Genetic breakthrough may stop mosquitoes spreading malaria

 

Scientists have figured out a way to block the spread of malaria using genetically-modified (GM) mosquitoes that carry synthetic genes to curb the transmission of the blood parasite when the insect bites its human host.

Click HERE to upload graphic (184k jpg)

The development is seen as a potential breakthrough in preventing the spread of one of the world's most dangerous diseases. Malaria kills up to a million people a year, mostly children living in Africa where the disease is endemic, and strikes down a further 500 million victims who fall seriously ill.

A decade ago, scientists created the first GM mosquitoes but their potential use in stemming the transmission of malaria has been stymied by the theoretical inability of the engineered insects to out-compete the non-GM mosquitoes living in the wild that actually harbour the blood parasite.

However, a new study has shown that it is possible for GM mosquitoes to rapidly pass on malaria-blocking genes to wild mosquitoes with the help of a second gene that spreads the GM trait within the sperm-producing cells of male mosquitoes.

The plan is to physically attach the synthetic gene, called the homing endonuclease gene, to an anti-malaria gene and insert the entire genetic construct into male GM mosquitoes released into the wild. The endonuclease gene should then ensure that nearly all the sperm cells produced by these GM males will carry the anti-malaria trait into the next generation of mosquitoes.

Without the endonuclease gene, only half of the GM male's sperm will carry the malaria-blocking gene, as expected from the normal 50:50 ratio rule of classical Mendelian inheritance. This severely limits the ability of GM mosquitoes to outbreed and outnumber their wild cousins, whereas the endonuclease gene causes the trait to spread rapidly through the wild population of mosquitoes.

Professor Andrea Crisanti of Imperial College London said that laboratory experiments have now shown that the endonuclease gene is very effective at spreading a GM trait through a caged population of the mosquito Anopheles gambiae, one of the main malaria-transmitting species in Africa.

After introducing a few GM males into the laboratory population of mosquitoes, the GM trait increased to cover about 50 per cent of the captive mosquitoes within 12 generations of the first introduction – a period of just a few months.

"This is an exciting technological development, one which I hope will pave the way for solutions to many global health problems. It demonstrates significant potential to control these disease-carrying mosquitoes," Professor Crisanti said.

One of the advantages of using the endonuclease gene is that it can be made to be highly specific for a particular species of mosquito. An endonuclease gene designed to work in the chromosomes of A. gambiae should not affect the many other kinds of mosquito that do not carry or transmit the malaria parasite, said Professor Austin Burt of Imperial College.

"Malaria is still a terrible disease. There are around 3,500 species of mosquito in the world, but only a few of them transmit the deadly malaria parasite, plasmodium falciparum. This technology allows us to focus exclusively on controlling these most dangerous species," Professor Burt said.

Nikolai Windbichler, the lead author of the study published in the journal Nature, added: "In our mosquitoes the homing endonuclease gene is only passed on, through reproduction, directly to the carrier's offspring. This makes for a uniquely safe biological control measure that will not affect even very closely related mosquito species."

There are no immediate plans to conduct outdoor field trials in Africa with the GM mosquitoes until experiments at a large mosquito laboratory being built in Italy are carried out in the next couple of years. One of the first tasks of the scientists is to identify which of about 15 anti-malaria genes they will pick as the trait to be used in GM mosquitoes.

"The question of releasing GM mosquitoes into the environment concerns us a lot which is why we need to carry out much more research before field trials in Africa are considered in three to four years," Professor Crisanti said.

Several genetic traits have already been identified which can limit the mosquito's ability to transmit malaria. In 2002, scientists found a gene that prevents the parasite from moving from the insect's gut to its salivary glands.

A separate area of research is investigating the possibility of releasing GM sterile male mosquitoes as a way of controlling dengue disease, which is also transmitted in a mosquito bite.

Malaria in numbers

500 million new cases of malaria are reported worldwide each year.

1 million deaths are caused by malaria each year, the majority in Africa.

57 countries are registered as 'malaria-endemic', with the disease posing a threat to human life.

200,000 people die of malaria each year in India.

2 million cases of malaria were reported in Pakistan after last October's floods.

