It might be possible for human-to-human airborne transmissible avian H5N1 influenza viruses to evolve in nature, new research has found.
The findings, from research led by Professor Derek Smith and Dr Colin Russell at the University of Cambridge, were published June 22 in the journal Science.
Currently, avian H5N1 influenza, also known as bird flu, can be transmitted from birds to humans, but not (or only very rarely) from human to human. However, two recent papers by Herfst, Fouchier and colleagues in Science and Imai, Kawaoka and colleagues in Nature reveal that potentially with as few as five mutations (amino acid substitutions), or four mutations plus reassortment, avian H5N1 can become airborne transmissible between mammals, and thus potentially among humans. However, until now, it was not known whether these mutations might evolve in nature.
The Cambridge researchers first analysed all of the surveillance data available on avian H5N1 influenza viruses from the last 15 years, focusing on birds and humans. They discovered that two of the five mutations seen in the experimental viruses (from the Fouchier and Kawaoka labs) had occurred in numerous existing avian flu strains. Additionally, they found that a number of the viruses had both of the mutations.
Colin Russell, Royal Society University Research Fellow at the University of Cambridge, said: “Viruses that have two of these mutations are already common in birds, meaning that there are viruses that might have to acquire only three additional mutations in a human to become airborne transmissible. The next key question is ‘is three a lot, or a little?’ “
So: was it a good idea to publish those two papers on mutating H5N1 viruses, or not? Given that as I and many other more famous people pointed out, if you don’t know what makes the viruses mammal-to-mammal transmissible, you don’t know what to look for – and now we do, and look what they found. This story will run, and run, and run – so we really, really should include an H5 consensus HA in seasonal flu vaccines!!
See on www.sciencedaily.com