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View Full Version : Contagious disease, possibly a retrovirus that affects DNA



L M Ashton
01-13-2012, 06:42 AM
I've searched through past threads that talk about retroviruses, and while they've helped clear up some things, they haven't answered my question. Here's what I need:

It's science fiction.

I need a contagious disease that will alter DNA to change how the human body will function. The disease needs to kill a significant percentage of people - 90%+ - and those who survive will have mutations. Some mutations will be good - increased strength, intelligence, other abilities - while some will be bad - decreased strength, intelligence, and so on. Some survivors can remain unchanged if need be.

I've thought of using a massive solar flare (by massive, it could be an asteroid or comet hitting the sun) to mutate existing retroviruses. I've also thought of having a variety of retroviruses being used as gene therapy for a wide variety of genetic defects, therefore increasing the variability of how the mutated retroviruses would affect humans.

Since it's science fiction, I'm not relying on present-day technology. I'd like to know what's plausible and how. I'd also like to know what kind of symptoms this contagion would cause, and would the symptoms vary depending on the retrovirus involved? I'm also guessing that some people could be affected by one or more retroviruses, resulting in them most likely dying faster.

Thoughts?

thothguard51
01-13-2012, 07:47 AM
DNA mutation is generally traced to one of two things, and sometimes both...

1...Mistakes that occur when a cell copies itself for cell division. This can be a natural mutation and can have benefits or be very deadly...

2...DNA damage from environmental factors such exposure to radiation, ultra violet light, chemical pollution and other such things are known factors. We can also add man-made manipulation of DNA to the list.

Not sure your sun flair would work as the primary cause because the earths atmosphere would reduce the risk. If the sun flair was as large as you suggest, I would be more worried about it burning away our atmosphere. By the way, things slam into the sun all the time, or so I have read.

How about a meteor that slams to earth, carrying with it a new disease. I like meteor better than asteroid because the meteor has a better chance of surviving re-entry than an asteroid.

Or since its SF, you could have asteroid miners bring the new disease back to earth with them in the minerals they collect. And since its new to earth, scientist would have to know what they are looking for and once its release and combined with our air or water, it keeps mutating, making it even harder to identify. Or something like that...

I think it really depends on if you are writing soft SF or hardcore technical SF/Medical thriller, the later requiring more science fact.

Good luck, sounds like an interesint story with a 90% death rate...

L M Ashton
01-13-2012, 07:49 AM
It's soft science fiction, so I don't need a lot of heavy duty details. But I prefer to deal with something plausible.

The sun flare is not a requirement, just an idea. The source of the mutations don't matter so much, but I do need the mutations with the abilities/disabilities and massive death count.

thothguard51
01-13-2012, 07:57 AM
A mutated Ebola virus... Maybe from expose to the radiation release into the ocean from the Fujimora Nuclear Power accident?

L M Ashton
01-13-2012, 08:13 AM
Ebola, if it's airborne, would certainly kill enough people. Would it be capable of making changes to the DNA of the people it's infected? I don't know enough about either genetics, mutations, or ebola to know.

thothguard51
01-13-2012, 08:23 AM
Radiation will cause DNA mutation...

As for Ebola, here's the wiki link with a lot of information on the five forms of Ebola. Its a very nasty disease as is without having to worry about it mutating and being even nastier.

http://en.wikipedia.org/wiki/Ebola_virus_disease

Not sure though how this disease will cause DNA mutation of humans. For that you might need something unique, as in you own ideas...

Nexus
01-13-2012, 09:09 AM
I need a contagious disease that will alter DNA to change how the human body will function.

Thoughts?

The most famous retrovirus is HIV. It attaches to a protein on our white blood cells that allows it to enter the cell without being enveloped and destroyed. On a side note, some people are resistant or immune to HIV because of mutations in this surface protein. The protein is vestigial and not used by the white blood cells for any function. If it is mutated, the HIV cannot attach and enter a white blood cell - making someone immune.

I believe it is not the class of viruses (retroviruses) that you are interested in so much as the behavior. You appear to be looking for something that changes DNA. Bacteriophages are a retrovirus of sorts when looking at behavioral aspects.

