1. Why does removing the lipid layer destroy the virus if most viruses don't have one in the first place?
2. How can soap be effective against "most viruses" (as the article claims) if only "some viruses" (as wikipedia claims) have a lipid layer?
3. Why doesn't TFA mention the capsid at all? I would have thought it should be on the diagram at least.
Edit: A simpler explanation that doesn't have these problems and agrees with all the facts I know is that soap destroys proteins, which is what viruses are made out of. See https://www.quora.com/How-do-detergents-denature-proteins
1. Viruses that don't have an envelope have evolved to survive without the envelope. Viruses that do have an envelope haven't. Are you confused that removing a crab's exoskeleton kills it, given that there are lots of animals that don't have exoskeletons?
2. This is probably just sloppy usage of "some" and "most". That said, i think enveloped viruses are overrepresented amongst viruses that cause serious disease in humans, because the envelope helps them evade the immune system.
3. Some viruses don't have a capsid [1]! Coronaviruses do, though, so that's just missing from that diagram.
4. Surfactants like soaps do disrupt protein, but typically not as effectively as they disrupt lipid bilayers. There are numerous techniques in biochemistry and cell biology that depend on this fact - permeabilising cells for immunocytochemistry, or preparing membrane proteins for crystallisation, for example. You have to boil proteins in powerful detergents to be sure of denaturing them.
The article is about "most" viruses, and according to him, "most" viruses don't have a lipid layer, so I think it's a fair criticism, unless what he said is factually incorrect.
You're reasoning from first principles in contradiction of statements of scientific fact that are being communicated to you, however imperfectly. Resolving the contradictions in your own understanding does not constitute a proof. The simplest explanation is that you do not yet correctly understand and that you need further information.
The point of science communication isn't stamp collecting random disconnected facts. It's to give people mental models that they can use to answer questions. If this information is so half-baked and imperfect that you can't make a basic inference from it, then it's not good science communication.
> The soap dissolves the fat membrane and the virus falls apart like a house of cards and "dies", or rather, we should say it becomes inactive as viruses aren’t really alive.
I always presumed that viruses, similar to other microorganisms, are alive. Until reading the above quote, I had never considered the idea there was any question about this. I was intrigued by the concept that they many not really be alive so looked up the Wikipedia article [1] which says that
> Viruses are considered by some to be a life form, because they carry genetic material, reproduce, and evolve through natural selection, although they lack key characteristics (such as cell structure) that are generally considered necessary to count as life. Because they possess some but not all such qualities, viruses have been described as "organisms at the edge of life", and as replicators.
One of the Wikipedia references is Are viruses alive? The replicator paradigm sheds decisive light on an old but misguided question [2] which looks at different replication mechanisms as a continuum rather than a simple “life vs non-life” dichotomy.
As a biochemist, i think it's absolutely clear that viruses are not alive, because they don't do anything. No metabolism, no signalling, no changes in structure, no use of energy or materials. They just float about! It's only when they encounter a cell that anything happens, and then it's mostly the cell's machinery doing it.
If i was a molecular biologist, i would probably think it was absolutely clear that viruses are alive, because they contain a genome, and proteins encoded by the genome, and they use the proteins to make more copies of the genome. What else is life?
I'm of the opinion that whether something is alive or not is arbitrary, and depends on your definition. Humans just came up with the word to describe a class of things.
You could define biological life in a way that includes or excludes viruses, I would suggest, and be right either way.
(Also if a biological virus is alive, is a computer virus alive? It's self-replicating and has DNA in the form of code.)
This is the key point I think: viruses have no metabolism. There is no stable energy transfer with their environment. Their genomic feedback does not promote metabolic growth (ie greater energy transmission rates).
I work with some groups trying to build synthetic cells, and honestly there isn’t even a good definition for what a “cell” is or what “life” is in the scientific communities. The best proxy I can come up with, which is universally true on earth, is that life is anything that fully encodes ribosomes and can replicate (there aren’t any discovered exceptions to that yet, though some are close). Very intellectually unsatisfying, but so far factually true for anything generally considered “living”.
Evolution/competition between ribosome encoding and capsid encoding organisms[1] has driven a lot of cool stuff to be developed: for example, bacteria and archaea (+ eukaryotes) gained DNA separately (presumably from viral infection) and retroviruses enables placentas.
