# Making a lethal, hard to cure virus?

Basically, my current thought process is to have a virus that causes one to all vital organs to fail upon reacting to its components. It has to make contact with as many people as possible, therefore has to be airborne.

The virus itself would be slow-acting, and can, for example, take longer to cure than it takes to kill, or be extremely hard to detect with countless variants.
What I have so far is:

• A pathogen resembling a normal human cell in both behavior and characteristics, making it hard to detect.
• Bolstering its heat and cold resistance enough that killing it by heating or freezing it would result in killing the host as well. (Giving it general resistances to most common decontamination methods, basically.)
• Making its hosts vitality vary by individuals, although surviving without taking countermeasures is impossible.

I believe some pseudo-science can lead to such results, although my problem lies in its spreading. If it's hard to detect in a human body, then it would be relatively easy to find while travelling by air or water, wouldn't it? And spreading it by body contact is somewhat inefficient, since it would take a long time for it to spread everywhere, and I want its transmission to be as fast as possible.

What I want to know is:

• Are there elements that can attach themselves to oxygen molecules and remain undetectable? If not, then what would a "scientific" approach to making one be?

• What kind of lethal elements to the human body are there that could result in organ failure upon contact, and / or cause visible effects?

• Are there any air filtering methods that can cleanse oxygen molecules enough that such a pathogen would be removed?

• "resembling a normal human cell" will not be a virus. Also, "attach themselves to oxygen molecules" is pseudo-science. Look at the scales. How small is 02 and how big is a cell. – Mołot May 3 '17 at 10:48
• Consider how airborn virues are transmitted. They may be spread in aerosols, dust or liquids. Virus doesn't attach to any molecula, it 'attaches' to the water and/or dust. When neighbour is breathing it consumes this aerosol with the air – ADS May 3 '17 at 11:08
• I would recommend playing a few rounds of Plague Inc. for inspiration - you will likely get more (pretty accurate) ideas from 1 hour of gameplay than 5 hours of reading :-) – trolle3000 May 3 '17 at 13:14
• You should really try the simple game "Plague Inc". Not 100% realistic, but after a few rounds, you'll have a somewhat realistic sense of how infect rate and mortality rate intertwine. – Martijn May 3 '17 at 14:45
• there is already HIV and CFS which is probably a version of HIV. What else do you want to create, these are not enough? – user37804 May 3 '17 at 16:00

First of all, a virus can never behave the same way a human cell does. A virus isn't a cell, it more closely resembles a capsule of proteins which contain some DNA or RNA with the building code if you will. It replicates by hijacking a cell's metabolism and protein producing organelles.

One way to accomplish the slow acting but lethal effect you desire could be the virus inciting auto-immune responses. Basically trick the immune system into believing the body's own cells are pathogens and thus destroying them. You could add in the element that the virus can produce different immune responses in different individuals making the thing lethal and very hard to predict and detect since each individual has a lethal but different reaction. Lastly you could state the virus induces a cytokine storm, an often lethal overreaction of the immune system where it goes completely haywire. Edit: The fact that this virus messes with the immune system can also be the lead cause as to why curing it or developing an effective vaccine is nigh impossible.

As for sticking to air molecules. The molecules that make up viruses are much heavier and larger than oxygen molecules, plus neither oxygen nor nitrogen are likely to form a reversible bond if the virus somehow reacts with said molecules. Then there is the point that the molecule will inevitably be much larger than normal air molecules thus unlikely to foil any scrubber designed to get such pathogens out of the air.

Which brings us to your last question. Equipment to scrub viruses and other pathogens from the air exist, but are expensive and cost quite a bit of energy. Especially if they should be used at large scale as would be needed during an outbreak of this nasty pathogen.

• As for the sticking to air molecules part, would it be scientifically possible for the virus itself to be significantly smaller so that it wouldn't affect its weight? And although oxygen is likely to form a reversible bound, it's still possible to avoid this outcome, although rarely, correct? If neither case is possible, then it traveling by air, remaining undetected, and entering the human body would be highly unlikely, wouldn't it? My aim is to have it enter the human body infallibly, regardless of climatic or geographic differences. – Lucifer May 3 '17 at 10:54
• The virus could have a tough outer protein shell and free float through the air similar to grass pollen. Everyone breathes those in and from the respiratory system the virus can freely invade the body. That way the entire situation of molecular bonding is resolved. – Hyfnae May 3 '17 at 10:59
• I see. Although, wouldn't detection be a problem in that case? I want it to keep a low profile for as long as possible, so if it's floating through the air, a simple check would cause it to be detected immediately, and countermeasures to be developed (regardless of speed, since the virus itself is slow-acting). – Lucifer May 3 '17 at 11:03
• With a pandemic like this scientists are likely to react by exploring every possibility, so even if it bonds somehow they will sooner or later find that out and develop equipment/indicators to detect the virus and the concentration. Usually a virus is detected and identified by its protein markers on the outer shell, make those strange enough and detection will be very strenuous, equally strenuous to the virus bonding to anything. Since scientific accuracy has some playroom in your setting (by my impression) this explanation could function. – Hyfnae May 3 '17 at 11:09
• @Seth If you suppress the immune system you fight a symptom but then the virus can multiply unchecked and basically flood the body. At some point you become more virus than body and die anyways. – Hyfnae May 3 '17 at 13:12

We don't really use antivirals except under special circumstances (HIV). Treatment for viral infection is primarily about treating symptoms and waiting for the body to deal with it. We try to vaccinate (seasonal flu), but on the whole they're not cured.

