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I've understood that a virus is not a living organism (like e.g. a bacterium). From Wikipedia I get that a poison is a substance that reacts physically or chemically with molecules in the human body. Since a virus is a protein that binds to certain cells in the body and alters the cell's function in a harmful way (resulting in the production of more viral matter), why is a virus not a type of poison? (Or is it?)

Additional info: I'd like to understand the difference between them—if any—on a chemical and physical level, as well as the consequences for treatment. For example: we all know by now that viruses can only remain harmful/intact on surfaces for a certain amount of time. However, I would think that a poison on a surface does not have such a time limit (but I may very well be wrong). What's the difference, if there is one? Why is licking a banister with viral load older than 4 (or so) days not harmful, but is licking a banister with poison older than 4 days?

Laura
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    Does poison have genetic material or can it divide like virus? Is it considered living when inside a cell, like viruses? – Ojasvi Sep 01 '20 at 05:03
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    I am voting to close this question as it is about the use of the English language, not about biology. – David Sep 01 '20 at 06:46
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    @David I'm very confused by your attempts to shut down questions about viruses. Before posting I had also checked this relevant question and you did the same there. I initially wanted to post this to MED or Chemistry but according to WP, both poisons and viruses are in the realm of biology. Your suggestion of sending this off to a linguist is strange and absurd. – Laura Sep 01 '20 at 10:06
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    I see this as a valid question about terminology in the field of toxicology, which can be rather specific and sometimes inconsistent withing the field, and with common usage of similar terms in the English language. – MikeyC Sep 01 '20 at 14:06
  • Welcome to Biology.SE! Your question is about definitions — i.e. word usage. That seems sufficient to explain the comment by @David. As a new user please also take the [tour] and then go through the help pages starting with [Ask] questions effectively on this site. From that you will see that questions should be focused, that separate questions should be asked separately (not mixed together), and that we expect evidence of prior research, especially for something that meets the criteria for "homework". Thanks! – tyersome Sep 01 '20 at 17:36
  • @MikeyC — The poster's doesn't mention that she is a student of toxicology, but I suppose that it is the question rather than the poster's intent (she doesn't make that clear) that is important. But if you regard this as question in toxicology, do you think it is of any importance to biology or the concerns of SE Biology? Is it related to some "actual problem she/you have faced"? And does some definition used by professional toxicologists (one no doubt you could link to) have any relevance to the average biologist, let alone person? Really? – David Sep 01 '20 at 22:29
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    Thank you all for the info. I still don’t really understand how we got to semantics but that may be my inexperience with both fields. I asked the question assuming scientific words have fixed objective meanings so different words denote different physical systems/objects/interactions. (Rather than denoting connotations etc.) I’m very surprised that does not seem to be the case for poison/virus but I guess this is part of an answer to the question then :) I don’t understand though why two fields of study exist (virology and toxicology) if the difference between them is purely semantic. – Laura Sep 02 '20 at 04:46
  • @David — Are you asking if the language used by biologists is of any importance to biology? "Really?" The fact that you suggest a formal definition used by specialists has no relevance to the average biologist/lay person underscores the importance of this kind question. Scientific jargon can obfuscate the intended message from non-specialists, especially when it overlaps with but differs in meaning from common parlance. – MikeyC Sep 02 '20 at 15:08
  • @Laura — I can see how it might seem like a purely semantic distinction, but it becomes meaningful in an interdisciplinary field like toxicology, which often overlaps with other biological fields like immunology and infectious disease. If we didn't have a convenient way to distinguish infectious biological agents (like viruses) from the poisons they sometimes produce, it would quickly get confusing trying to describe the mechanisms of disease etiology in a clear and concise way. – MikeyC Sep 02 '20 at 15:24
  • @MikeyC — No. I am asking about the one specific case of a word that long predated modern biological science and does not describe any biological process, and I doubt whether you will even find in a textbook of biology, except perhaps tangentially. This is a common word in the language of which everyone has an interpretation from centuries of usage. I am asking how knowing the particular definition a specialised field like toxicology has adopted will help with a real biological problem she has encountered, (A student preparing for an exam does not hack it. And her bio says she’s a physicist.) – David Sep 02 '20 at 16:30

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Although "Virus" literally means "Poison" in Latin, it would be a great over-simplification to regard a Virus as a Poison.