They insert their genome into RNA and the cell either begins decoding it to make virus proteins, or this RNA sits in the genome and the infection becomes latent (ie. the virus may or may not cause an active infection in the future).

Jumping genes - series of base pairs that excise themselves and reinsert themselves in other areas of the genome - are hypothesized as one of the ancestors of viruses. It is not unlikely that the DNA or RNA of these jumping genes couldn't have the code for some protein coating that would cover replicated strands of genetic material. These precursors could have become the first viruses.

Back to the main topic at hand. Retroviruses are specifically deadly because of their ability to hide in DNA for extremely long periods of time that allow it to permanently infect a host.

Here is why it is biologically impossible for the viruses to create "super-strength" or other super powers by happenstance... A mutation that doesn't kill a cell is 1 in a billion. A mutation that doesn't kill a cell AND benefits the cell in some way is even more rare. The likelihood that all of the muscle cells in a body receiving the same exact mutation is impossible. Not only that but every one of us has the same exact number of muscle cells. The reason we are weaker or stronger are the myosin heads and actin filaments (another story altogether). Therefore muscle cells do not reproduce and a strength-inducing mutation cannot spread through the body.

And finally, somatic cells can change all they want in a human. It won't affect your offspring. If your somatic cells suddenly are mutated and you become a grotesque insectoid monstrosity, your sperm or egg will still have human genes - assuming separate mutations didn't also (one in a million) happen to suffer the same exact mutation.

Ok, so enough of me being a party pooper. Most people don't give a heck about that. Logic and possibility mean diddly-sqwat.

If it sounds good, and isn't blatantly-insultingly-illogical to an every-day reader, then it's a fair plot device.

If you want specific and logical sounding pathways for retroviral infection, then let me know and I may be able to help.

As for symptoms, there could be a limitless list of symptoms for this. If it can affect your genome, then it could affect every function and part of your body. So have a field day with that.

An important note about DNA. DNA uses a base pair system. Many people are aware that it is double stranded and therefore T bonds with A, G with C. What fewer people know is that DNA codes for proteins in a series of 3's. Example DNA sequence... ATTTAGCAAT ... the first three letters "ATT" code for a amino acid. This code is universal for Carbon-based life on Earth. So the sequence ATTAGCAAT can be read as "ATT" "AGC" "AAT" - this sequence codes for amino acids.

Imagine a protien having 50 amino acids like this. Now insert 3 new base pairs. Consider this a mutation. The retrovirus is inserting its genome and 3 base pairs are cutting in line so to speak. You have not changed the protein drastically, as it has the same proteins, but there is an extra amino acid in the chain.

What happens if you insert 2 base pairs? You shift the entire sequence of amino acids. 2 base pairs inserted causes the entire protein and every amino acid it codes for to be different. That is called a frameshift mutation. Any addition that is not a multiple of 3 causes a frameshift mutation which results in major changes that will probably kill the cell.

But the other mutations are less dramatic. It might cause a protein to be made that interferes with a negative feedback loop that tells the cells to stop growing. In turn, a sharks tail might grow a little longer. This longer tail allows it to use the tail as a weapon to stun prey when thrashing it around... viola, you have a Thresher shark. That is essentially how evolution works, and this functional mutations.

Hope this helped or was at least interesting.

Edit: HPV - Wart virus and several STD's are very mutative viruses. Ebola, as mentioned before, is not a perfect choice. Yes it has a high mortality, but ebola affects the blood and the cell walls lining your veins. Has no more affect on your DNA than a cup of Coca Cola (probably not entirely true but it gets the point across).

As for sources of mutation - not sure a sun flare will have much affect considering sun flares happen all the time. Maybe a gamma ray burst? Most drastic mutations simply happen. Mutations that occur from everyday sunlight are will cause less drastic mutations that may be beneficial. Radiation causes mutations that are sudden and drastic, and therefore almost impossible to be beneficial.