There are a selection of incurable viruses that once you have, you have for life. Most of these come under herpes group. These are contact transmitted but not often fatal with modern medicine, though they can be dangerous for vulnerable groups.

If you want a virus to be fatal then immune overreaction is one of the most effective options. You could also opt for immune suppression if you want it to remain undetected. This results in a variety of causes of death meaning the real cause, the suppressed immune system, takes longer to be detected.

Airborne transmission for viruses tends to be water molecule bound as they're too heavy for air alone, coughs and sneezes spread diseases. This means that air filtering and cleaning is viable.

• I would react similarily as i did Hyfnae's answer, and ask: would it be possible that the virus itself would be significantly lighter than air, yet still keep its lethal properties? – Lucifer May 3 '17 at 10:59
• @Lucifer, no. Consider that basically only hydrogen and helium are lighter than air. It's possible for larger complex structures to be wind borne, like pollens or fungal spores, but there you're looking at an entirely different approach to the problem. – Separatrix May 3 '17 at 11:09
• @Lucifer: If the virus were "lighter" (i.e., less dense) than air, they'd be carried up towards the upper atmosphere (much like a helium balloon) where they couldn't infect anybody. – Wtrmute May 3 '17 at 15:08

You might want to consider the virus' lesser-known, but quite lethal cousin, the prion

Prions are infectious agents composed entirely of a protein material that can fold in multiple, structurally distinct ways, at least one of which is transmissible to other prion proteins, leading to disease in a manner that is epidemiologically comparable to the spread of viral infection. Prions composed of the prion protein (PrP) are believed to be the cause of transmissible spongiform encephalopathies (TSEs) among other diseases.

The basic gist of a prion is that it causes a "bad fold" of a protein. That protein, in turn, causes more bad folding and so on. The most famous prion we know is mad cow disease, which is so serious that cows infected are mandated to be destroyed. Humans that eat infected meat will eventually die. There is no cure, because prions set off a biological process that cannot be stopped.

Prions meet all your disease requirements, save the transmission. Typically you get sick by direct exposure to infected tissue, but all you need is an agent that triggers production of a prion. Make your prion-inducer airborne and, by the time people realize they're sick, it's too late to stop.

• I've actually read up a bit on Prions before asking this particular question. Considering the specifics of making one and the transmission requirements, i found it to be a little too complicated to use when a virus could be more effective. For the moment, I've discarded the usage of lesser pathogens, easily intercepted ones, or ones that are "too complicated to use" for my current setting. That and, prions would be slightly faster acting than a virus. I'll reconsider the usage since an airborne agent doesn't sound that bad, though i'll likely stick to my current scenario. – Lucifer May 3 '17 at 13:42

Prions.

Prions are not viruses but a infectious and pathogenic version of a specific normal cellular protein. "Reproduction" occurs because on contacting the normal version, the prion protein catalyzes a switch of the normal protein to the pathogenic prion isoform.

Prions are most famously known as the etiologic agent of mad cow disease. Diseases in humans caused by this protein include kuru and Creutzfeld-Jakob disaease. The prion isoform of this protein becomes resistant to normal cellular housekeeping and clearance, and so accumulates. As it accumulates it progressively impairs neurologic functions. All the prion diseases are inexorable, untreatable, fatal neurodegenerative diseases.

Prions are extremely resistant to destruction and normal methods of sterilization adequate to kill viruses and organisms can fail, including heat, cold, formaldehyde, radiation (UV or ionizing) and bleach solutions. Prolonged heat, strong acids or strong bleach is necessary. Prions from dead or sick animals can remain in the soil for years or even decades, and infect animals set to graze on tainted pastures.

Readers on this site will be familiar with zombie lore and to me the prions seem zombielike: indestructible deranged versions of a normal entity, able to convert the normal version to the deranged version with a touch. Zombies generally do not persist in the ground for decades. Although...

Re airborne: this absolutely can happen. Usually transmission is by eating infected material but there have been cases of transmission by cornea transplant and other solid organ transplant. Aerosol transmission has been demonstrated in deer. Basically if a copy of prion protein can get into you and contact a normal version of the protein, the disease has begun. The question is how fast it will progress and whether you die of something else before your brain gets sick. I think the reason mad cow did not wipe out the UK is because the cow version is dissimilar enough from the human version that it is a less effective catalyst. There is a known species barrier to transmission such that infection is easier between some species than others.

Re filtering it out of the air: maybe. You can filter out any particle. I looked it up and found a volume for a single prion protein: 30 nm^3. I was surprised it was so big; this is the same size as polio virus and on the order of many others. Viruses are presumably made of many proteins so I don't understand how they can be the same size. In any case, you would need a good filter to get rid of particles this small. It would be slow going.

