These mosquito larvae in a lab at Imperial College in London have been genetically engineered
to glow red under a laser.
But that red fluorescence is just a marker -- It’s there to tell the researchers that
something profound has happened.
I ran out and I grabbed my supervisor ... I was like Tony but you know you've got
to look at this.
So we started going through and I read them off one by one and I was like red, red, red,
red and we just...
It was a very crazy time.
We just started screaming and getting super excited.
Since only one of their parents had a copy of the red gene, you’d expect around 50%
of the larvae to be red.
But nearly 100% of them were glowing.
The researchers had hacked the rules of inheritance with what’s called a gene drive.
But the red gene isn’t the point - it’s been linked to a genetic tool that renders
female mosquitoes infertile.
And that’s a huge deal because this isn’t just any old mosquito species.
This is anopheles gambiae, one of the mosquitos that carries the parasite
that causes malaria.
So malaria is mostly a sub-saharan African disease.
It affects people in the Indian subcontinent, Southeast Asia, but it’s primarily a disease
of Sub-Saharan Africa.
And the majority of malaria deaths in any given year in the world, hundreds of thousands
of deaths, are kids under 5 in Africa.
Over the past 15 years, there’s been a big investment in bed nets, insecticides, and
better treatment.
And I think the result has been a lot of steady progress on malaria.
That being said, it’s progress against a really, really high death rate.
Most African countries really want to try to eliminate it and WHO is really in support
of this, they’ve set some targets to achieve in 2030.
And where we stand now, we don’t seem to be on course for achieving those.
While researchers continue to work on a vaccine, genetic approaches to malaria look increasingly
promising.
Genetically modified mosquitoes aren’t new - a company called Oxitec has released mosquitoes
in Brazil that are designed to have nonviable offspring.
But those don’t contain a gene drive, which biases inheritance so that the modification
continues to be passed through a population, though they can also be designed to have a
more local reach.
The idea of driving desirable genes into insect populations dates back decades,
but progress toward that goal jumped ahead after the invention of the CRISPR gene editing
tool in 2012.
CRISPR allows scientists make precise changes to DNA in the lab.
A CRISPR gene drive could let them push those changes through a wild population of insects.
It works by inserting the gene editing tool itself into a chosen segment of the mosquito’s
DNA.
From there, CRISPR induces the cell to copy the package onto the matching chromosome.
Like us, mosquitoes have 2 copies of each gene, one from each parent.
And now that the gene drive is on both chromosomes, it will get passed on to all the offspring,
where it will copy onto their other chromosome, and so on.
So depending on what biologists attach to that package, like the red fluorescent gene,
they can make some drastic changes to wild populations.
There are two broad approaches to malaria mosquitoes.
The team at Imperial College is part of an international group called Target Malaria,
funded mostly by the Bill & Melinda Gates foundation.
And they’re aiming to use gene drives to suppress mosquito populations.
Their drives are designed to spread female infertility or to prevent females from being
born, with the effect of shrinking a population of mosquitoes.
Then there’s a team of researchers at the University of California institutions
who have been developing a gene drive that alters, rather than shrinks, the mosquito population.
It spreads genes that make mosquitoes resistant to the malaria parasite, so they don’t transmit
it between humans.
The World Health Organization has outlined the steps that G.M. mosquitoes should go through
before being deployed. Gene drive research is in phase 1 now,
but to find out if it could really work, they need to test it outside of a lab.
And the researchers say their mosquitoes should be ready for phase 2 soon.
I'm hoping the science is well within five years.
Maybe even half that.
Maybe in one or two years.
A couple of years.
But then that's in the lab in London.
After something’s ready in the lab in London you'd really want to go through very rigorous
testing.
So with every health intervention or technology there’s kind of a spectrum of how much testing
and how much certainty people require before they just try it.
This is always a trade-off in any medical trial, if you develop a drug and it’s a
miracle and it helps everyone, when do you stop the trial and just start giving that to everyone?
Once we have a gene drive that we can release in the wild that could wipe out malaria, every
year we don’t do that is 500,000 to 700,000, mostly kids, dying.
Kevin Esvelt the MIT scientist who’s working on gene drives,
was talking to me and he said Malaria is a case where there are really strong
ethical argument of doing something now today because so many children have died just in
the time that we've been speaking.
I would say at least 20.
And his takeaway from that wasn’t let’s do this as fast as possible.
It’s let’s do this right, because if we don’t do this right, then there’s going
to be a massive backlash and we’re never going to be able to do anything like this
ever again.
Yeah if you move forwards with a unilateral “we are going to save the kids whether you
like it or not,” really does imperil the broader malaria eradication effort.
Target Malaria has begun a lengthy process of building facilities and staff in 4 African
countries, where they’ll be working with non-gene-drive mosquitoes before importing the
gene drive mosquitoes.
And even then, there’s more lab work to do before an actual release.
So the modified one is modified using a laboratory strain.
So you have to do experiments to make sure you incorporate the natural genetic background
of the mosquitoes in the area where you want to work.
At each stage, they’re consulting with local communities and with governments about this
genetic technology that’s designed to spread across borders.
There are no regulators that have handled this before.
Not only just in Africa, but anywhere.
I think i’m curious about you know this notion that we have a public conversation,
we need to get people on board, this notion that that would somehow lead to some clear
consensus or some clear green light.
At some point someone has to decide.
And I’m curious if you have a sense of who that is.
Yeah, that’s the million dollar question and no one I talked to even pretended to have
the answer.
The end game that got alluded to by a lot of people was some kind of agreement by the
African Union about releasing a self-propagating drive.
One tricky thing is malaria does not solely
infect people in democratic countries like Ghana or Senegal.
It also affects people in the Democratic Republic of the Congo,
which despite the name is a dictatorship. Countries with
really unstable and in many cases really awful governance.
So one tricky question is, if the African Union comes together and says yeah we’re ok with
this, is that legitimate?
Are they speaking for people in Africa?
And I think a lot the work that scientists are doing is trying to reach out before that
and trying to start a conversation before that to make sure it’s legitimate.
As the public debate begins, there’s a risk that the politics of genetically modified
crops could spill over to the mosquito issue.
Anti-GMO groups like Friends of the Earth have already called for a moratorium on gene
drive research. They fear it will be misused by agribusiness and militaries and cause unintended
damage to ecosystems.
No one in this is as big of a son of a bitch as nature.
Like, nature is so awful in every conceivable way.
It is completely indifferent to suffering.
But I think many of the things we look back on as humans as our greatest achievements:
getting rid of small pox, penicillin, insulin for diabetics, mass vaccinations.
Those are all things that involved messing with nature and either repurposing or tweaking
things that nature created, for our own uses.
Some of the worst things we’ve made have also done that.
But I look at the earth as something we've got to keep going for us and other
animals but I don’t look at it as this morally benevolent place.
It’s a horror show that we’re trying to manage as best we can and this is an ambitious
but really interesting way to manage it.
For a bunch more information about this fascinating topic,
go read Dylan's feature article on Vox.com.
I'll put a link in
the comments. And if you're interested in genetic engineering more broadly,
we have an episode on our Netflix show
called "Designer DNA," and it's about genetic engineering in human beings.
That's on Netflix, go check it out. Check out all the other episodes too,
we're publishing them weekly on Wednesdays.