L M Ashton
01-13-2012, 01:31 PM
Nexus, thank you for your detailed response. I had to read it a couple of times... :D I appreciate you being forthright and telling me it won't work and why it won't work. :)

Now, just to make sure I understand a specific point: so there's somatic DNA changes - changes in the human body - that won't affect offspring, then there's germ cell DNA changes, or changes to the egg or sperm, which will affect offspring. That... complicates things. So, for example, if I have a genetic defect (which I actually do), to cure me, I'd need somatic gene therapy, but to prevent passing it on to offspring I'd need germ cell therapy. So if I went the retrovirus route, assuming that was theoretically realistic using real science, it would either change the current generation or it would change the sperms and eggs, but it would not change both.

Now, assuming science in, say, 50 or 100 years, it's theoretically possible then? This is a story set in the future and I don't know how far in the future it is yet. It'll be where it needs to be depending on where things go. :)

And if it's theoretically possible then, or even if it isn't, what do I need to make it happen, fictionally speaking?

Drachen Jager
01-13-2012, 09:15 PM
(advice intended in the soft SF sense)

I would say your best bet is an experimental retrovirus, one meant to cure Parkinson's for instance, that instead changed other gene-sequences that mutated or somehow got free from the laboratory which created it and spread out from there.

Simply changing people's DNA in a somewhat random manner would kill most people, many in horrible ways, but it could potentially give some people a boost.

Here is an example of a real-life mutant with super-human strength.

http://www.ctv.ca/CTVNews/Health/20070530/strong_toddler_070530/

Nexus
01-13-2012, 09:51 PM
Nexus, thank you for your detailed response. I had to read it a couple of times... :D I appreciate you being forthright and telling me it won't work and why it won't work. :)

Now, just to make sure I understand a specific point: so there's somatic DNA changes - changes in the human body - that won't affect offspring, then there's germ cell DNA changes, or changes to the egg or sperm, which will affect offspring. That... complicates things. So, for example, if I have a genetic defect (which I actually do), to cure me, I'd need somatic gene therapy, but to prevent passing it on to offspring I'd need germ cell therapy. So if I went the retrovirus route, assuming that was theoretically realistic using real science, it would either change the current generation or it would change the sperms and eggs, but it would not change both.

Now, assuming science in, say, 50 or 100 years, it's theoretically possible then? This is a story set in the future and I don't know how far in the future it is yet. It'll be where it needs to be depending on where things go. :)

And if it's theoretically possible then, or even if it isn't, what do I need to make it happen, fictionally speaking?


Well, it's not impossible to assume that a human-created retrovirus could hold all of the genes necessary to infect a human in their entirety. These genes could be activated by feedback loops that turn certain genes on in certain situations.

Every cell in our body has the full genome. For example, skin cells have the genes that make osteocytes form bones - its just that those genes are turned off.

So you have a lot of room with a super-advanced virus made by humans to do all of these things that you are hoping to incorporate into your story.

The problem is that this has been done before, many times over. So the key is to give it a new, fresh twist.

I will try to think of more original ways to get you where you want to be.

Snick
01-13-2012, 11:13 PM
If you want a disease that will have those effects, then make it up. DNA is sometimes altered by viruses, and it is thought that there are section of viral DNA in human DNA.

There was a neat story about a vatiation of the flu altering DNA so that people became as hairy as gorillas: "Hyperpilosity" by L. Sprague de Camp. I don't recall anything else like that.

Chekurtab
01-14-2012, 12:03 AM
Well, it's not impossible to assume that a human-created retrovirus could hold all of the genes necessary to infect a human in their entirety. These genes could be activated by feedback loops that turn certain genes on in certain situations.

I will try to think of more original ways to get you where you want to be.

You have a very good understanding of genetics and virology. I am curious of your background.
Viruses can serve as vectors for the transfer of genes. It takes many years and many generations to transform even the most basic of organisms. This is why we have evolution. LOL.
All the stories like "Alien" and "I am a legend" are pure fantasies.
You may as well go with solar explosion.

Nexus
01-14-2012, 12:27 AM
You have a very good understanding of genetics and virology. I am curious of your background.
Viruses can serve as vectors for the transfer of genes. It takes many years and many generations to transform even the most basic of organisms. This is why we have evolution. LOL.
All the stories like "Alien" and "I am a legend" are pure fantasies.
You may as well go with solar explosion.

