Gene Drives: Green Signal or Back Seat?

Should we use Gene Drive engineered mosquitoes to fight Malaria? Poll results: 972 votes on Google Plus, 11/2015

What is the deadliest animal on earth? If you’re thinking of the great white shark or a venomous snake, you could be wrong. Counting human deaths, it is the innocently named (Spanish for “little fly”) mosquito. Millions, mostly children in third world countries, are killed or sickened each year by malaria, dengue, yellow fever and encephalitis caused by parasites and viruses that are transmitted by mosquito bites. This happens despite billions of dollars spent, years of research and potential cures ranging from vaccines and drugs to public health management. 

Stop or Go, that is the Question: Imagine if the mosquito could kill the parasite before it has the chance to spread to its human victims. For example, the mosquito could be engineered to make antibodies against Plasmodium, killing the parasite soon after it enters the mosquito after a blood meal. Just like a vaccination, nearly all mosquitoes would need to carry this new trait to be effective. There is a way to do this and it is not a new idea. What used to be theory, however, has just become a reality. A new paper published in the journal PNAS has now changed the question from Can we do this? to Should we do this?

What are Gene Drives?: Normally, the chance that any gene trait is passed from parent to offspring is 50%, since only one of a chromosome pair is inherited from that parent. But some selfish genes can copy themselves so that both chromosomes carry the trait, which now affects 100% offspring. A gene drive consists of DNA sequences that provides the technical ability to do this. With the new CRISPR/Cas9 tool that precisely cuts and inserts any gene of interest, the gene drive has become a reality. 

Can Gene Drives work on Humans? Gene drives work best in fast reproducing species, like mosquitoes, that can be released in large numbers. For this reason, they are not going to be effective in spreading inadvertently through humans, or even commercial crops and animals which are bred by controlled processes like artificial pollination and insemination.  

Gene Drives are Natural: For example, a gene called P element swept through all fruit flies in the wild, but is not found in lab strains that were isolated before it spread. 

Gene Drives can be Reversed: For each gene drive that spreads a trait, a reverse gene drive can undo the genetic changes in the original strain. Such reversal drives should be tested in advance, and could be released to stop the spread of any unintended consequences.

What else can Gene Drives do? Besides targeting mosquitoes, gene drives could be used to eradicate invasive species, or reverse resistance to herbicides and pesticides. 

Take the Poll: A public conversation based on sound scientific information, weighing pros and cons, must be the starting point for developing policy. Engineered mosquitoes that could rapidly spread in the wild and eradicate the malarial parasite have been made. Here is the question: Should we use Gene Drive engineered mosquitoes to fight Malaria? 

FAQ on Gene Drives:

Image: Matt Panuska

Pop Science Read:

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84 Responses to Gene Drives: Green Signal or Back Seat?

  1. Not until there’s a phone app to control them with … 😉

  2. Rajini Rao says:

    Haha, coming right up! 

  3. Rajini Rao says:

    charles h Stephens this was news to me too, so I spent the last day checking it out 🙂

  4. Steve S says:

    Remember, the price of inaction is that people die.

  5. ^_______________~

    Well very interesting post anyhow Rajini Rao !!

  6. Rajini Rao says:

    Something else to consider: what if there was a Gene Drive to reverse cancer? Would you still vote No? Weigh the pros against the cons! 

  7. Very interesting article

  8. Mary T says:

    I read about this a few days ago. I don’t think I have enough information to have a valid opinion, although I would love to see malaria eradicated. I’m glad you wrote about this. What do you think?

  9. Well Rajini Rao reversing a cancer gene I guess also means reversing it on individuals and not on a whole population or …

  10. Jesse H says:

    I vote yes Rajini.

  11. Rajini Rao says:

    Mary T I think the GE mosquitoes should be released if they pass independent testing and scrutiny and there is a reverse drive tested and ready in case of problems. The engineered gene has no benefit or deficit to the mosquito. The pros of saving millions of lives outweigh the cons in this case. 

  12. Rajini Rao says:

    Great question, Magnus Fahlén . I brought up the cancer comparison only to bring the disease closer to home, since malaria has been wiped out in the western world (although other mosquito borne illnesses are potentially dangerous, like West Nile virus, etc.). The point of this technology is that it will effect the entire population. So theoretically, a specific type of cancer could be treated with a cancer suppressor gene that blocks it in the entire population. This would take many generations and decades, possibly centuries to work since (most) humans do not reproduce as quickly as flies 🙂 

  13. I first read the graphic as “moggies” – and wondered when we’d managed to gene-splice our way to flying cats.

  14. Aaah I see Rajini Rao well as you say malaria have been wiped out in many parts of the world without this new technology. I think the same goes for any kind of suppressor genes that we must be sure of the effects as well as be able to “control it” before we start to use it.

    Not necessarily with a phone app though … 😉

  15. Rajini Rao says:

    David Archer what are moggies, do tell?  Sordatos Cáceres haha, you got the reference! 