I would also add t-RNA[1] to that list. It can almost replicate by itself, and sits right in the middle between "data" (DNA/RNA) and "code" (a small machine that can selectively hold an amino acid)
>> viruses [...] are alive. Until reading the above quote, I had never considered the idea there was any question about this.
> in the scientific communities
"Is it alive? <long property checklist> Yes/No" is an example of K-12 science education content diverging from science community practice. Both by emphasizing a little used concept, and by being inconsistent with community use.
With bonus points for it being... widely taught; taught as if it were science; an unnecessary hook for learning a set of properties; and an incoherently unfruitful predicate.
I don't know if there's a real name for such? I call them science-education-isms.
I’d love to connect with you. I’ve been developing a discrete time control systems model of the central dogma as a signal processor of environmental EM radiation (eg heat).
True, but ultimately of no consequence to the discussion in hand. Nothing we say or do is of consequence to the universe, but they matter to us. Ultimately, these lines are drawn for our benefit, not the universe's.
In my highschool biology class (that makes me an expert... right? :) ) The definition of life included self replication and, IIRC, having some sort of metabolism. The reason my biology book classified viruses as not alive is simply because they are incapable of self replication and they don't really have a metabolism to speak of (Old viruses are still infectious).
Virus behave like life in some ways. They're made out of the building blocks of life, and are indeed subject to evolution. But they don't absorb nutrients and don't reproduce themselves. They are created by the cells they infect.
But it's a thin line, and it depends on which definition you want to use.
I have come to view them (from a programer's sense) kinda like functions and stateless services compared to living life which is like classes and other state-y things. It can change classes, it can be mutated and overridden, but does not think or act on its self, it must be interacted with.
I, for one, as a human being whose root ancestors¹ infected planet Earth² which eventually produced me³, am will to use a definition that qualifies viruses as very much alive. ;-)
____
Tangentially related, I sympathize with Earth parasite Musk who wishes for us to infect another cell— err, I mean, planet. Shoosh, Earth, back to sleep, nothing to see here...
____
[1]: I wonder who's the chicken, here. Certainly, the virus is the egg, right? It's all a plan to engineer the actual masters of this universe?
[2]: A long, long time ago...
[3]: Well, the 10% of my weight with my DNA. I feel more like an ecosystem, I am a legion of species, a myriad DNAs, we are millions in those guts. "I" is not even the same "I" when travelling to a different biome: you are what you eat, quite literally, however you want to spin that idea.
If viruses are on the edge of alive, then books and posters might be too, in some sense.
Virus's are "life" without replication machinery. And what is a book but a similar sort of dormant form, without the fertile replication machinery of the [human] mind to remix it and help its ideas fuck with other ideas. This view of viruses and words as life perhaps isn't as wrong as it first sounds, and some linguists on the fringes argue that language is more like a semiotic symbiont that has "moved into" our biology, specifically our neural structures, like a creature moving into an ecological niche and modifying it to suit its purposes. Or as I prefer to think about it: maybe we're already cyborgs straddling structures of biology and semiotics. (See: The Leiden School of Language[1]).
Maybe humans are just the first example of this language portion of our organism starting to venture cautiously outside of our biology, like astronauts exploring outside spaceship corpus ;) Reality might be pretty weird imho, and hard to see for what it truly is.
A kind of concerning thought: who's to say there aren't higher-level versions of this same concept playing out? Say we figure out the nature of consciousness and are able to effectively interact with it's "thinginess." Then we find: there are things in our universe that're semi-conscious, but feed and replicate on/inside/with the consciousness of others and are incapable of existing on their own.
In Icelandic the word for life is "líf", there is also another word "eilíf" which is concatenated from "ei" meaning "not" and "líf" meaning "life". This word means "eternal".
Therefore: The definition of life is "not eternal" (if you assume the law of excluded middle - actually the definition of "eternal" is "not life" :)
What I'd like to understand is why viruses are less prevalent in the summer due to more humid air, but yet they can exist in the moist body and spread from moist spray from coughs / sneezes.
I haven't been able to phrase the question just right to find the answer to what seems like a conflict.
I think the spray is just a method of transmission with the virus "hoping" to dry out quickly on a dry surface before it falls apart.
