Let’s first define life. According to the online Merriam-Webster Dictionary, life is “an organismic state characterized by capacity for metabolism, growth, reaction to stimuli, and reproduction.”
Viruses are not living things. Viruses are complicated assemblies of molecules, including proteins, nucleic acids, lipids, and carbohydrates, but on their own they can do nothing until they enter a living cell. Without cells, viruses would not be able to multiply. Therefore, viruses are not living things.
When a virus encounters a cell, a series of chemical reactions occur that lead to the production of new viruses. These steps are completely passive, that is, they are predefined by the nature of the molecules that comprise the virus particle. Viruses don’t actually ‘do’ anything. Often scientists and non-scientists alike ascribe actions to viruses such as employing, displaying, destroying, evading, exploiting, and so on. These terms are incorrect because viruses are passive, completely at the mercy of their environment.
Update: See a more recent post for my thoughts on this question.
although coral is a rock that is alive!
No. I think a parasite would definitely be living.
Im twelve and I say shad up
Only to the lito know it alls
Umm a tape worm needs a host to stay alive, but we count that as living! I think that viruses are just as alive as you and I.
As for their response to stimuli, they can change overtime to have a greater infection rate.
 I think people are just angry at viruses because they make us sick.
Thank you!!! viruses that are dormant are just like when you or I sleep. Are we Dead then ??? NO!
You know how to spell to……
omggg this is so amazing! wooot woot go Beland, yeahhh man.
Go Mr. Beland!!!!Â
But humans without females they would not be able to multiply
If viruses aren’t alive because they require other living things to replicate their DNA then nothing is alive. DNA synthesis requires energy and material from other living things. Animals are, as much as viruses, obligate parasites on the things that make our food. They originated by the same evolutionary process as all other life and use the same material (nucleic acid) for their genes. Viruses can regulate gene expression to respond to their environment; they can “do” stuff, as long as they have the machinary of a cell to do it in, just as we can only do stuff if we have food. They maty not be able to move from one environment to another but for the most part neither can bacteria or plants, are they not alive either?
Animals could in a sense be said to be obligate parasites (like viruses and many bacteria) because we rely on other living things giving us food and raw materials to ‘do’ anything just as the virus relies on our cell. Our microbiota is something we need to live as much as the microbes need us to live – or the virus needs its host. On another level, each gene relies on each other genes to propogate and function. Obligate parasatism doesn’t negate something being alive.
Viruses can change their lifecycle in response to environmental conditions – the lysis / lysogeny decision in phage lambda for example. In large part, bacteria and plants respond to stimuli by changing gene expression, just like viruses, so unless those aren’t alive the logic here seems super inconsistant.
It’s just wordplay, what’s important isn’t weather some label like ‘alive’ is applied but what properties it has (heredity, etc) but the logic for saying it isn’t alive needs comment.
It’s all “virus bad, life good, virus not alive”. It’s poor logic even if viruses are ‘bad’ but that’s an oversimplified view of things. Oncolytic viruses and bacteriophages have important roles in medicine, not to mention viruses as vectors for gene therapy, and most viruses don’t infect us, or their important roles in evolution.
 According to Schrodinger =/= according to thermodynamics. The theory has nothing to say on the definition of life.
Given how many details of molecular biology were discovered in viruses (http://www.sciencedirect.com/science/article/pii/S0960982207010731) if they don’t exist neither do the things discovered in them. Many viral genomes have been sequenced and some have had all their genes charactarised.
You’re not an HIV denialist are you? Viral infections adhere to koch’s postulates as solidly as bacterial infections. Direct methods have never been used to show DNA’s double helical structure – does the lack of photos mean it doesn’t have a double helix?
 Humans have no means of generating ATP – without other “host” organisms. We can make it from sugar but we don’t make the sugar do we now, anymore than the virus makes its replicative machinary.
God why didn’t you point out you’re an anti-scientific conspiracy theorist from the start, then I wouldn’t have tried talking sense to you.
 The Dictionary, always the best place to get definitions of scientif terms, eh? 7th grade biology books aren’t the be all end all of science
In exactly the same ways as viruses, by mechanisms first elucidated in viruses.
