From: [email protected]
[mailto:[email protected]] On Behalf Of William Finseth
Sent: Monday, October 01, 2012 1:16 PM
To: CAIDC Admin
Subject: [Caidc-rccdi] New GM Frankenmisquitos
FYI
GM trials slash dengue mosquito numbers
Helen Mendes
25 September 2012 | EN | ES
Aedes aegypti mosquitoes transmit dengue fever, which kills 22,000 children
every year
Shutterstock
[CURITIBA, BRAZIL] Genetically modified (GM) mosquitoes released into the
environment,during a trial in the Cayman Islands, reduced the population of
dengue-carrying Aedes aegyptimosquitoes by 80 per cent, according to a
study.
The findings, published this month (10 September) in Nature Biotechnology,
were followed by another successful trial of GM mosquitoes in Juazeiro
region, Brazil, where a controlled release of GM A. aegypti reduced the
mosquito population in the region by 90 per cent, according to a press
release by the Brazilian science ministry issued last week (20 September).
The GM mosquitoes for the Cayman Islands trial were developed by the
UK-based biotech company Oxitec. Around 3.3 million sterile male mosquitoes,
which do not bite people and so do not spread dengue, were released in a
site in Grand Cayman, over a period of 23 weeks in 2010.
The sterile male mosquitoes mate with wild, non-GM females, and pass a gene,
inserted into GM mosquitoes by scientists, which causes their offspring to
die before reaching adulthood, thus preventing them from reproducing and
leading to a reduction in mosquito populations.
By the trial's end, scientists found an 80 per cent reduction in the number
of mosquitoes in the 16 hectare trial area, compared to untreated areas.
"It is an extremely encouraging result and the first demonstration that you
can suppress a target population through the release of engineered male
mosquitoes," Luke Alphey, Oxitec's chief scientific officer, told
SciDev.Net.
However, environmental and animal welfare group GeneWatch remains sceptical
about the effectiveness of using this method to tackle dengue.
"To achieve that level of suppression, they had to increase significantly
the number of GM mosquitoes they expected to release... That's not a very
efficient method for reducing the [naturally occurring] population," Helen
Wallace, executive director of GeneWatch UK, told SciDev.Net.
Alphey said that Oxitec calculated a ratio of GM to wild mosquitoes needed
to supress numbers, but given that it is difficult to determine the total
number of mosquitoes in an area, Oxitec had to increase the number of
released GM mosquitoes.
GeneWatch also raised concerns that the possibility of a small percentage of
GM mosquitoes surviving could pose risks to the public health, as they may
end up being more effective at transmitting other diseases, such as yellow
fever.
But Constância Ayres, a researcher from the department of entomology at
Fiocruz Pernambuco, a Brazilian research institute, believes the method is
safe.
"It is not a transgene [a transferred gene] that will remain in nature. It
sterilises offspring, so it has no role in the epidemiology of the disease.
The gene will not persist in the environment," Ayres told SciDev.Net.
However, Ayres is not confident the approach is cost-effective.
"I believe this is a promising tool, but we are a long way from using it in
nationwide control programmes. Production [of GM mosquitoes] is still a
limiting factor. I don't think it's feasible [to carry out programmes] in
big cities."
In order to scale up GM mosquito production and roll out, Oxitec has built a
new factory in Brazil. Oxitec is still waiting for the Brazilian ministry of
health to use their ideas in national control programmes, and further trials
particularly in large urban centres are required.
"This tool could be added to a well-established control programme for
instance when you need to momentarily suspend the use of insecticides, you
would have another option," said Ayres.
Alphey emphasised that the use of these GM insects in the wild has been
approved by regulatory bodies in the three countries Brazil, the Cayman
Islands and Malaysia where it has been tested.
"The persistence of genetic material in the environment is a major issue for
regulatory agencies, but different regulatory authorities have independently
concluded that there is no significant risk from this," he said.
The WHO estimates that 50 to 100 million dengue infections occur each year,
causing 500,000 cases of dengue haemorrhagic fever and 22,000 deaths, mostly
among children.
Link to article in Nature Biotechnology
Link to Brazilian science ministry's press release (in Portuguese)
REFERENCES
Nature Biotechnology doi:10.1038/nbt.2350 (2012)
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