This paper confirms the finding (google search: droplet transmission "winter"). They're uncertain of the mechanistic cause, though. They summarize:
> Cold and/or dry conditions impact the stability of influenza virus particles, the innate defense of host nasal epithelia, and the production of infectious bioaerosols. Each of these effects contributes a plausible explanation for the impact of [relative humidity] and temperature on respiratory droplet transmission, and more than one mechanism most likely contributes to the observed transmission outcomes.
Heat, humidity and sunlight all reduce infections during summer.
Humidity seems to reduce infection multiple ways.
1. Testing shows that there is less virus particles in air after it has been humidified. Stuff like droplets, dust and micro-particles fall down faster.
2. In dry air viruses may have more direct way into lungs and other tissues when the protective moist layer is evaporating away.
> Testing shows that there is less virus particles in air after it has been humidified. Stuff like droplets, dust and micro-particles fall down faster.
Seems feasible but can you provide a citation? Thanks!
My personal theory is that in places like England in the winter people close the windows and cough at each other hence spreading colds, flus etc. In the summer they open the windows, go outside, the cough outputs blow away. I was recently in Bali and Singapore and noticed no colds in Bali where everything is outdoor and transport is mostly scooters and a lot in Singapore where everyone sits in aircon boxes - offices, busses etc. Also there's a fair bit of coronavirus in Singapore and not much it seems in Bali in spite of Bali having many Chinese tourists.
I don't know the impact factor of these journals, and a bit too lazy to look up, but it's probably a very complex problem, otherwise it'd be settled by now.
A 2018 study claims that it's independent of humidity, but their 2019 one seems to show a trend with absolute humidity.
so this explains why 20 seconds, if anyone would explain that at the first place and not just say out of the air wash for 20 seconds I would remember the motivation and understand and do that otherwise I forget what I do not understand. So typical of the shallow news not to explain.
Some people, like you and I, do better with the explanation. Some people, like my grandma, get bored about a syllable and a half into the explanation and just want to hear the rule. I agree that both should be accommodated, but I suspect that the large majority case is people who are okay with the high-level presentation.
Some people simply want to be told "what" to do. They don't care about "why".
Others wish to understand "why" they are being told to do "that". These folks are typically on the science/engineering side of the spectrum.
Unfortunately, the "tell me what" population group size seems to widely outnumber the "tell me why" population group size, so most "reports/directives" from authority accommodate only the "tell me what" group, leaving those of us in the "why" category wondering "ok.... and just 'why' do you want me to do that?"
Correct... the article does not explicitly mention the 20-second recommendation, which was presumably arrived at by experimentation. But it does explain why such a time-based recommendation might work:
> The skin is quite rough and wrinkly which is why you do need a fair amount of rubbing and soaking to ensure the soap reaches very crook and nanny on the skin surface that could be hiding active viruses.
The other way to think about it is the difference between 'clean' and 'sterile'; having no influential chemicals present (clean), and having no living units capable of replication present (sterile). They are actually different concepts that are caught up in the generic concept of 'clean'.
A surface full of massacred microorganisms might be 'sterile' - nothing there can support life, even if given sugar, water, energy, etc. But it's also certainly not clean. If any of the debris from those dead microorganisms could trigger your immune system, were poisonous, or were chemically active they could alter the outcome of a chemistry experiment or trigger an immune response.
Disinfectants by definition kill organisms, but don't remove the constituent components of the organisms from the area. Bleach & alcohol in high concentrations (but not pure!) will also destroy most any organisms (but will not in itself remove the debris of those dead organisms).
Soaps will link chemicals and molecules to water that is flowed over them, and will remove all of those constituent components along with the water. And if the soap is strong enough, it will also dissolve and destroy smaller organisms in the process. A surface washed with soap will no longer have any debris on it.
I've always heard a different explanation from the one in the article: that the soap isn't actually killing many viruses or bacterial cells, but rather just getting them off your hands and down the drain so you're less likely to infect yourself when you inevitably touch your face (I assume I'm not the only one who has been discovering this week just how hard it is to not touch your face). Is that not correct?
I think that's the case with bacteria, and maybe viruses that are put together in a different way. But from what I understand, these particular viruses are particularly vulnerable to soap.