  16. Tau-Mu Yi says:

    I need to read more about this very important scientific advance (CRISPR-mediated gene drive). The reversibility is important for me. We have to be very careful but the potential benefits are huge.

  17. Rajini Rao says:

    Agree, Tau-Mu Yi . CRISPR technology makes a generally cumbersome approach (using homologous endonuclease genes, or HEGs) a reality. The reverse gene drives are also an old idea and should work just as well as the original gene drive. The recommendation is to make, and test them both at the same time. 

  18. Rajini Rao​ Aussie term for a domestic cat.

  19. Rajini Rao says:

    Peter Lindelauf yikes, fortunately you did not come down with a blood borne pathogen through all those bites! It turns out that this technique can be quite simply used to eradicate particular mosquito species as well. Although that does seem more intrusive and akin to playing god, it’s not much different (rather more selective) than the virtual eradication of mosquito species in the west using DDT. 

  20. Agree Rajini and added to this evil deathly behaviour their upsetting insolence.>:-)

  21. Rajini Rao says:

    You draw a vivid picture with your descriptions, Peter Lindelauf ! As for your neighbor’s thought process, I can’t see how dumping diesel on wetlands would increase their property value. 

  22. Rajini Rao says:

    Yet people would seriously consider, and be allowed to use “old school” eradication that is incredibly toxic to the ecosystem whereas a new method is feared because of a vague, undefined threat! We do fear the unknown to the known, however bad the latter is 😛

  23. Mary T says:

    Peter Lindelauf ~ You remind me of a backpacking trip in the North Cascades in my twenties–the mosquitoes, deer flies, and horseflies were so bad, we pulled up stakes and moved our tents onto a high snowfield.  The horseflies found us, but not the others.

  24. Rajini Rao says:

    Ugh, if there ever was reason to eradicate curb a species….

    Edit: I doubt that any new tool will completely eradicate the Plasmodium or the Anopheles, but it’s worth a try. 

  25. Satyr Icon says:

    “What is the deadliest animal on earth?”

    Umm, Humans?

    Which kinda puts a new slant to the poll.


    I voted release the Kraken(s).

  26. Rajini Rao says:

    Satyr Icon according to Bill Gate’s infographic, humans are the second deadliest animal:

  27. Rajini Rao says:

    “Mosquitoes have killed more people than all the wars in history”. I checked out this claim on Quora, and here is one answer (seems plausible): Almost certainly. In any given year, about 500,000 people die from mosquito borne diseases (primarily malaria). Wars, in total, have killed about 100,000,000 people (most of those in World War I and World War II, which account for roughly two-thirds of that total), so mosquitoes will kill that many people every 200 years without fail and have been killing people since ancient times.

  28. Satyr Icon says:

    Rajini Rao that infographic says “dangerous to humans”.

    In context your above question “What is the deadliest animal on earth?” is about humans, but the question standing on it’s own, the most dangerous animal to all animals, past, present and future, would be humans without a doubt. We’ve probably wiped out several hundred thousand species before we even discovered them.

  29. Rajini Rao says:

    Satyr Icon good point, we are certainly the deadliest to all other species, and close- if not the most, deadly to ourselves as well. 

  30. Satyr Icon says:

    Rajini Rao if I wanted to quibble I’d say bacteria, or virii, or whatever that creature that comes out of mosquito’s are the deadliest. Not the poor vector itself.

    However the proposal you posted about targets the malaria bug, and not the mossie. So credit to the researchers for that.

  31. Rajini Rao says:

    The mozzie could be easily targeted by the same technology as well, Satyr Icon . As I commented earlier, that seems filled with hubris but is actually a more selective version than spraying with DDT. 

  32. Rajini Rao says:

    In the linked paper (advanced read), a scientist showed how the gene drive could skew the sex ratio of mosquitoes to be 95% male, effectively curbing the population. 

  33. And here is another infographic that shows that Bill Gates knows what he’s talking about:

  34. David Lawson says:

    Rajini Rao a gene drive to reverse cancer?, well an unintended effect may be a billion more smokers.

  35. Rajini Rao says:

    David Lawson not really, the analogy was to make the disease closer to home as I explained. Theoretically possible, but not practical. The CRISPR technology can remove cancer causing genes or replace broken tumor suppressor genes.

  36. Sakura black says:

    Why did god ever made mosquitos if the females drink our blood and gives us parasite.😑😑😑

  37. Aren’t these convoluted methods? What about providing them a blood substitute that is tastier to them and that kills them soon after.

  38. Paul Forster says:

    The science is sound and it could save many lives but the fear, founded or otherwise, is that nature trends to find a way to survive and adapt. What could it become? Here in Australia we messed up with the introductions of cane toads and the unintended consequences have been detrimental to local wildlife.

    That said I’ve worked in Ghana and watching people with malaria is heartbreaking. Thankfully we had a doctor who was a virologist specialising in malaria in town.

