Yes and yes.
Most microbes don’t affect us in any way.
And when they do affect us, of course, only then do we take notice of them. If smallus cantseeit in your backyard has no effect on humans, as indeed it likely won’t, no one will ever notice it or bother to study it. But if it starts killing people, scientists will become very interested in it indeed.
Who else is kinda disappointed in Randal Monroe for drawing a bacteriophage talking about infecting humans?
The microbiome is easy the ignore, tough to study, hard to study understand. At a minimum, without it you would have difficulties getting nitrates, fully digesting food, training your immune system, keeping your skin and body free from overgrowth by more dangerous microbes, getting enough vitamins and probably much more than we understand.
My understanding is that there are two types of viruses: those based on DNA (which replicate in the nucleus, except pox) and those based on RNA (which replicate in the cytoplasm, except flu and retroviruses). You probably recall DNA is the substance in cells which is a tightly coiled pair of strands that encode matching nucleotides to form the basis of genes and heredity. Perhaps you recall RNA is another substance which can have roles in transferring nucleotides or expressing encoded proteins.
In any case, all RNA viruses can mutate. DNA viruses often have proofreading, like your own cells, which corrects mutations and which occur much less frequently. You are correct that coronavirus is an RNA virus and so can mutate frequently. This can make a vaccine much more difficult.
DNA viruses include hepadna, herpes, adenovirus, pox, parvovirus, papilloma and polyoma. They are double stranded (except parvo). RNA viruses include polio (a picornavirus) with Salk and Sabin vaccines, measles and mumps (paramyxoviruses), retroviruses (HIV), rubella (a togavirus), rabies (rhabdovirus), and others (reo, hepe, calici, flavi, corona, orthomyxo (flu), filo, arena, bunya, delta, etc). So lots of RNA viruses still have vaccines.
Yes, mutation is a form of evolution. This is one characteristic of living things, but there are many others. See post 14.
The goal of vaccines is to create antibodies against the virus. Corona is challenging because the antibodies in cured people are not permanent. In general, vaccines can be live and attenuated (measles, mumps, rubella, yellow fever, nasal flu, chickenpox VZV, Sabin polio). Or killed viruses - rabies, injected flu, Salk Polio, Hep A - which induce humoral immunity. Subunit vaccines are used for Hep B and papilloma. But this is more detail than you probably want.
Actually, more complicated than that. (See my earlier link to the Baltimore classification.) There are double-stranded DNA viruses, single stranded DNA viruses, double-stranded RNA viruses, single-stranded positive sense RNA viruses, and single-stranded negative sense RNA viruses. (No known single-stranded negative sense DNA viruses–yet.)
I read an article years ago discussing the behavior of viruses. It stuck with me because of the idea that viruses are not alive but have some innate “intelligence”. We know that the purpose of a virus is to reproduce. They used an example of the behavior of the Spanish Flu. In crowded conditions, the virus had the opportunity to jump from host to host and killed quickly. In less crowded conditions, the virus killed more slowly. It was as if the virus could recognize that it had it achieved its purpose, had moved to a new host and no longer needed the original host. I always wondered how the virus “knew” that had happened.
It also talked about the common cold which has evolved to make people just sick enough to feel bad but not sick enough to keep people from going about their lives and spreading the virus. It’s been highly successful in circulating continuously by behaving that way.
Sure. Viruses are complex and you could discuss strands, capsules, directions, shapes, families, all sorts of stuff. In medicine, the idea is often to take complex subjects and explain them as simply as possible. I didn’t do that well, but you don’t want to oversimplify and I thought (probably wrongly) additional details might be of interest. I was trying to answer a question, but don’t know if it was understood or even if the asker has flown the coop.
Viruses can sometimes “recognize” attachments on a target but not sure how well this is understood - suspect that researchers see the attachment so know it’s possible (eg the ACE2 in coronavirus four times as “strong” an attachment as SARS in upper respiratory epithelium?), but not much more?
England had a big research unit for decades dedicated to beating the common cold. They never did, obviously, and disbanded. Strains which don’t kill the host tend to eventually dominate. I think part of the strategy of social distancing is to hope the more lethal reactions die out. Unfortunately, I’m not sure if those are a different strain rather than people who don’t have “pristine lungs” overreacting while trying to fight off the infection.
There seems to be some misinterpretation here. Viruses (not virii, unless there is a Celtic tribe by the name that I am previously unaware of) will form so-called colloidal crystals or more properly monodisperse arrays, which was and remains a very useful property for identifying them via x-ray crystallography, which is arguably [POST=18712034]the most important scientific tool ever invented[/POST]. This has nothing to do with the persistence of viruses under certain conditions like freezing cold, which is more due to the fact that they do not have to maintain any kind of metabolic processes.
Not really. While there is no absolute definition of the line between “living” and “not living”, there are certainly minimum criteria in living systems which includes consumption, metabolism, and procreation. Virions don’t do any of this except in the environment of a living cell where the RNA or DNA genome of the virus is replicated by the machinery of the cell, and the capsid is produced in a similar fashion. However, some virologists have a different definition of virus in which the virions (the genome and capsid particle) is simply the reproductive element and the virus is actually the living cell that has has been modified to generate virions. Under this paradigm, the virus-as-cell is certainly alive and just reproduces in a unique way rather than via mitosis or binary fission, but this is not the standard definition in virology.
Because it has not yet been referenced, I highly recommend reading Carl Zimmer’s A Planet of Viruses, which is a short (~120 page) but fascinating read on viruses. Viruses are indeed “profoundly strange” to an extent I don’t think we even fully appreciate, and their effects on evolution are only starting to be understood.
Stranger
I saw a TED talk that discussed issues like this. It comes down to evolution.
I don’t recall all the details as it was years ago, but the jist was basically that there is a tradeoff in lethality and infectivity. A pathogenic microbe that reproduces too fast kills its host before it can move onto a new target. So from the viruses point of view, it wants to reproduce as much and fast as possible, but not so fast that it kills its host before it can find new hosts. Depending on the circumstances of the host, it naturally evolves towards one or the other.
However pathogens that are spread by vectors like insects get around this, because a person can be laying in bed and still be a vector for transmission. With a lot of infections you need to be healthy enough to socialize, get to the water supply, touch things in communal areas, etc to spread the disease.
Also coronavirus gets around this because you are contagious for about ~5 days before you show symptoms.
I think it was this video.
And in the area of defining “life”, I’ll toss in Life As We Do Not Know It by Peter Douglas Ward.
Thanks, maybe I’ll check those out.
I read Zimmer’s short book on viruses. A good read, making some of the same points. But he says if you took all the viruses in the world’s ocean and stacked them end-to-end, they would reach 46 million light-years. You can give it a name, but really it’s a distance beyond comprehension. And I was impressed the DNA in one body, end-to-end, stretches into space. To Pluto. Since it is so skinny, you have more than a metre in each tiny cell of yours, and many billions of those.
It’s my understanding that in order to have the complexity of what DNA can do, viruses are inevitable. Upthread I wrote “biostatic”. It is; the DNA signal of life generates some noise and the noise can reproduce itself.