Two scientists behind a controversial H5N1 avian flu publication last
year, which deliberately modified the virus to become more transmissible to
humans (see BioNews 662), hope to perform similar experiments on a new flu strain that has
already killed more than 40 people in China.
The H7N9 flu strain had no history of infecting humans until March this
year. Since then, at least 133 people in China have been infected.
Professor Ron Fouchier from the Erasmus Medical Center in the
Netherlands, and Professor Yoshihiro Kawaoka from the University of
Wisconsin-Madison, published an open letter in the journals Nature and Science to make their case for the controversial experiments. They say
that gain-of-function (GOF) experiments are essential to mediate a potential
pandemic threat with the H7N9 strain.
Scientists often ask two basic questions when investigating specific genes:
what happens when this gene is gone, and what happens when it is extremely
active? Genetic 'knock-outs' - where a gene is silenced - are known as loss-of-function experiments. GOF
experiments seek the opposite effect, a gain in activity, resulting in over-production
of a specific protein, for example. Over-activity from GOF experiments can produce
effects in the whole organism that are considerably different to when the gene
is functioning normally.
In the case of the H7N9 strain, GOF experiments might identify the steps
needed for the flu to become airborne, where it would then pose a major threat
to public health.
A supporter of the proposal, virologist Professor Wendy Barclay from
Imperial College London, said: 'This type of work is
like fitting glasses for someone who can't see well - without the glasses the
vision is blurred and uncertain, with them you can focus on the world and deal
with it a lot more easily'.
The scientists explain that by doing these experiments they can address,
in advance, issues that might arise if such a strain naturally developed,
including resistance to treatment.
But the proposal has been criticised by some senior scientists. Marc
Lipsitch, professor of epidemiology at Harvard University told The Independent it was 'not clear how lives could be saved even if we knew the exact genetic
mechanisms governing efficient human-to-human transmission'.
Similarly, Dr Michael Osterholm, director of the Center for Infectious
Disease Research and Policy at the University of Minnesota told The Scientist: 'I
have always maintained that Yoshi Kawaoka and Ron Fouchier could do this work
safely. But my concern is that publishing their data would allow labs around
the world, which won't adhere to the same safety requirements, to do the same'.
Currently, only one case of potential human-to-human
transmission of the H7N9 strain, between father and daughter, is under