Readit News
Wikipedia says "Some viruses are enveloped, meaning that the capsid is coated with a lipid membrane" - https://en.wikipedia.org/wiki/Capsid
I find the article confusing:
1. Why does removing the lipid layer destroy the virus if most viruses don't have one in the first place?
2. How can soap be effective against "most viruses" (as the article claims) if only "some viruses" (as wikipedia claims) have a lipid layer?
3. Why doesn't TFA mention the capsid at all? I would have thought it should be on the diagram at least.
Edit: A simpler explanation that doesn't have these problems and agrees with all the facts I know is that soap destroys proteins, which is what viruses are made out of. See https://www.quora.com/How-do-detergents-denature-proteins
2. This is probably just sloppy usage of "some" and "most". That said, i think enveloped viruses are overrepresented amongst viruses that cause serious disease in humans, because the envelope helps them evade the immune system.
3. Some viruses don't have a capsid [1]! Coronaviruses do, though, so that's just missing from that diagram.
4. Surfactants like soaps do disrupt protein, but typically not as effectively as they disrupt lipid bilayers. There are numerous techniques in biochemistry and cell biology that depend on this fact - permeabilising cells for immunocytochemistry, or preparing membrane proteins for crystallisation, for example. You have to boil proteins in powerful detergents to be sure of denaturing them.
[1] http://www.virology.ws/2010/09/23/a-new-type-of-enveloped-vi...
I always presumed that viruses, similar to other microorganisms, are alive. Until reading the above quote, I had never considered the idea there was any question about this. I was intrigued by the concept that they many not really be alive so looked up the Wikipedia article [1] which says that
> Viruses are considered by some to be a life form, because they carry genetic material, reproduce, and evolve through natural selection, although they lack key characteristics (such as cell structure) that are generally considered necessary to count as life. Because they possess some but not all such qualities, viruses have been described as "organisms at the edge of life", and as replicators.
One of the Wikipedia references is Are viruses alive? The replicator paradigm sheds decisive light on an old but misguided question [2] which looks at different replication mechanisms as a continuum rather than a simple “life vs non-life” dichotomy.
[1] https://en.wikipedia.org/wiki/Virus
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5406846/
If i was a molecular biologist, i would probably think it was absolutely clear that viruses are alive, because they contain a genome, and proteins encoded by the genome, and they use the proteins to make more copies of the genome. What else is life?
You could define biological life in a way that includes or excludes viruses, I would suggest, and be right either way.
(Also if a biological virus is alive, is a computer virus alive? It's self-replicating and has DNA in the form of code.)
Fundamentally life is a thermodynamic machine. Takes energy and converts a portion of it to 'work'.
Under homeostatic control. There are feedback systems that maintain the integrity of the organism.
In theory has a way of reproducing. This more applies to the species as a whole. Since individuals incapable of reproducing are none the less alive.
Viruses only meet the last and weaker criteria in my book.
Evolution/competition between ribosome encoding and capsid encoding organisms[1] has driven a lot of cool stuff to be developed: for example, bacteria and archaea (+ eukaryotes) gained DNA separately (presumably from viral infection) and retroviruses enables placentas.
[1] https://www.ncbi.nlm.nih.gov/m/pubmed/19845628/
It is tremendously difficult, perhaps impossible.
[0] https://en.wikipedia.org/wiki/Virus_classification#Subviral_...
[1] https://en.wikipedia.org/wiki/Transfer_RNA
> in the scientific communities
"Is it alive? <long property checklist> Yes/No" is an example of K-12 science education content diverging from science community practice. Both by emphasizing a little used concept, and by being inconsistent with community use.
With bonus points for it being... widely taught; taught as if it were science; an unnecessary hook for learning a set of properties; and an incoherently unfruitful predicate.
I don't know if there's a real name for such? I call them science-education-isms.
But it's a thin line, and it depends on which definition you want to use.
____
Tangentially related, I sympathize with Earth parasite Musk who wishes for us to infect another cell— err, I mean, planet. Shoosh, Earth, back to sleep, nothing to see here...
____
[1]: I wonder who's the chicken, here. Certainly, the virus is the egg, right? It's all a plan to engineer the actual masters of this universe?
[2]: A long, long time ago...
[3]: Well, the 10% of my weight with my DNA. I feel more like an ecosystem, I am a legion of species, a myriad DNAs, we are millions in those guts. "I" is not even the same "I" when travelling to a different biome: you are what you eat, quite literally, however you want to spin that idea.