    Perhaps a biodome for a trial run for a few generations of edited an natural might safely prove the teach?

  39. Rohan says:

    Rajini Rao​ the idea is good but as with any science could be misused by targeting specific DNA traits (think Stunex computer virus)

  40. Rajini Rao says:

    Sowmyan Tirumurti I would describe the method as sophisticated, rather than convoluted, as much of technology is these days. Genetic technology is highly advanced, as is electronics for example. Yet, we don’t object to using high tech gadgets in our lives (even if the vast majority of us do not understand how our gadgets work), so why hesitate using advanced technology elsewhere?

    Assuming one can formulate a blood substitute that female mosquitoes prefer to feed upon, it would have to work so well that human bites are completely prevented and we would have to distribute it to every corner of India and every African country. Does this seem feasible? 

  41. Sakura black says:

    Chris Johnston That is true but theres a reason why we kill and eat animals is because its in our nature and I’m not saying humans are good or bad but thats what we did in the Stone age. We hunted and killed for our survival and sometimes we had to kill for protection from other animals. I really do wish that people would stop killing humans and animals for food tho!!😃😡

  42. Rajini Rao says:

    Paul Forster you bring up the arguments for and against this new technology thoughtfully and clearly, thank you. GM mosquito trials have been going on in the field for some years now, and it would be useful to evaluate their effectiveness. There was a trial in the Cayman Islands, one in Brazil and more recently in Florida. e.g., 

  43. Paul Forster says:

    The technology is proven then it would be wrong not to deploy the GD mosquitoes. We have another disease here, Ross River, from mosquitoes that’s common, not deadly, but can be very debilitating . This one is isolated to Australia and Papua New Guinea for the most part.

    Chikungunya is another nasty one that could be eradicated or diminished too.

  44. Bill Collins says:

    We should do it. As you say, we should have the reverse trait ready to go as well in case of a backfire. And here’s the thing. Take out malaria, if not mosquitos, and what will take their place?

  45. Rajini Rao says:

    Many more mosquito borne diseases out there, Bill Collins . Dengue and chikangunya are becoming epidemics in some countries, including India. There are similar GM strategies against them. 

  46. Bill Collins says:

    Yes, I was thinking more along the lines of “what if all those diseases are gone?” Will virii or fungi or something else start to move into the niche? Something harder to eliminate. I still agree with getting rid of them, but it could be like the antibiotic problem.

  47. Rajini Rao says:

    Ah, yes. The best we can hope for is to stay one step ahead of viruses, bacteria, parasites and all manner of pathogens in the fight for survival and evolutionary one up-manship! We have eradicated polio and small pox but many more infectious diseases have taken their place. The antibiotic problem is a case of indiscriminate overuse leading to resistance. We would have to find new drugs or attack the bacterial infections some other way (immunizations, for example). 

  48. There is no money in Malaria drugs because the people afflicted with the disease are poor. The Greenie elites, hate poor people. No power for you, no flush toilet for you, here have a wind mill instead or perhaps a solar panel.  Can I interest you in a carbon credit today?

  49. Rajini Rao says:

    Edward Mclaughlin stop right there with the conspiracy theories. FYI, artemisinin, the state of the art drug used in malaria treatment today, is provided by drug companies, in collaboration with WHO, at a non-profit basis. Look it up. 


  50. Pedro Olivo says:

    Very good information, thank you Rajini!

  51. Most dangerous animal in the world? Humans for sure!

  52. Walt Carr says:

    If only we could genetically alter homosapians to be less warlike creatures. Sure we have genetically manipulated all our food supplies, the Patent held by huge corporations, It’s just a matter of time, evolution will retaliate…then we are in for a big surprise!!!

  53. Walt Carr says:

    Hide your face cowards

  54. Rajini Rao says:

    Walt Carr to whom are you referring? Please explain. 

  55. Walt Carr says:

    All the ISIS cowards who want to kill America’s, this is Isreal’s bloody war. Americans are expected to fight everyone’s wars. It’s time for all wars to bloody end. And men should get vaccinated to reduce the world’s population. let my opinion speak for themselves, US State Department, because they make good money building war machines. Have a pleasant day,

  56. Walt Carr says:

    Any other questions?

  57. Rajini Rao says:

    Walt Carr you are completely off-topic and this post is not the place to state your political views. I will be removing further non-science related comments along these lines. 

  58. Peter Lindelauf birds, fish and Dragonflies all eat “mozzies”. Colloquial nickname is ” Skeeter’s” here in s. US.

  59. Rajini Rao yes, please remove, Thx.

  60. Bisfiren Enilno it is…

  61. Paul Forster says:

    Looks like the Zika virus should be added to this target too!

  62. Hello gd morning.. me i following your page. B couse i like it. Thanks and god bless.

  63. TAIJ KRISHEN says:

    Thanks Rajni Rao This is very Good News

  64. Very interesting reading

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