Constant readers may have noticed that after a lull of a couple of years, interest and concern over the H5N1 bird flu appears to be on the rise again.
Last month, In H5N1: An Increasingly Complex Family Tree, we looked at the continued diversification of the H5N1 virus, which has now evolved into at least least 20 genetically separate clades of the virus, with many minor variants of each clade thrown in the mix.
Last August, in Professor Peter Doherty On Bird Flu, we looked at his concerns over the possibility that the H5N1 virus might one day swap genes (reassort) with the H1N1 virus and produce an easily transmitted, highly virulent flu strain.
Reassorted viruses can result when two different flu strains inhabit the same host (human or otherwise) at the same time. Under the right conditions, they can swap one or more gene segments and produce a hybrid virus.
In September of this year Professor John Oxford - Scientific Director of Retroscreen Virology Ltd. and a Professor of Virology, expressed renewed concerns over the continued evolution of the H5N1 bird flu virus during a Webinar: John Oxford On Pandemic Preparedness.
But while nature continues to play mix and match with influenza genes – looking for a more `biologically fit’ combination - so do scientists in the laboratory.
Using reverse genetics, scientists are creating influenza reassortments to see exactly what genetic changes are needed to turn H5N1 (and other flu strains) into a human pandemic threat.
A few recent examples of this kind of research include:
In Study: Reassorted H1N1-H5N1 Produced Virulent Strain, we looked at work conducted by researchers at St. Jude Children’s Research Hospital who created several reassortant 2009 pH1N1 viruses with individual genes borrowed from a 1997 H5N1 virus.
They found that one of these lab-created viruses, with the HA gene from the H5 virus, increased replication over the parental strain and produced virulence in mice comparable to the parent H5N1 strain.
And last February in PNAS: Reassortment Of H1N1 And H9N2 Avian viruses we saw research from Chinese scientists that created – using reverse genetics – 128 reassorted viruses from the avian H9N2 virus and the (formerly pandemic) H1N1 virus.
In mouse testing, they found half of the hybrid viruses were biologically `fit’ as far as replication goes, and 8 hybrids were significantly more pathogenic than either of their parental viruses.
Most strikingly, last September we learned of as-yet unpublished research conducted by Ron Fouchier of the Erasmus Medical Center in the Netherlands.
He basically `mutated the hell’ out of the H5N1 virus in the lab, and then passed it serially through 10 ferrets, during which time it mutated further to become both easily transmissible and highly virulent.
You can read about this work in Katherine Harmon’s Sci-Am article.
I wrote a follow up to this story in New Scientist: Five Easy Mutations.
These studies have evoked considerable controversy over what kinds of information should be published, since the details of these sorts of experiments could conceivably be used to create a bio-weapon.
Today NPR has a segment on their Morning Edition show that looks at the ethics of such research and their publication.
You can listen to the 5 minute audio report at the link below.
November 17, 2011
November 17, 2011
Scientists are worried about the deadly bird flu called H5N1 which sometimes infects people. It's never acquired the ability to transmit easily between humans, but researchers would like to know if that could happen. Recently, they've essentially been altering the genes of H5N1 to make the virus spread more easily between lab animals — raising concerns about biosafety and how this research is regulated.