1.3 per cent rate at which malariacan decrease gross domestic product in countries with high disease rates.

765 million people in sub-Saharan Africa are said to be at risk from malaria, according to the World Health Organisation.

Start your day with The Independent, sign up for daily news emails
Voices
voices Simon Usborne: It's not about political correctness. It's about decency
Sport
Wojciech Szczesny watches the ball cross the line as Garath McCleary scores for Reading
football All the latest from Wembley as Gunners face Reading in semi-final
Life and Style
health
News
i100
ebooks
ebooksA special investigation by Andy McSmith
  • Get to the point
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Ashdown Group: Front-End UI Application Developer

£30000 - £40000 per annum + Benefits: Ashdown Group: Front-End UI Application ...

Recruitment Genius: Digital Account Executive

£18000 - £26000 per annum: Recruitment Genius: They work with major vehicle ma...

Recruitment Genius: Service Engineers - Doncaster / Hull

£27000 per annum: Recruitment Genius: Domestic Service Only Engineers are requ...

Recruitment Genius: Employability / Recruitment Adviser

£23600 - £27500 per annum: Recruitment Genius: The Employability Service withi...

Day In a Page

Where the spooks get their coffee fix: The busiest Starbucks in the US is also the most secretive

The secret CIA Starbucks

The coffee shop is deep inside the agency's forested Virginia compound
Revealed: How the Establishment closed ranks over fallout from Loch Ness Monster 'sighting'

How the Establishment closed ranks over fallout from Nessie 'sighting'

The Natural History Museum's chief scientist was dismissed for declaring he had found the monster
One million Britons using food banks, according to Trussell Trust

One million Britons using food banks

Huge surge in number of families dependent on emergency food aid
Excavation at Italian cafe to fix rising damp unearths 2,500 years of history in 3,000 amazing objects

2,500 years of history in 3,000 amazing objects

Excavation at Italian cafe to fix rising damp unearths trove
The Hubble Space Telescope's amazing journey, 25 years on

The Hubble Space Telescope's amazing journey 25 years on

The space telescope was seen as a costly flop on its first release
Did Conservative peer Lord Ashcroft quit the House of Lords to become a non-dom?

Did Lord Ashcroft quit the House of Lords to become a non-dom?

A document seen by The Independent shows that a week after he resigned from the Lords he sold 350,000 shares in an American company - netting him $11.2m
Apple's ethnic emojis are being used to make racist comments on social media

Ethnic emojis used in racist comments

They were intended to promote harmony, but have achieved the opposite
Sir Kenneth Branagh interview: 'My bones are in the theatre'

Sir Kenneth Branagh: 'My bones are in the theatre'

The actor-turned-director’s new company will stage five plays from October – including works by Shakespeare and John Osborne
The sloth is now the face (and furry body) of three big advertising campaigns

The sloth is the face of three ad campaigns

Priya Elan discovers why slow and sleepy wins the race for brands in need of a new image
How to run a restaurant: As two newbies discovered, there's more to it than good food

How to run a restaurant

As two newbies discovered, there's more to it than good food
Record Store Day: Remembering an era when buying and selling discs were labours of love

Record Store Day: The vinyl countdown

For Lois Pryce, working in a record shop was a dream job - until the bean counters ruined it
Usher, Mary J Blige and Will.i.am to give free concert as part of the Global Poverty Project

Mary J Blige and Will.i.am to give free concert

The concert in Washington is part of the Global Citizen project, which aims to encourage young people to donate to charity
10 best tote bags

Accessorise with a stylish shopper this spring: 10 best tote bags

We find carriers with room for all your essentials (and a bit more)
Paul Scholes column: I hear Manchester City are closing on Pep Guardiola for next summer – but I'd also love to see Jürgen Klopp managing in England

Paul Scholes column

I hear Manchester City are closing on Pep Guardiola for next summer – but I'd also love to see Jürgen Klopp managing in England
Jessica Ennis-Hill: 'I just want to give it my best shot'

Jessica Ennis-Hill: 'I just want to give it my best shot'

The heptathlete has gone from the toast of the nation to being a sleep-deprived mum - but she’s ready to compete again. She just doesn't know how well she'll do...