Is it possible that there might be a virus (of the giant, ancient, frozen-in-glaciers type) that is, for lack of a better explanation, double-layered? As in the first layer affects the host and then later, after the host is weakened, the second, inside virus attacks to kill. Is this scientifically plausible?

To clarify, I'm not asking if something like this currently exists. I'm asking if it's possible. If it's something from eons ago that remains frozen in melting glaciers, it may exist yet unknown.

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    $\begingroup$ have you tried google.pl/search?q=double+layer+virus and if you did, what you disliked about the results? As far as I can see, there is a lot of descriptions, ranging from scientific papers to quite simpler ones. $\endgroup$
    – Mołot
    Commented May 10, 2017 at 13:57
  • $\begingroup$ @Mołot unfortunately a lot of the results use scientific lingo that I am not capable of understanding, and yet others aren't necessarily talking about the same thing I'm asking for, which is a double-layered virus that is capable of affecting humans and "going off" to affect them twice. $\endgroup$ Commented May 10, 2017 at 14:00
  • $\begingroup$ A virus is a complex made out of several molecules. There is absolutely no reason why different parts of it (be it an inner part or whatever) can't be responsible for different effects. $\endgroup$
    – Raditz_35
    Commented May 10, 2017 at 14:07

3 Answers 3


It is possible. It exists. An example is Hepatitis D.

from Wikipedia (what would we do without Wikipedia? Give to Wikipedia!)

Hepatitis D (hepatitis delta) is a disease caused by the hepatitis D virus (HDV), a small spherical enveloped viroid. This is one of five known hepatitis viruses: A, B, C, D, and E. HDV is considered to be a subviral satellite because it can propagate only in the presence of the hepatitis B virus (HBV).1 Transmission of HDV can occur either via simultaneous infection with HBV (coinfection) or superimposed on chronic hepatitis B or hepatitis B carrier state (superinfection).

Both superinfection and coinfection with HDV results in more severe complications compared to infection with HBV alone. These complications include a greater likelihood of experiencing liver failure in acute infections and a rapid progression to liver cirrhosis, with an increased risk of developing liver cancer in chronic infections.[2] In combination with hepatitis B virus, hepatitis D has the highest fatality rate of all the hepatitis infections, at 20%.

To summarize: Hepatitis D is a tiny subvirus. It cannot go it alone but parasitizes the mechanisms of hepatitis B, subverting them to its own ends. When you have hepatitis B it is extra bad for you if you also have D.

enter image description here

In reply to @Molots "two wave" comment / question: yes hep B and hep D are different so maybe not what OP wanted.

There are viruses that stage their attack in waves. Epstein Barr virus infects a person and then can come back years later as the driving agent of a fatal cancer like nasopharyngeal cancer or lymphoma.

Feline leukemia virus maybe closer in that it attacks in stages: first a takeover of the immune system where it replicates and masses in numbers (but the animal can still get around), followed by a takeover of mucosa in gut and elsewhere during which the dying animal sheds massive amounts of virus.

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    $\begingroup$ Is it causing "two waves of infection" the way OP asks for? $\endgroup$
    – Mołot
    Commented May 10, 2017 at 15:09
  • $\begingroup$ Don't get me wrong, I upvoted because this is useful info I totally forgot, but I doubt if this works the way this question asked. It seems that the two v works as one, if stronger, virus when combined. $\endgroup$
    – Mołot
    Commented May 10, 2017 at 15:12

OK, there are viruses with multi layered capsid. Fun fact, these are mostly harmless for humans, but can be harmful for cancer [1], [2].

The idea you want, striking twice, has little to no evolutionary sense. Here you have it "by the numbers":

  1. Virus only attack to reproduce.

  2. Killed human does not help them to reproduce.

  3. Strong humans with a lot of strong, well fed cells are best to reproduce.

  4. Only thing virus "want" weak is immunological system.

There is literally no need for virus to kill someone after virus reproduced. Actually, it is worse because host will no longer spread the virus. Most succesful viruses are ones that let their victims spread viruses for quite long time.

The only kind of viruses that kill humans are the ones that, simply, reproduce too fast and overwhelm our systems. But many of them, like pig flu, also "feed" on animals, on which they have less lethal effects.

Natural evolution seems difficult *, for above reasons. But given that there actually are multi-layer viruses, I see no particular reason against something like this as bio-weapon. With weapon, there is actual reason for it to kill, so outer layer as reproduction and inner layer to kill starts to make sense.

* Will's answer shows I may be wrong here.


Your 'virus' is a nanobot

Since you say that it is ancient and frozen in a glacier, I assume that you are implying that it is some sort of alien virus. If so, why not just make it a nanobot.

With any reasonably advanced technology, it seems plausible a tiny bot containing a tinier bot could be manufactured, and that said bot could be used for nefarious virus-like purposes.


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