# Is It Possible To Genetically Modify/Engineer A Pathogen To Do One Specific Thing, Even In Theory? **URL:** \ **Category:** Factual Questions\ **Created:** [May 11, 2020, 5:21pm UTC](https://boards.straightdope.com/t/is-it-possible-to-genetically-modify-engineer-a-pathogen-to-do-one-specific-thing-even-in-theory/853589 "2020-05-11T17:21:21Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![HeyHomie](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/heyhomie/32/207_2.png) [@HeyHomie](https://boards.straightdope.com/u/HeyHomie)\ **Post date:** [May 11, 2020, 5:21pm UTC](https://boards.straightdope.com/t/is-it-possible-to-genetically-modify-engineer-a-pathogen-to-do-one-specific-thing-even-in-theory/853589/1 "2020-05-11T17:21:21Z")
Is it possible, either theoretically or even practically, to modify or engineer a pathogen to do one specific thing? Such as to kill or render infertile a more complex organism? Example: are we years? decades? centuries? away from some lab in St. Louis genetically engineering a bacterium that could only multiply in the blood stream of the Asian carp (an invasive species wreaking havoc on the Mississippi River ecosystem)? That pathogen could be specifically engineered to kill or render the fish infertile, while having absolutely no effect on any other species that lives in and around the species’ habitat. Is this possible even in theory? The practical applications of this are limitless. Zebra mussels, kudzu, murder hornets… just about any invasive species could be destroyed once and for all (apart from where they’re not invasive, of course) with this technology. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [May 11, 2020, 5:34pm UTC](https://boards.straightdope.com/t/is-it-possible-to-genetically-modify-engineer-a-pathogen-to-do-one-specific-thing-even-in-theory/853589/2 "2020-05-11T17:34:27Z")
Sure, you could in theory build something that specific. And it would immediately begin mutating beyond your control, losing that specificity, potentially hopping from secies to species. ---
**Author:** ![DinoR](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dinor/32/2821_2.png) [@DinoR](https://boards.straightdope.com/u/DinoR)\ **Post date:** [May 11, 2020, 6:10pm UTC](https://boards.straightdope.com/t/is-it-possible-to-genetically-modify-engineer-a-pathogen-to-do-one-specific-thing-even-in-theory/853589/3 "2020-05-11T18:10:53Z")
More than in theory but the examples are not of the type you imagine. Using viruses as vectors to deliver new genetic material into the cells of already grown organisms is a thing being researched and tested. It is called [gene therapy](https://ghr.nlm.nih.gov/primer/therapy/genetherapy). That is not really a pathogen that spreads freely and reproduces like you were imagining. The [FDA approved](https://www.prnewswire.com/news-releases/fda-approves-first-therapy-for-patients-with-lung-and-thyroid-cancers-with-a-certain-genetic-mutation-or-fusion-301056045.html) a genetic therapy that treats three kinds of tumors a couple days ago. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [May 11, 2020, 7:27pm UTC](https://boards.straightdope.com/t/is-it-possible-to-genetically-modify-engineer-a-pathogen-to-do-one-specific-thing-even-in-theory/853589/4 "2020-05-11T19:27:49Z")
Some purposes are a lot easier to genetically engineer for than others. The easiest case is to engineer something to produce one specific protein. For instance, you can genetically engineer bacteria to produce human insulin. I’m pretty sure that this is in fact the primary source for the insulin used by diabetics, nowadays. If your goal is to kill a specific species, like Asian carp, probably the easiest way to go about it would be to start with an existing disease that affects that organism, and try to modify it to make it more dangerous. But what makes a disease dangerous depends on a great many factors in a very complicated way, so probably the best you’d be able to do would be to generate many random variations and test them out in the lab, basically like a highly-accelerated version of natural evolution. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [May 11, 2020, 8:51pm UTC](https://boards.straightdope.com/t/is-it-possible-to-genetically-modify-engineer-a-pathogen-to-do-one-specific-thing-even-in-theory/853589/5 "2020-05-11T20:51:20Z")
Chances are that some subset of the target species will be immune, or at least less susceptible, to your artificial disease. So you might knock the population of the invasive species way back, but then in a few years the immune ones will come back, meaner than before. OK, maybe not that last bit, but didn’t this happen with a rabbit disease introduced in Australia? ---
**Author:** ![Kent\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kent_clark/32/105_2.png) [@Kent\_Clark](https://boards.straightdope.com/u/Kent_Clark)\ **Post date:** [May 11, 2020, 9:17pm UTC](https://boards.straightdope.com/t/is-it-possible-to-genetically-modify-engineer-a-pathogen-to-do-one-specific-thing-even-in-theory/853589/6 "2020-05-11T21:17:47Z")
Before I retired I worked a lot with the weed scientists at Monsanto in St. Louis. We’re talking about chemicals, not organisms, but one thing they impressed on me was that _nothing works 100% of the time._ Somewhere out there are mutant members of a species that are pretty much immune to something. And they will reproduce, and then your sure method of killing everything will turn into survival of the fittest. ---
