PBS高端访谈：How CRISPR gene editing puts scientists in the driver's seat of evolution
JUDY WOODRUFF: As Vice President Biden said earlier, innovations in genetics could be crucial to finding cures for diseases like cancer.
One of the most significant developments in this field is the newly discovered ability to modify the very genes in our DNA. The technique is known by the acronym CRISPR.
William Brangham has our conversation.
WILLIAM BRANGHAM: CRISPR is a technique that allows scientists to go into the DNA of a plant or an animal or even a human being and remove or replace a small part of that organism’s genetic code.
This technique, which can be used to improve crops, eliminate genetic diseases, or specifically target the viruses and pathogens that have killed billion, could be a revolutionary advancement.
The potential for CRISPR is described in the recent issue of The New Yorker. The story is called “Rewriting the Code of Life.”
And I’m joined now by its author, New Yorker staff writer Michael Specter. He joins me from California.
Michael Specter, welcome.
In your story, you profile a young scientist named Kevin Esvelt. And I want to quote a line from your story. You say that Esvelt directs the — quote — “sculpting evolution group at MIT, where he and his colleagues are attempting to design molecular tools capable of fundamentally altering the natural world.”
I mean, that’s a pretty extraordinary set of ambitions. What are they trying to do?
MICHAEL SPECTER, The New Yorker: You know, they’re trying to look out the problems we have in health, in crops in a variety of ways, and rewrite DNA, which is the basic code of life, so that it can make us healthier, safer, protect crops, protect trees, protect endangered species.
It’s a tremendously energetic and ambitious idea. And it has — like all wonderfully ambitious ideas, it has great risks, too.
WILLIAM BRANGHAM: You report on a particular experiment they’re running up in Nantucket trying to target Lyme disease.
Can you explain what they’re hoping to do there?
MICHAEL SPECTER: Mostly, people think about Lyme disease in deer. And there is a relationship.
But the real reservoir for Lyme is the white-footed mouse. At Kevin Esvelt at MIT said, gee, let’s rewrite the DNA of the mouse so that it is resistant to the Lyme tick, so when a Lyme tick bites it, it doesn’t matter.
And when you do that, you sort of break this chain of transmission between mice and deer and humans. And if you did that enough, and if you really rewrote the DNA — mice are not that rapid, but they’re relatively rapid at reproducing — and you can quite easily see a way in which you would get rid of that disease.
WILLIAM BRANGHAM: I mean, as you describe it in this piece, CRISPR is really putting us in the driver’s seat for evolution, and not only to control, in some ways, evolution, but to accelerate evolution.
Am I understanding that this just seems to be a tremendously — tremendous potential for this?
MICHAEL SPECTER: I think the particularly revolutionary thing here is the combination of CRISPR, which is an editing program — it’s like editing something on your computer so that you can cut and paste words — combining that with this phenomenon called gene drive.
WILLIAM BRANGHAM: Gene drive? And gene drive…
MICHAEL SPECTER: Yes.
Gene drive is something that scientists have known about for a long time. We all are supposed to get one copy of a gene from each of our parents. And that’s usually what happens. That’s Mendelian genetics.
But every once in a while, there’s something called a selfless gene. A gene figures out a way to be tricky, to be counterfeit, to cram itself in where it ought not be.
And a guy named Austin Burt, who teaches at Imperial College in London, figured this out sometime ago. And he basically said, gee, if we could use those selfish elements the way we wanted, we could interrupt some things. We could make malarial mosquitoes unable to carry malaria.
And he named a bunch of things like that. But it was theoretical then, because they didn’t have this fantastic tool. Now you have the tool and you have this phenomenon. And when you put them together, you can really envision doing this. And, in fact, it’s being done in labs.
WILLIAM BRANGHAM: As you write in the piece, you say that CRISPR could enormously improve the world, but it could also endanger the world.
How could gene editing endanger the world?
MICHAEL SPECTER: Well, I am not an alarmist, but if you can reedit the genes of a mosquito so that it can’t carry malaria, you can also reedit the genes of a mosquito so that it carries something really bad and…
WILLIAM BRANGHAM: Use it as a weapon?
MICHAEL SPECTER: Sure.
You don’t have to be a science fiction writer anymore to believe that it would be possible to engineer a species — and the mosquito, our deadliest foe, is an excellent example — to transmit something bad.
We’re very focused on being able to break the transmission of this terrible thing, malaria, and also Zika and dengue and many other things, but the truth is, that could happen.
And another thing that could happen is mistakes get made. When you’re talking about editing DNA, you’re talking about changing a species. And that’s not a minor thing. That’s a fundamental, powerful choice. And it will require some tremendous forethought.
WILLIAM BRANGHAM: So, how are researchers, policy-makers talking about this, thinking about this? How do they propose that we manage this awesome technology?
MICHAEL SPECTER: Well, I actually think researchers are doing a fairly good job of trying to think this out.
And what that mostly means is, they’re working in the labs, but they’re very aggressively reaching out to communities. I don’t think policy-makers so far have a clue. I mean, they don’t know what’s coming. They’re so far behind in regulation, it’s even difficult to understand how you would even talk about regulating this technology.
But with the malaria, Austin Burt, who I mentioned, runs something called Target Malaria. And he and a large group of people are working on editing enough of these mosquitoes so that they wouldn’t be able to transmit malaria.
And he’s in Africa already, years before he would ever send a mosquito there, talking to people, teaching people on the ground what the choices are, so they themselves can make this choice.
This isn’t a case where a bunch of Western scientists are going to fly in somewhere with 400 million mosquitoes and release them and say, congratulations.
But there is the possibility of getting people to understand this and make their own decisions. And if it worked, getting rid of malaria is a big deal, and it would also actually be cheap, because there’s no vaccines, there’s no drugs, there’s no coming back.
We’re not there yet, but it’s certainly possible.
WILLIAM BRANGHAM: All right, the article is “Rewriting the Code of Life.”
Michael Specter, thank you so much.
MICHAEL SPECTER: My pleasure.