Sunday Times 2
Could malaria be wiped out by GM mosquitoes?
British scientists could have found the key to wiping out malaria-carrying mosquitoes – by developing a genetically modified species that produces just male offspring.
Malaria is spread by infected female mosquitoes who pass on the killer disease when they bite humans.
Genetically modified mosquitoes that almost exclusively produce male offspring could wipe out malaria. Pic courtesy Collect
But Imperial College London researchers looked to genetics to disrupt the breeding of mosquitoes so fewer females are produced, which should see mosquitoes die out within a few generations.
In lab tests they have modified mosquitoes to produce sperm that will only create males, pioneering a fresh approach to eradicating malaria.
The new genetic method distorts the sex ratio of Anopheles gambiae mosquitoes, the main transmitters of the malaria parasite.
In the first laboratory tests, the method created a fully fertile mosquito strain that produced 95 per cent male offspring, the study published in the journal Nature Communications revealed.
These were introduced to five caged wild-type mosquito populations.
In four of the five cages, this eliminated the entire population within six generations, because of the lack of females.
The hope is that if this could be replicated in the wild, this would ultimately cause the malaria-carrying mosquito population to crash.
This is the first time that scientists have been able to manipulate the sex ratios of mosquito populations.
Since the millennium increased prevention and control measures have reduced global malaria mortality rates by 42 per cent, but the disease remains a prevalent killer especially in vulnerable sub-Saharan African regions.
Malaria control has also been threatened by the spread of insecticide resistant mosquitoes and malaria parasites resistant to drugs.
Over 3.4 billion people are at risk from contracting malaria and an estimated 627,000 people die each year from the disease.
Professor Andrea Crisanti from the Department of Life Sciences said: ‘Malaria is debilitating and often fatal and we need to find new ways of tackling it. We think our innovative approach is a huge step forward.
‘For the very first time, we have been able to inhibit the production of female offspring in the laboratory and this provides a new means to eliminate the disease.’
Colleague Dr Nikolai Windbichler added: ‘What is most promising about our results is that they are self-sustaining.
‘Once modified mosquitoes are introduced, males will start to produce mainly sons, and their sons will do the same, so essentially the mosquitoes carry out the work for us.’
In this new experiment the scientists inserted a DNA cutting enzyme called I-PpoI into Anopheles gambiae mosquitoes.
In normal reproduction, half of the sperm bear the X chromosome and will produce female offspring, and the other half bear the Y chromosome and produce male offspring.
The enzyme that the researchers used works by cutting the DNA of the X chromosome during production of sperm, so that almost non functioning sperm carry the female X chromosome.
As a result the offspring of the genetically modified mosquitoes was almost exclusively male.
© Daily Mail, London