I got a degree in Organismal Biology. I had a particular focus on phisiology of fish and genetics. ;)


I also want to mention that our genomes are filled with immense, vast, unimaginable amounts of DNA that do not apparently code for anyhing. This is often called junk DNA, although it serves one amazing purpose.

Imagine this...

An animal's genome has 10,000 base pairs. All of those base pairs code for something important. Sunlight causes a methyl group in a Thymine nucleic acid to double bond with another Thymine, creating something called a Thymine dimer. The cell replicates and during that replication, it must make a copy of the DNA.

However, the replication machinery cannot make sense of the Thymine Dimer. It simply "guesses" what the right base pair is. So it's done... the DNA is changed for this new cell. And since all 10,000 base pairs in this organism code for something, it is guaranteed that the proteins made from this DNA will be different.

And mutations happen all the time. Every second a cell in our body has its DNA mutated. Normally if the cell is badly damged by this change, the cell itself recognizes this and sends out distress beacons (essentially) that alert white blood cells to come kill it. Or the cell commits suicide.

Sometimes the DNA coding for these distress beacons is mutated, and therefore the cell cannot alert the body to its damage, and cannot commit suicide. It then may become cancer.

When every base pair in the genome is critical to proper function, every single change to the DNA will cause damage. Therefore cells will become cancerous or die in mind-numbingly greater nunbers making life almost impossible as it is today.

Now to the original point - junk DNA. 97% of the human DNA does not seem to "do" anything. So you might think that makes it worthless? But it isn't. This drastically increases the chance that an everyday mutation inserts itself or affects a "worthless" part of junk DNA.

And when that happens, the cell is not harmed and lives on. The junk DNA is an amazing buffer against mutation. That is why realistically mutations do not cause such drastic or consistant changes as our fiction stories would like our reader's to believe.

A "smart" virus, engineered with the ability to "seek out" specific functional parts of the genome to cause these changes is therefore the most likely way for this all to go down. But as I said, it isn't necessarily original and not always the most interesting way for these things to happen in fiction. Sometimes the less-likely or impossible source of special human powers is the more fun and interesting plot device.

RemusShepherd
01-14-2012, 12:28 AM
A high death tool from a random virus I could believe. But it's unlikely that a randomly-created virus could cause beneficial mutations.

I write hard biowarfare SF, and every time I want a disease to do any specific thing I end up making it purposely engineered. Given a future where we have complete knowledge of the human genome and how it works, it's possible to imagine creating a virus to do just about anything. But appearing accidentally from a solar flare? That I don't think would work.

The death toll is easy. We know how to put a protein cloak on viruses to make them almost perfectly lethal. (Google 'IL-4 mousepox' if you want a good scare. Or read my comic. (http://www.genocideman.com/?p=164) :) )

Making viable mutations is harder, especially ones that propogate through the generations. I have one trick you might use, however. Some viruses are teratogenic -- they change the development of fetuses in the womb. You could postulate a teratogenic virus that remained dormant even if the victim survived (and a retrovirus would be a good choice for this characteristic). If the virus then resurged while a woman was pregnant it could mutate her unborn child.

If it's a natural disease then the child's mutation will probably just kill it. No thalidomide babies had superpowers. But you might get believable mutations from an engineered disease in a story.

frimble3
01-14-2012, 07:39 AM
I have one trick you might use, however. Some viruses are teratogenic -- they change the development of fetuses in the womb. You could postulate a teratogenic virus that remained dormant even if the victim survived (and a retrovirus would be a good choice for this characteristic). If the virus then resurged while a woman was pregnant it could mutate her unborn child.
Clever! Sort of a 'Midwich Cuckoo' effect. The people who got the virus are all patting each other on the back for surviving, and then the changed babies start arriving. If the mutations are variable, the changes might not even be noticed at first, certainly it might take a while for the connection between the various changes and the virus to be spotted. It might even be the physical changes of pregnancy, (hormones, etc) that triggered the 'awakening' of the virus. Nicely done, in a horrible way.

frimble3
01-14-2012, 07:41 AM
And mutations happen all the time. Every second a cell in our body has its DNA mutated. Normally if the cell is badly damged by this change, the cell itself recognizes this and sends out distress beacons (essentially) that alert white blood cells to come kill it. Or the cell commits suicide.

