Zombies have been a part of popular culture for decades. The living dead rising up to take over the world is a terrifying concept, worthy of Hollywood blockbusters and television hits. Some of those zombie fiction stories are based on infection by viruses or other organisms.

Is it possible to bring dead tissues back to life by virus infection?


3 Answers 3


You must tell facts from fiction; viruses need living cells to replicate because they do not have the molecular machinery at hand to generate energy and construct building blocks essential to life. So no, viruses cannot bring back the dead or revitalize dead cells.

One thing that comes close to it are the so-called zombie ants. These ants have been infected by a parasitic fungus that can take over the ant's nervous system (Fig. 1).

![zombie ant
Fig. 1. Zombie ant found in Brazil, infested with the fungus Ophyocordiceps. Source: National Geopgrahic.

These fungi eventually kill their hosts, but before doing so they temporarily take over their nervous system. In the case of Ophyocordiceps unilateralis (Evans, 2011), the spores lodge themselves into the ant's head through an exposed part of the ant’s exoskeleton. The fungus then infiltrates and targets the ant’s brain, taking control of the ant. Then it makes the ant leave its colony and head for a leaf that provides the ideal conditions for the fungus to grow. The ant crawls under the leaf and goes into a “death grip”—biting down hard on the leaf's major veins. This allows the fungus to slowly feed on it. When the fungus finishes growing, it eventually kills the ant and releases its spores (Source: Smithsonian).

The interesting thing is that the zombie ant not only provides shade and humidity when hanging under the leaf, it is also positioned directly on top of the ant’s colony, so when the spores burst out they fall on other ants and begin the cycle all over again. There are hundreds of mind-controlling fungi like this one, but the chances of this type of parasitoid fungus evolving to target humans as hosts are unlikely (Source: Smithsonian).

- Evans, Commun Integr Biol (2011); 4(5): 598–602

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    $\begingroup$ Ahh yes... youtube.com/watch?v=XuKjBIBBAL8 $\endgroup$ Jan 28, 2016 at 18:12
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    $\begingroup$ You have to wonder how a fungus could compel an ant to do something like this. Minor behavior changes? Sure. I guess it could just stimulate an area of the brain making the ant go into a rage or make it docile or something. This is a very specific set of "instructions" that it seems to be able to feed into the ant's brain though. Considering I'm sure all ant's nervous systems develop partly as a result of their environment, how could it reliably control a new ant? It's amazing. $\endgroup$ Jan 28, 2016 at 18:20
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    $\begingroup$ Mammals are not immune: phenomena.nationalgeographic.com/2013/04/26/… There is a parasite that causes mice to no longer fear cats - so the cat can ingest it where it can then reproduce. $\endgroup$
    – kwerle
    Jan 28, 2016 at 22:47
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    $\begingroup$ Certain parasites including bacteria and worms have been linked to causing obesity by releasing hormones or disrupting our digestive system to make us want to eat more. While not all obesity are caused by parasites, parasites can cause enough behaviour change to cause obesity. $\endgroup$
    – slebetman
    Jan 29, 2016 at 5:14
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    $\begingroup$ @Carcingenate I asked somebody who researches these ants and fungi that exact question once. From what I remember, she said that ants can't control their body temperature directly to attack an infection, so instead they move to a sunny place to induce a fever. I'm not sure about the clamping reflex. $\endgroup$ Jan 29, 2016 at 13:46

Note: This answer is a complement to @AliceD's answer, and is partly reusing stuff from this related answer.

Since you are specifically asking about viruses, I thought that it might be interesting to mention that similar behaviour changes as those mentioned for fungi can also be caused by viruses. See e.g. this quote from Roy et al. (2006):

In many cases the final interactions, or endgames, between a host and pathogen involve complex behavioral modifications such as the infected insect seeking an elevated position where wind currents can effectively disseminate conidia. Elevation seeking by insects at late stages of infection is a common phenomenon that was recognized by early insect pathologists who noted that diseased lepidopteran larvae, such as Lymantria monacha (the nun moth), infected with baculoviruses migrated to the tops of trees where they died (94). This host-altered behavior was named “Wipfelkrankheit” or “Wipfelsucht” (meaning tree top disease in German) for viral diseases (41) and “summit disease” for fungal diseases (24, 57, 106).

Overall, lots of information about the behavioural modifications of hosts caused by fungi and viruses can be found in Roy et al. (2006).

One example of a such a virus that modifies the behaviour of insects is Lymantria dispar multicapsid nuclear polyhedrosis virus, which infects larvae of the moth Lymantria dispar and causes them to climb to high locations (tops of trees) before they die. In another interesting example a parasitic wasp might use a viral infection to control the behaviour of its host, so that the the host beetle is paralysed and is "guarding" the larvae and pupa after the parasitic larvae has emerged from the beetle (see Dheilly et al, 2015 and a popular account in Science).

enter image description here
(Dinocampus coccinellae "guarding" wasp pupa, from http://www.naturespot.org.uk)


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    $\begingroup$ Even the rabies virus is a good example in case of animals. $\endgroup$
    Jan 29, 2016 at 4:33
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    $\begingroup$ @WYSIWYG Rabies is very likely a major source for various “people turning into monsters” folklore, like zombies or werewolves. (“Zombie,” of course, was originally a very specific term for a particular thing in Haitian folklore which does not match up well to rabies, but the broader popular concept certainly gets many nods from the disease.) $\endgroup$
    – KRyan
    Jan 29, 2016 at 14:46
  • $\begingroup$ @KRyan: Not likely. Rabies is also called "Hydrophobia", furthermore Rabies has quite destructive effect on nervous system. Werewolves are not "rabid", werewolves are people who transform into wolves (or other way around) and there is a LOT about people-turning-into-animals and animals-turning-into-people in every mythology of every nation/ethnics/tribe. $\endgroup$
    – Colombo
    Jan 30, 2016 at 3:18
  • $\begingroup$ @WYSIWYG Agreed, and there are probably also many unstudied exampes of how viruses can affect human and non-human behaviour. $\endgroup$ Jan 30, 2016 at 15:53

Stretching the limits of what is known a bit, there is an interesting example of a phage (virus that infects bacteria) infecting a photosynthetic bacterium in the ocean that deserves mentioning. What is amazing here is that the phage has certain genes that are required for photosynthesis within its genome. Why does it have these? The phage extends the life of its host in order to maximize its replication. It has been shown that while the host metabolism is all but shut down, phage genes for photosynthesis are still being expressed at high levels, giving the phage 'bonus time' to replicate. Ok so the virus in question here is the reason for the death of the host in the first place. Also, the host is not exactly living normally during this 'bonus level' of life, as the phage is only trying to produce more of itself. One can imagine however, that in single celled organisms (for simplicity), a lysogenic phage (one that sits in the genome of its host and waits for the proper conditions to jump out and replicate), could theoretically bring back the organism from death, if it encodes the precise biochemical pathway that was shut down in the first place. Think of a cell that has lost some necessary gene that is essential to its survival in a given environment. This new mutation (perhaps because of UV light) would surely kill this cell. If the cellular components necessary for survival remain intact, and a phage encoding this biochemical pathway (this gene) and the components to express it (yes viruses have many of these genes too), it is conceivable that this cell could return to a metabolically normal state, ie living. This is just a thought experiment.... Ref: http://www.cell.com/trends/microbiology/fulltext/S0966-842X(10)00196-4


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