Now, most poisons are chemical compounds that interfere in some chemical pathway in our body. For example:

  1. Carbon Monoxide: Binds with Haemoglobin, rendering it unable to transport oxygen
  2. Sarin: Indirectly inhibits degradation of the neurotransmitter "Acetylcholine" at the synaptic cleft. Mechanism of action of Sarin

Hence most poisons are quite "simple" in their actions. However, viruses can be considered as a complex machinery of functions that interfere with a multitude of processes in our body including cell transcription, receptor-mediated endocytosis, et.c

Hence, the best analogy would be to consider a virus as a tactical poison.

Now, as for last question, viruses are fragile assembled structures. Viral Self-Assembly Viral Capsid

Environmental factors like heat, uv-light, oxygen, etc may damage the assembled structure. Hence, viruses have a self life, and so do may poisons. Sarin (self life)

However, poisons tend to have a longer self life because chemical compounds are more stable than the capsid of viral proteins with weak hydrogen bonds.

As per David 's suggestion, poison is defined as "...substances that cause death, injury or harm to organs, usually by chemical reactions or other activity on the molecular scales, when an organism is exposed to a sufficient quantity." Wikipedia

Viruses do work at molecular level, but not in the same sense as poisons do. Hence, viruses do fit into the description of poisons but not precisely.

Hope you find this helpful.

AkashdeepKar
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  • What is your definition of "poison" and the basis for believing it is correct or universally applicable? – David Sep 01 '20 at 22:34
  • Thanks a lot for this and the examples. Sorry if this is a misguided question but are there any non-viral or ‘simple’ poisons that are transmissible in the same way a virus is? It seems to me a virus is unique in that one of its tactics is causing replication of itself, making transmission possible because of the sheer quantity of the substance in the body. Is there a toxin that can do the same? – Laura Sep 02 '20 at 05:12
  • The closest example that I can think of are Prions, which are just misfolded proteins molecules. Synthetic prions can be aerosolized and used as a slow poison . They cause a cascade of protein deformation, leading to a slow neurodegenerative breakdown. They are naturally transmitted via cannibalism of eating infected mammalian brain in general.(https://www.defenceiq.com/air-land-and-sea-defence-services/articles/prions-as-bioweapons) – AkashdeepKar Sep 02 '20 at 05:36
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Virus is more complicated than just a protein. Rather it is a collection of proteins and nucleic acids (the viral genome), packaged in a certain way. When virus penetrates a cell, it hijacks the cellular machinery, making the cell produce many copies of the initial virus.

Unlike a cell, virus does not have all the necessary elements for reproduction, i.e. for copying its genome, generating all the necessary proteins, and ingesting food for powering this reproduction activity. This is why one says that viruses are not alive, whereas cells are alive. A cell can exist and reproduce without virus, but not vice versa.

A poison can a simply a small molecule (not necessarily an organic one) which is capable of disrupting normal functioning of a cell, e.g., by binding to some of its proteins.

Roger V.
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Is a virus a poison?

In toxicology, a virus is not classified as a toxic agent or a poison but as a biological agent (regardless of whether you consider it to be living or not). With the main distinction being the biological agents reproduce. You can find different definitions of "poison" in different sub disciplines of toxicology, but generally it's any substance capable of causing toxic effects in relatively small quantities. A "substance" in this case is considered to be a single agent. Just as salt-water is not a single substance but a mixture of substances, a virus is a structured organism made of proteins, nucleic acids, and other macro-molecules. Its often the case that none of these different parts are solely responsible for the toxic effects of a virus, but instead it's the action of viral replication which causes cellular damage leading to disease.

There are some biological agents which also produce toxins or poisons. One example is Clostridium tetani. This organism can infect an open wound, but it's toxicological effects are not a result of direct tissue damage caused by the organism, but of the tetanospasmin toxin it produces, which is a potent neurotoxin and the causative agent of tetanus. Again, in this case, C. tetani is the biological agent, but tetanospasmin is the toxin/poison.

we all know by now that viruses can only remain harmful/intact on surfaces for a certain amount of time. However, I would think that a poison on a surface does not have such a time limit

Neither statement is universally true. There are viruses that can remain infectious for months in the environment, and some bacterial spores that can survive for years. There are also some insecticides (poisons for insects) that breakdown in a matter of days in the environment. It just depends on the specific properties of each different agent, and on the environment they are in.

MikeyC
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  • You mention the scientific discipline of toxicology, but — like the other answers — argue an opinion rather than cite a definition of "poison" and explain its practical relevance. – David Sep 01 '20 at 22:32
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    I provided a definition of poison, and discussed it's relevance to the question. – MikeyC Sep 02 '20 at 14:32