Sometimes the DNA coding for these distress beacons is mutated, and therefore the cell cannot alert the body to its damage, and cannot commit suicide. It then may become cancer.

When every base pair in the genome is critical to proper function, every single change to the DNA will cause damage. Therefore cells will become cancerous or die in mind-numbingly greater nunbers making life almost impossible as it is today.

Now to the original point - junk DNA. 97% of the human DNA does not seem to "do" anything. So you might think that makes it worthless? But it isn't. This drastically increases the chance that an everyday mutation inserts itself or affects a "worthless" part of junk DNA.

And when that happens, the cell is not harmed and lives on. The junk DNA is an amazing buffer against mutation. That is why realistically mutations do not cause such drastic or consistant changes as our fiction stories would like our reader's to believe.

This is fascinating and comforting, thank you for the information.

Chekurtab
01-14-2012, 11:13 PM
Making viable mutations is harder, especially ones that propogate through the generations. I have one trick you might use, however. Some viruses are teratogenic -- they change the development of fetuses in the womb. You could postulate a teratogenic virus that remained dormant even if the victim survived (and a retrovirus would be a good choice for this characteristic). If the virus then resurged while a woman was pregnant it could mutate her unborn child.

If it's a natural disease then the child's mutation will probably just kill it. No thalidomide babies had superpowers. But you might get believable mutations from an engineered disease in a story.

Teratogenic virus may not affect the mother but is likely to kill fetus. The surviving babies (if there are any) won't change human race. Ashton is looking for a genetic change in human race, which is impossible by any scientific measure. I would instead go down the path well traveled: invent a disease that affects human behavior without messing up with genetics.

MAP
01-15-2012, 11:27 PM
Teratogenic virus may not affect the mother but is likely to kill fetus. The surviving babies (if there are any) won't change human race. Ashton is looking for a genetic change in human race, which is impossible by any scientific measure. I would instead go down the path well traveled: invent a disease that affects human behavior without messing up with genetics.

Sure, but what is wrong with a little hand-waiving in SF?

Here is what I'd do, and yes there would be some hand-waiving, but there will be a little hand-waiving no matter what route you took.

Unless your story requires it, I wouldn't try to explain how the virus mutated. You don't need solar flares to alter a virus. Viruses mutate just fine on their own especially retroviruses. You can also have a new virus infecting the human race. That is completely feasible.

If you want to change the physiology of humans you really have to go with the germ cells. This means that it will be the children of the survivers who will have the increased strength, intelligence or whatever you want.

I would just chose one. Make everyone have the same ability. It makes more sense that the mutation would act in the same way on all those it enhanced, but really do whatever fits the story you are trying to tell.

So what you need is a lot miscarriages and still births. Most of the babies who are born should either be normal (because not every virus is going to infect the germ cells) or have disabilities and defects. Because most mutations are bad. You only have a very, very, very small percentage enhanced.

I would make them all have the same enhancement. Retroviruses insert their genes into the human DNA. The idea is that most of the time it would insert into the junk DNA and not affect cell function. I'm guessing that there would be certain sequences of DNA that would be spots where the viral DNA is more likely to be inserted. If you make one of those spots result in an enhancement of strength or intelligence or whatever, then it would increase the probability of the viral DNA being inserted at that specific spot to cause the enhancement. Does that make sense?

That is how I would do it, but if this doesn't work in the scope of your story, I wouldn't worry too much about getting all of the science right. Story beats scientific accuracy in my mind, but if you can do both, why that is just pure awesomeness.

Good luck.

veinglory
01-15-2012, 11:36 PM
In order to change the DNA in pretty much every cell it would have to be a brand new thing. I wouldn't even call it a virus. Just make it a new nano-live form and give it new name.

L M Ashton
01-16-2012, 07:08 AM
I really appreciate all the conversation, ideas, comments you've all presented. I'll have to mull things over before I decide what to do, but you've all been very helpful. Thank you.