malaria

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Please Discuss: ‘Gene Drives,’ Sci-Fi Scary Or Cool Leap Forward?

Scientists say new "gene drive" technology could help fight malaria by affecting the mosquitoes that carry it. (Wikimedia Commons)

Scientists say new “gene drive” technology could help fight malaria by affecting the mosquitoes that carry it. (Wikimedia Commons)

Perhaps you’ve followed that teeny tiny controversy around genetically modified foods, the “GMO” debate. Or you watched the fierce back-and-forth over whether it was a good idea to modify a strain of avian flu in the lab to make it spread more easily, in order to study it.

If this is your kind of spectator sport, it’s time to learn about gene drives, a powerful new genetic technology that basically flips Charles Darwin on his head, allowing a sort of artificial selection to help chosen genes come to dominate in a population.

A paper just out in the journal eLife outlines a way to use gene drives to spread just about any altered gene through wild populations that use sex to reproduce. And a related paper just out in the journal Science calls for greater oversight and a public discourse about the potential risks and benefits of gene drive technology — now, while it’s still in early stages and confined to labs.

I can already imagine the “pro” side of the debate: “This could eradicate malaria. Reduce the use of pesticides. Bolster agriculture for a crowded planet.” And the “con” side: “But what if it goes wrong out in the wild? Have you read no science fiction?”

I spoke with two of the paper’s co-authors: Kevin Esvelt, a technology development fellow at the Wyss Institute for Biologically Inspired Engineering and Harvard Medical School, who is also the lead author of the eLife paper; and Kenneth Oye, Professor in Engineering Systems and Political Science at MIT and director of policy and practices of the National Science Foundation’s Synthetic Biology Engineering Research Center. Our conversation, edited:

CG: So what exactly is a gene drive and why are we talking about it now?

Kevin Esvelt: A gene drive is a potential new technology that may let us alter the traits of wild populations but only over many generations. We think that gene drives have the potential to fix a lot of the problems that we’re currently facing, and that natural ecosystems are facing, because it allows us to alter wild populations in a way that we could never do before.

We would really like to start a public conversation about how we can develop it and use it responsibly, because we all depend on healthy ecosystems and share a responsibility to pass them on to future generations.

So how do they work? The reason we haven’t been able to alter wild populations to date is natural selection. When you say natural selection, you think, ‘How many organisms survive and reproduce?’ And that’s pretty much how it works. The more likely you are to survive and reproduce, then the more copies of your genes there are going to be. So genes that help an organism reproduce more often are going to be favored.

The problem is, when we want to alter a species, the way we want to alter it usually doesn’t help it survive and reproduce in nature. But that’s not the only way that a gene can reproduce. We have two copies of each gene, and when organisms have children, each of the offspring has a 50% chance of getting either copy. But you can imagine that a gene could gain an advantage if it could stack the deck — if it could ensure that it, rather than the alternate version, was inherited 70%, 80%, 90%, or 99% of the time.

How gene drives affect which genes are passed down (Courtesy Kevin Esvelt)

How gene drives affect which genes are passed down (Courtesy Kevin Esvelt)

There are a lot of genes in nature that do exactly this; they’ve figured out an incredible variety of ways of doing that. Almost every species in nature has what we would call an ‘inheritance-biasing gene drive’ somewhere in its genome, or at the very least the broken remnants of one. They’re actually all over the place in nature.

The idea that we could harness these to spread our alterations through populations has actually been around for a long time. Continue reading

Mosquito Bites For Malaria Protection

A mosquito bite for your health?

NPR’s Joanne Silberner reports on the long term-effectiveness of a mosquito bite “vaccine” as a weapon against malaria, which kills about 780,000 people a year, mostly children in sub-Saharan Africa.

Since a true vaccine has been elusive, Silberner reports, Dutch researchers have been pursuing a new approach: “vaccinating” people by having them get bitten by mosquitoes carrying the malaria parasite, which is similar to how people get infected in the real world. And it seems that this technique may keep people safe from the disease more than two years later.”

In the Dutch experiment, 10 volunteers were bitten multiple times by malarious mosquitoes. The researchers then gave the volunteers an anti-malaria drug, chloroquine. (And yes, the researchers were very careful to pick a malaria type that can be vanquished by chloroquine, not a variety resistant to the drug.)

A couple of years ago, the researchers reported that this process works in the short run to protect against malaria. But that’s not such a big deal. People naturally infected by malaria build up an immunity that holds for several months.

What’s new is that the researchers went back to six of the volunteers 28 months later. Once again the volunteers allowed themselves to be bitten by malarious mosquitoes. Four of the six did not get infected. And the immune systems of the remaining two put up a fight – their infections were delayed (and quickly treated). The results were published online in The Lancet.