Viruses may be active, just as atoms and molecules are active, but they are not “alive,” based on the biological definition of life.  When a virus “reproduces,” it is just a chemical reaction between the virus and the host cell that is producing new copies of the virus.  The host cell has basically become a virus factory.  But this is just production, not reproduction.  Equating viruses to humans eating food is completely erroneous.  It is more like a program that re-writes the computer’s operating system.  That is why they are called computer viruses, not computer bacteria.
you answered my homework too thank you! 🙂
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very useful
just because it needs another cell to reproduce does not mean its not living people need other people to reproduce why is this different
Looks like the people who think that viruses are alive need to first change the definition of “live” that is given, before they talk about viruses in particular.
Sooo… To the people who agree to viruses being non-living: Would you say that viruses are parts of certain cells? Since every virus was crated by a living cell to communicate with another living cells, is a virus an “intruder” that “hijacks” cells, or are cells actively recieving and spreading RNA to each other. (as an intentional design with purpose)
viruses are not alive because they cannot function independently everyone knows that right
Nice info really help on my project
too*….so do you
Tony is a Virus
Reply to Paul Cook
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To sequence a viral genome you first have to isolate/purify the particular virus in question before you can do anything else – this has never been done in relation to the so-called ‘pathogenic viruses’ (any of ’em’) despite the numerous speculative claims and hoo ha to the contrary. In fact I am still waiting for the who, when. where, and how with all the scientific detals and specifics and of course which excludes any reference to the use of polymerase chain reaction method (PCR).
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Thanks for my homework question
Homework check
this really helped my virus debate
Then why did you read this?
virus are dormant like seeds will not grow unless they are planted in the right environment
Actions to viruses are completely passive! Amazing. Thank you for this article.
Dr. Racaniello, do you prescribe to the belief of the renegade host DNA hypothesis for the primary origin of viruses, maybe parasites going too far, our do you think it was a random chance evolution of all the correct proportioned conditions at just the right time to produce this perpetual reaction. Excuse my question if it is covered in your book, I’m trying to figure out how to get it in my hands now.
Tony, I would say it’s because they are very specialized. It hard to imagine such ingenuity happening without any intelligence. I’m really hoping to find intelligence in microbes:) Â
Agreed, we’re all just energy decomposers  in this rat race.
Wow, great imagery!
What about Kelly’s example of viruses being like green plant seeds you grow in the soil. The plant seeds collect their nutrients to synthesize DNA from the soil just like a virus collects their nutrients from their host’s supply.
No, you’re right… Vincent is right… The only way we could consider viruses alive is if we considered the host as an extension of the virus. Even the most facultative parasites who collect their purines and pyrimidines for DNA replication from their host. Viruses are very special… Â
how can a body stop the hepatitis c virus from replicating itself in the liver cells?
 No. Viruses do not reproduce. They replicate within a host cell. In order to be alive, they must be able to reproduce on their own. (meaning asexually or sexually)
Viruses are on the verge of life, don’t consider them fully non-living.Â
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I think it’s silly that people can simply write off the facts given and assume without any other given recource that viruses could be alive. I personally didn’t know this fact, but seeing as the author obviously has much more experience than me, I’m going to believe this. I do wonder though: what classifies dependent parasites? The ones that need either certain host plant life or anything like that?
Listen, I am dying from illnesses resulting from an HIV infection that I obtained directly after having sexual intercourse with a black chick named Black Jackie. All I want to know is if I am dying because I have a virus or am I dying because I think that I am dying??? Because if this virus truly DOES NOT exist then I can go on believing that I am NOT dying… that would be awesome.
Listen, I am dying from illnesses resulting from an HIV infection that I
obtained directly after having sexual intercourse with a black chick
named Black Jackie. All I want to know is if I am dying because I have a
virus or am I dying because I think that I am dying??? Because if this
virus truly DOES NOT exist then I can go on believing that I am NOT
dying… that would be awesome.
Viruses exist there is no doubt. However, it the isolation and charcterization of the alleged pathogenic ones that is still in question and remains problematic. Although HIV has never been effectively isolated to date I do not deny that such a virus exists, but that remains to be scientifically proven – so far that is not the case.