Genetically Modified Mosquitoes Could Dramatically Reduce Spread Of Malaria

Scientists working on malaria have found a way of genetically manipulating large populations of mosquitoes that could eventually dramatically reduce the spread of the deadly disease.

In a study in the journal Nature, researchers from Imperial College London and the University of Washington, Seattle found that after making specific genetic changes to a few mosquitoes and then allowing them to breed on, genetic alterations could be spread through large mosquito populations in a few generations.

This is the first successful proof-of-principle experiment of its kind, they said, and suggests the method may in future be used to spread genetic changes in wild mosquito populations to make them less able to transmit malaria.

"This is an exciting technological development, one which I hope will pave the way for solutions to many global health problems," said Andrea Crisanti of Imperial's life sciences department, who led the study.

Malaria is an infectious disease that affects more than 240 million people every year, and kills around 850,000 annually -- many of them children in Africa.

Health experts have called for malaria eradication and genetic ways of manipulating or eradicating mosquitoes have been suggested as possible alternatives to existing control methods such as pesticides and bednets. But the success of a genetic approach depends on getting the genetic modification to spread effectively in large mosquito populations.

'GENETIC DRIVE'

In these new experiments, the scientists showed that a modified genetic element -- a homing endonuclease gene called I-SceI -- can efficiently spread through caged populations of mosquitoes. The genetic element 'homes' to a particular portion of the DNA, they explained, where it becomes integrated into the broken chromosome.

This process -- known as genetic drive -- could be used to transmit a genetic change through a population of mosquitoes that affects the insects' ability to carry malaria.

Crisanti's team bred mosquitoes with a green fluorescent gene as a marker that can easily be spotted in experiments. They allowed these insects to mate with a small number of mosquitoes that carried a segment of DNA coding for an enzyme which can permanently inactivate the fluorescent gene. After each generation, they counted how many still had a green gene.

The results showed that after starting with almost 99 percent of fluorescent mosquitoes, more than half had lost their green genes in just 12 generations.

There are around 3,500 species of mosquito in the world, but only a few transmit the malaria parasite, Plasmodium falciparum. The researchers said this technique should allow scientists to focus on controlling just the most dangerous species.

"In our mosquitoes the homing endonuclease gene is only passed on... 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," said Imperial's Nikolai Windbichler, who also worked on the study.

The team is now working on targeting genes that the mosquito needs for reproduction or malaria transmission. With this technology, the release of a few modified mosquitoes could eventually cause a dramatic reduction in malaria-carrying mosquitoes in countries where the disease is endemic, they said.

By Kate Kelland
(Editing by Gareth Jones)

Copyright 2011 Thomson Reuters. Click for Restrictions.

Comments

[Lifencompass]

10:41 AM on 04/22/2011

Um GMO! Hello.

[squiems]

04:13 PM on 04/21/2011

This is something that could be done and immediately dramatically increase the standards of living for hundreds of millions of people around the world. While malaria is underreported in the western world, it still sickens hundreds of millions of people a year, kills millions, and almost everybody at risk is infected several times in their life. It is truly heartbreaking to see its effects firsthand.

[Stacy Ayiers]

12:44 PM on 04/21/2011

I hope they come up with something. In Sub Saharan Africa Malaria is still the number one killer with AIDS being the second.

Thanks for the information.

Stacy Ayiers
Green Blogger for AZ Big Media
http://aznow.biz/green/paradise-valley-gets-first-ever-leed-certified-home

[Halsey]

12:02 PM on 04/21/2011

In theory it sounds great. These scientists are, to be sure, geniuses. Yet I get chills of fear. We have no idea what long-term effects a GM bug could have. I don't want any children to die from malaria, yet we must also be prepared to FEED every child whose life we save. Isn't there something in certain African ethnicities, that sadly can cause sickel (sp?) cell but also makes the human carrier less susceptible to malaria (I may be way off here).
Brazil bread the super bee for more honey. That bee made it to the USA and destroy a lot of our friendly little honey bees. Messing with nature, simply NOT the way to go. How about TENTS and Mosquito netting for everyone and malaria shots (like any tourist to AFrica must get). I'd prefer THAT to the release of GM bugs.

[TanzaniaTeacher]

12:30 PM on 04/21/2011

Just to clarify, there is no such thing as a malaria shot. There are prophyatic medications but they must be taken continuosly and they are very expensive. Not too bad for a tourist who can afford a trip to the continent to begin with, but I lived there for a year and half as a volunteer and could only afford to buy enough to cover me for the first couple of months. Imagine trying to pay for it for your whole lifetime.

And while mosquito netting is effective while you are lying in bed sleeping, it does nothing to help you from twilight, when the mosquitos come out, until you climb into bed.

[squiems]

04:19 PM on 04/21/2011

Killer bees were developed through conventional breeding techniques, not GM. More importantly, the mere fact that humans exist in large numbers has a much larger effect on the environment than the addition of GM mosquitos. While GM gets a lot of negative press, in fact as a technique it is overwhelmingly supported by the scientific community; i.e those with knowledge of these things. And anybody who has seen the effects of malaria can tell you; any action that reduces the disease would be more than welcome. It is easy to cry that messing with nature is a bad idea, when you are in your air conditioned house in america. But right now there are millions of people in africa watching their children die and being unable to work to provide for them because of this horrible disease. Quite literally, anything would be better than the status quo, and any vague hypothetical risk is worth it to change the lives of millions of people in a positive way.

[smilidon]

11:16 AM on 04/21/2011

Experts have suggested biological solution not genetic modification. There is a huge difference between the two. When you increase the numbers of dragonflies and other naturally occurring predators of mosquitoes, then you are finding the solution biologically. This looks like a sponsored article from the company which is developing this GM mosquito and desperately wants to build public support.

[squiems]

04:23 PM on 04/21/2011

you cant just introduce the number of dragonflies. It will not work. There are far too many mosquitos and the ecosystem cannot maintain a population of foreign predators. People have been trying biological solutions to malaria for decades, and none work.

While GM is the boogeyman of the anti-science environmental movement, in actuality there is no real harm at all to using genetic modification. It is easy for a westerner who has never seen somebody suffer through malaria, or lose children to it, to say that genetic modification is bad based on some misguided environmentalist information. But in the real world, anything is worth ending the profound human suffering this disease causes to hundreds of millions of people around the world every year.

[TheBluesGuy]

05:14 PM on 04/21/2011

Anyone remember when Australia had no native rabbits? Now they're overrun with 'em. The balance of predator and prey are dependent upon the environmental conditions... usually. In this case, no native predator.

But leaving the environment alone by modifying the mosquito? That seems to be an excellent way of changing the odds in our favor, without changing the balance of nature.

[Laverita]

06:11 PM on 04/21/2011

Don't know who those experts are smilidon, but Africa's waiting for them to release that biological solution. Why haven't they? Ain't one. As for "a sponsored article from a company": does good news always have a catch? Asprin is made by companies. Does that make it bad. Geez. Give 'em a chance.