If viruses are on the edge of alive, then books and posters might be too, in some sense.
Virus's are "life" without replication machinery. And what is a book but a similar sort of dormant form, without the fertile replication machinery of the [human] mind to remix it and help its ideas fuck with other ideas. This view of viruses and words as life perhaps isn't as wrong as it first sounds, and some linguists on the fringes argue that language is more like a semiotic symbiont that has "moved into" our biology, specifically our neural structures, like a creature moving into an ecological niche and modifying it to suit its purposes. Or as I prefer to think about it: maybe we're already cyborgs straddling structures of biology and semiotics. (See: The Leiden School of Language[1]).
Maybe humans are just the first example of this language portion of our organism starting to venture cautiously outside of our biology, like astronauts exploring outside spaceship corpus ;) Reality might be pretty weird imho, and hard to see for what it truly is.
[1]: https://books.google.ca/books?hl=en&lr=&id=_ind5AbdQaAC&oi=f...
Maybe they actually are vastly superior to us and the hosts are just their air to breathe.
Therefore: The definition of life is "not eternal" (if you assume the law of excluded middle - actually the definition of "eternal" is "not life" :)
Deleted Comment
I haven't been able to phrase the question just right to find the answer to what seems like a conflict.
I think the spray is just a method of transmission with the virus "hoping" to dry out quickly on a dry surface before it falls apart.
But inside the body?
> Cold and/or dry conditions impact the stability of influenza virus particles, the innate defense of host nasal epithelia, and the production of infectious bioaerosols. Each of these effects contributes a plausible explanation for the impact of [relative humidity] and temperature on respiratory droplet transmission, and more than one mechanism most likely contributes to the observed transmission outcomes.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4097773/
Humidity seems to reduce infection multiple ways.
1. Testing shows that there is less virus particles in air after it has been humidified. Stuff like droplets, dust and micro-particles fall down faster.
2. In dry air viruses may have more direct way into lungs and other tissues when the protective moist layer is evaporating away.
Seems feasible but can you provide a citation? Thanks!
"The exact mechanism behind the seasonal nature of influenza outbreaks is unknown."
https://en.wikipedia.org/wiki/Flu_season#Cause
A 2018 study claims that it's independent of humidity, but their 2019 one seems to show a trend with absolute humidity.
[2018] https://www.health24.com/Medical/Flu/News/humidity-doesnt-sl...
https://academic.oup.com/jid/article/218/5/739/5025997
[2019] https://royalsocietypublishing.org/doi/full/10.1098/rsif.201...
Others wish to understand "why" they are being told to do "that". These folks are typically on the science/engineering side of the spectrum.
Unfortunately, the "tell me what" population group size seems to widely outnumber the "tell me why" population group size, so most "reports/directives" from authority accommodate only the "tell me what" group, leaving those of us in the "why" category wondering "ok.... and just 'why' do you want me to do that?"
The moment I know good reason for why I should be doing something, my resistance to doing so drops to near zero.
But most people/authorities only parrot the thing we should be doing, mostly because they don't really understand why.
Where? I've read the thread three times now and I still have missed the part about 20 seconds. Why not 10 or 30?
> The skin is quite rough and wrinkly which is why you do need a fair amount of rubbing and soaking to ensure the soap reaches very crook and nanny on the skin surface that could be hiding active viruses.
So long as you're not stripping away layers of skin, I don't see why 30 seconds wouldn't be better.
A surface full of massacred microorganisms might be 'sterile' - nothing there can support life, even if given sugar, water, energy, etc. But it's also certainly not clean. If any of the debris from those dead microorganisms could trigger your immune system, were poisonous, or were chemically active they could alter the outcome of a chemistry experiment or trigger an immune response.
Disinfectants by definition kill organisms, but don't remove the constituent components of the organisms from the area. Bleach & alcohol in high concentrations (but not pure!) will also destroy most any organisms (but will not in itself remove the debris of those dead organisms).
Soaps will link chemicals and molecules to water that is flowed over them, and will remove all of those constituent components along with the water. And if the soap is strong enough, it will also dissolve and destroy smaller organisms in the process. A surface washed with soap will no longer have any debris on it.
Original source: https://twitter.com/PalliThordarson/status/12365493051895971...