**Author:** ![AHunter3](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ahunter3/32/368_2.png) [@AHunter3](https://boards.straightdope.com/u/AHunter3)\ **Post date:** [May 11, 2020, 9:29pm UTC](https://boards.straightdope.com/t/is-it-possible-to-genetically-modify-engineer-a-pathogen-to-do-one-specific-thing-even-in-theory/853589/7 "2020-05-11T21:29:41Z")
> [@Darren\_Garrison](#): > > Sure, you could in theory build something that specific. And it would immediately begin mutating beyond your control, losing that specificity, potentially hopping from secies to species. Yeah, this. Let’s not forget that COVID-19 was specific to something else (bats, apparently) and hopped to us probably as a consequence of a mutation that enabled the little strings to thrive in the human-body environment. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [May 11, 2020, 10:01pm UTC](https://boards.straightdope.com/t/is-it-possible-to-genetically-modify-engineer-a-pathogen-to-do-one-specific-thing-even-in-theory/853589/8 "2020-05-11T22:01:15Z")
> [@AHunter3](#): > > Yeah, this. Let’s not forget that COVID-19 was specific to something else (bats, apparently) and hopped to us probably as a consequence of a mutation that enabled the little strings to thrive in the human-body environment. Yep. Biological warfare is more suicidally insane than nuclear war. ---
**Author:** ![si\_blakely](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@si\_blakely](https://boards.straightdope.com/u/si_blakely)\ **Post date:** [May 11, 2020, 10:21pm UTC](https://boards.straightdope.com/t/is-it-possible-to-genetically-modify-engineer-a-pathogen-to-do-one-specific-thing-even-in-theory/853589/9 "2020-05-11T22:21:53Z")
> [@dtilque](#): > > Chances are that some subset of the target species will be immune, or at least less susceptible, to your artificial disease. So you might knock the population of the invasive species way back, but then in a few years the immune ones will come back, meaner than before. OK, maybe not that last bit, but didn’t this happen with a rabbit disease introduced in Australia? Both myxomatosis and rabbit hemorrhagic disease (calicivirus) have had this issue: > [@wikipedia](#): > > In 1950, the SLS strain of myxoma virus from the South American tapeti (Sylvilagus brasiliensis) was released in Australia as a biological control agent against feral rabbits. The virus was at first highly lethal, with an estimated case fatality rate of close to 99.8%. Within a few years, however, this strain was replaced by less virulent ones, which permitted longer survival of infected rabbits and enhanced disease transmission. The virus created strong selection pressure for the evolution of rabbits resistant to myxomatosis. As rabbits became more resistant the viral strains responded by becoming less virulent. In 1997, RHD escaped a research station near Australia and killed a large number of rabbits on the Australian mainland. New Zealand farmers in the South Island defied the authorities and illegally imported and spread the disease at exactly the wrong time: > [@](#): > > However, it was released after breeding had commenced for the season, and rabbits under 2 weeks old at the time of the introduction were resistant to the disease. These young rabbits were therefore able to survive and breed rabbit numbers back up. Ten years on, rabbit populations (in the Mackenzie Basin in particular) are beginning to reach near pre-plague proportions once again though they have not yet returned to pre RCD levels. It may be possible to use a different strain of calicivirus that was released in Australia in 2017, but for maximum effectiveness, these things need to be researched, planned, and implemented well to have any hope of being effective. ---
**Author:** ![purplehorseshoe](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/purplehorseshoe/32/2996_2.png) [@purplehorseshoe](https://boards.straightdope.com/u/purplehorseshoe)\ **Post date:** [May 11, 2020, 11:50pm UTC](https://boards.straightdope.com/t/is-it-possible-to-genetically-modify-engineer-a-pathogen-to-do-one-specific-thing-even-in-theory/853589/10 "2020-05-11T23:50:50Z")
Holy crap, the New Zealanders really shot themselves in the foot on that one! O.P. it’s tough to locate a biological “target” that exists in that species (like your carp example) and only that species, and is also vulnerable enough to get close to 100% mortality rate if messed with. ---
**Author:** ![Wesley\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wesley_clark/32/20581_2.png) [@Wesley\_Clark](https://boards.straightdope.com/u/Wesley_Clark)\ **Post date:** [May 12, 2020, 1:34am UTC](https://boards.straightdope.com/t/is-it-possible-to-genetically-modify-engineer-a-pathogen-to-do-one-specific-thing-even-in-theory/853589/11 "2020-05-12T01:34:01Z")
Bacteriophages are viruses that prey on bacteria. Some are so specialized they only target one species of bacteria. So it can happen. Also using rna interference maybe you could block a gene crucial for survival that is species specific.