‘Lab-created H5N1 viruses removed natural barriers’

Both teams avoided the use of pigs that allow influenza virus strains to mix

LIMITATION: One team was able to produce an aerosol-transmissible strain only when H5 was combined with H1N1 pandemic strain.

In two articles published today (February 2) in Nature , members of the United States National Science Advisory Board for Biosecurity (NSABB) have for the first time gone on record explaining the reasons behind their decision to “recommend” both Science and Nature to publish only the redacted (censored) versions of two studies on H5N1 influenza virus created in the labs. The Board fears that the information can be misused by some if published in full.

In an interview to Nature , the acting NSABB chair Paul S. Keim explains the several reasons behind the board's decision.

Yoshihiro Kawaoka of the University of Wisconsin-Madison and his colleagues succeeded in producing a mutant H5N1 influenza virus that had the ability to become transmissible by air. The mutant virus was created by combining H5 haemagglutin with genes from the 2009 pandemic H1N1 influenza virus.

However, the team was unable to produce a mutant H5N1 virus that could become transmissible by air without combining H5 with H1N1 pandemic strain. So why did NSABB still decide to recommend only a censored version to be published in

Nature ? “They provide a method for producing a transmissible H5N1 virus,” Dr. Keim states. “They demonstrate the compatibility of segments of the 2009 pandemic influenza backbone with H5 haemagglutinin to produce a virus that can be transmitted between ferrets [the best animal models that mimic human influenza effects].”

Moreover, the detection in humans last year of a novel H3N2 virus that had reassorted (mixed) in pigs had a great influence in their decision. In nature, pigs act like mixing vessels where various influenza virus strains combine with each to produce a strain that proves to be pathogenic and/or transmissible by air.

Compared to the mutant H5N1 virus created by Ron Fouchier of the Erasmus Medical Centre in Rotterdam (the other team that created a mutant H5N1 virus), the one created by Dr. Kawaoka also lacked virulence. Yet, NSABB decided not to clear it for full-paper submission.

“The artificial evolution of a new mammal-adapted H5N1 virus, as reported in these two papers, has removed the natural barriers that might have existed,” Dr. Keim explains.

Dr. Fouchier went about creating the mutant virus by first inserting three mutations in the lab and then passing the virus from one infected ferret to another till it became transmissible by air.

Dr. Kawaoka had also used ferrets. Hence both the teams avoided the use of pigs for the virus to reassort (mix) into transmissible and virulent forms.

Dr. Keim goes further to explain the rationale for requesting the journals to censor the papers. “The laboratory created virus has bypassed the apparent barriers to evolution in the wild,” he notes.