Canada this month announced that any research on mammalian-transmissible strains of the H5N1 avian flu virus in the country’s labs would need to be done at the strictest level of biocontainment, biosafety level 4 (BSL-4). It’s the first country to issue a biosafety rating following the creation of such H5N1 strains in two recent controversial studies (see Nature News Special: Mutant Flu).
The question of which biosafety rating is appropriate for research on the new strains was highlighted as crucial by an expert meeting convened in Geneva last week by the World Health Organization (WHO). The new, modified H5N1 strains are held at Erasmus Medical Center in Rotterdam, the Netherlands, and at the University of Wisconsin-Madison, in two BSL-3-enhanced facilities (the second highest biocontainment level), and the WHO described these as “well-established research facilities with high security and high safety“. But it also recommended that regulators “urgently” review the biosafety and biosecurity conditions under which further research on such strains is conducted, and that until that’s done, the strains should stay where they are and not be shared with other labs.
In biosafety assessment, pathogens are classified in terms of their ‘risk group’ (RG) on a scale of 1–4, where 4 is the highest, on the basis of an assessment of the relative threat they pose to people. They are also classified in terms of the biological containment levels needed, again on a scale of 1–4. What can be a bit confusing is that although required biocontainment levels for various research on a pathogen largely mirror the risk-group rating, they don’t necessarily equate with it. Some types of research may be permitted at a lower biocontainment level than their risk group, if it’s assessed that the research can be done safely with less-restrictive precautions. As the WHO explains, biocontainment level designations are “based on a composite of the design features, construction, containment facilities, equipment, practices and operational procedures required for working with agents from the various risk groups”.
Barry Bloom, a researcher and former dean at the Harvard School of Public Health in Boston, Massachusetts, also emphasizes the importance of training. “Security in handling dangerous pathogens is, in my view, less a function of the physical containment facilities than the training, experience and competence of the scientists working with them,” he says.
Some flu researchers are concerned that work on mammalian-transmissible H5N1 viruses will be severely hampered if it is restricted to BSL-4 laboratories, because BSL-4 conditions are much more constraining than BSL-3 labs, and because there are only a few dozen BSL-4 labs worldwide. Other experts feel that such high containment is essential, given the risk that any escape of the viruses could cause a H5N1 pandemic (see Fears grow over lab-bred flu.)
Whatever biocontainment levels are eventually decided as appropriate by the relevant authorities, many researchers are concerned about the proliferation of such mammalian-transmissible avian flu strains: as more labs work on them, the risk of release — accidental or intentional — goes up. Bloom says that he hopes that the number of labs allowed to work on them “would be limited, transparently identified, and monitored for safety under the aegis of an international body such as WHO”.
Declan Butler asked Sandra Fry, director-general of the Public Health Agency of Canada’s Pathogen Regulation Directorate, and Marianne Heisz, head of the directorate’s Office of Biosafety Programs and Planning, how the agency reached its decision to classify work on the new lab strains as requiring BSL-4 (note that Canada uses the term ‘CL’ in place of BSL) facilities.Read the Q&A under the fold.
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