• I see. Then the problem woud then lie in the specifics of how to deal with it. Since a prion is uncurable, a quarantine to afflicted individuals would solve the problem as soon as it's identified, which shouldn't be that hard. And since a prion lying dormant isn't a very probable scenario, we can say that it being detected before infecting every human alive is highly likely, since death rates would jump up significantly near its original source. – Lucifer May 3 '17 at 14:05
• Prions take a long time (months to years) for enough to accumulate to make a person sick but they are infectious long before that. This is how at least some of the transplant associated cases occurred: the donors were not known to have a prion disease. Prions lay dormant in the environment for many years. Re detected before infecting every human: it took a long time for HIV to be detected despite causing elevated death rates near its source for many years. – Willk May 3 '17 at 15:04

I suggest a highly contagious viral infection that damages the DNA and causes multiple forms of cancer.

There is ample evidence of the virus-cancer link. In fact, the CDC states that

Virtually all cases of cervical cancer are caused by HPV (Human papillomaviruses)

The virus can have very mild symptoms and go away. Only a few months later, the previously infected person goes to the doctor and finds out that they have cancer tumors throughout his body. Finding the link between a very mild "summer cold" virus and this deadly form of cancer would be very difficult. The doctors would not be thinking infectious cancer and would assume an environmental cause. Only later, when the numbers of suffers dramatically increased would they realize it was spreading as an infectious disease. It would take quite a while to isolate the virus, and then years to formulate a vaccine (assuming that it doesn't mutate like the flu virus.)

• In this same vein would be the HeLa line of immortal cells – Machavity May 3 '17 at 18:25
• Unfortunately, this is a bit different than what i'm looking for. Since cancerous tumors are lethal, though take a long time to kill the host even after symptoms appear, even if vaccination would take a long time, it would still be possible before the virus spreads everywhere / kill the hosts. And regardless of the effectiveness of the vaccine itself, it would still weaken the virus upon being applied. – Lucifer May 4 '17 at 9:29
• Vaccines work by identifying a pathogen as a foreign agent and thus triggering an immune response. If the virus damages the DNA and then goes away, there would be no virus present for a vaccine to help, and the damage would already be done. If the cancer is widespread, death could occur in weeks. – Andrew Neely May 4 '17 at 15:01

A possible way to have the virus spread quickly yet be deadly is to have a double effect. Shortly after infection, it basically acts like the common cold. The common cold spreads quite effectively every winter, but is neither feared much nor do people take too strict measures to avoid it. So if in the short time frame, your virus is effectively indistinguishable from the common cold, it should have no trouble spreading.

As the next step, it would take a strategy from the herpes virus: The herpes virus can hide for an extended time in nerves, invisible to the immune system, and not showing any symptoms, until it "wakes up" and gives symptoms again. Your virus could do the same after the initial common-cold effects. This dormant phase would make it harder to connect the activity after "waking up" to the previous infection, especially given the distinct symptoms (see below). I think about three months should be enough to obscure the connection.

In the third step, after waking up it would no longer be harmless. Since it is already hiding in nerves, those would also be the obvious point of attack. Basically it could cause the nerves to stop working. A failure of the nervous system would certainly be deadly. If it doesn't come with other symptoms (especially without release of new virus particles), it would probably be hard to find a connection to the seemingly harmless virus.

Of course after some time, someone will notice that those dying from that mysterious nerve failure syndrome all had an apparent common cold three months earlier. But at that time, many will already have been infected, and with the viruses hiding in the nerves, treatment will be hard, if not impossible. But of course there will be an attempt to at least prevent new infections. But here the virus could implement a strategy known from influenza and HIV: It could mutate its structure frequently. That makes it hard to develop vaccines against it, as any vaccine will only protect against the mutations it was developed from.

As additional infection vector, it might also infect animals, however without those animals showing the deadly symptoms, so it goes unnoticed in farm animals which then get slaughtered normally. If the virus then survives cooking, eating meat could be an additional vector for infection. That would also make it harder to find the connection, because the meat-infected humans would get the nervous system breakdown without a previous apparent common cold,as the virus in the animals would already be beyond that phase when the meat is eaten. Thus would cast doubt on the connection between apparent common cold and nervous system breakdown, and therefore delay understanding, and thus fighting, that illness.

Could a virus stick to an oxygen molecule? Well, sort of, in the same way that an elephant could stick to an ant. It's certainly not going to be undetectable if someone is looking.

An oxygen molecule has a chemical formula of O2. Uracil, which is one of the components of RNA, has a chemical formula of C4H4N2O2. And one uracil is nowhere near a whole RNA molecule, let alone a whole virus.

But, it could be hard to correctly detect without being tiny enough to attach to single molecules. You found what appears to be a human skin cell in the air where this sick person is? That's about as noteworthy as finding carbon dioxide in his breath or white cells in his blood. People shed skin cells into the air all the time.

• I suppose that could work in pseudo-science, which was my backup approach, although several other answers hinted towards the unlikeliness of its attachment, since we'll have a weight constraint to deal with. – Lucifer May 4 '17 at 7:55

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