged H5N1 virus will infect and transmit among humans.

This is not the first time scientists have disagreed about conducting research in specific areas. Human genetic engineering is another example. Why has this debate been so intense?

Racaniello: Most virologists agree that the experiments should proceed and are not exceptionally dangerous. The exceptions are those who don't understand the science, and the bioterror community. These individuals have proliferated since 9/11 and the anthrax attacks. They are paid large sums of money to sit in offices and decree what scientists can or cannot do. They are not practicing scientists and they don't appear to understand the underlying science.

Entire academic departments and corporations have been funded by the U.S. government to ponder potential dangers and tell scientists what to do. We now have a bioterror-industrial complex that rivals the military-industrial complex that Dwight Eisenhower warned us about. It is a scam, and I hope one day the nature and extent of the wasted money will be revealed to the public.

Ebright: Decisions not to perform specific proposed research projects, or to perform them only after modifications to mitigate risk, are routine. However, no such mandatory review process occurs for research projects that involve the enhancement of a pathogens's virulence, transmissibility, or ability to evade countermeasures--even though such projects potentially place at risk tens, hundreds, or millions of humans.

In 2004, a National Academy of Sciences panel called for a mandatory review process to be implemented for projects that involve the enhancement of a pathogens's virulence, transmissibility, or ability to evade countermeasures. Unfortunately, the panel's recommendations were rejected by the National Science Advisory Board for Biosecurity, the panel's recommendations were not implemented by National Institutes of Health extramural research programs, and projects creating new potential pandemic pathogens were funded and performed with absolutely no risk-benefit review. We are now reaping the harvest of these poor decisions.

*Under federal law, bird flu must be investigated within a "Biosafety Level 3" lab, on a scale of 4.

*The National Science Advisory Board for Biosecurity recommended that the journals Science and Nature withhold some details of the bird flu research from publication.

From PBS NewsHour (find the original story here); reprinted with permission.