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H5N1: published paper about modified avian virus

on Sun, 06/17/2012 - 16:54

At the beginning of May Nature finally published one of the two papers about the avian flu virus H5N1 that raised so many controversies inside and outside the scientific community. In this paper, the research team led by Prof. Yoshihiro Kawaoka, from the University of Wisconsin-Madison, described the creation of an artificial strain of H5N1 capable of transmission from mammals to mammals. On December 2011, the National Science Advisory Board for Biosecurity (NSABB) had expressed its negative opinion about the publication of these two papers, fearing a potential wrong use of those data but, following further discussion, both the NSABB and the World Health Organization (WHO) changed their mind, thus allowing the publication of the two studies.
The Nature paper, considered the “less dangerous” of the two announced, revealed that is not impossible for the H5N1 virus to adapt to intra-specific transmission in mammals. Bird-to-human transmission of the avian flu virus has been documented since 1987 but only very few isolated cases of suspected human-to-human transmission do exist. Some virologists seriously doubted that this virus could evolve the capability to transmit itself from human to human but now, things are changed. Kawaoka and colleagues introduced random mutations into the globular head of the viral protein responsible for the binding of the virus to the host cellular receptors – hemagglutinin (HA) – and then transferred the mutated genes into a H1N1 genetic background, which is known to be less lethal than H5N1. By doing so, they discovered two mutations that, when combined, allowed the viruses to bind to the mammal-specific receptors in vitro. Then, to test the intra-individual transmissibility of the virus in vivo, the researchers inoculated it in ferrets, which are known to be a reliable animal model for influenza virus transmissibility and pathogenesis studies. When caged together with infected ferrets, non-infected ferrets contracted the virus in a few days. Not only this study gave evidences of mammal-to-mammal transmission of the avian flu virus, but also revealed that only a few mutations are needed to confer this kind of adaptation.
It is then easy to guess why the debate about the opportunity of publishing these results has been, and still is, so intense: on the one hand, there are those like Richard Ebright of Rutgers University, New Jersey, who believes that the risks posed by the public sharing of these data – bioterrorism, accidental escape of the virus or deliberate release by a foolish lab worker – definitely overcome the potential benefits of an increased knowledge and possible practical applications; on the other hand, Stan Lemon of the University of North Carolina argues that “the risks of nature being a terrorist here are much greater than the risks of some misguided scientist” and that is better to be ready to a possible adaptation of the virus, trying to predict it happening, and counteract it.
The debate is still ongoing, waiting for the second controversial paper from Ron Fouchier’s team, from Erasmus Medical Center, Rotterdam, to be published on Science.

M. Imai et al., “Experimental adaptation of an influenza H5 HA confers respiratory droplet transmission to a reassortant H5 HA/H1N1 virus in ferrets,” Nature, doi:10.1038, 2012.