When a virus invades an animal, one assumes that the animal's immune system either kills the virus or the virus kills the animal. Either way, the virus dies. How do viruses survive this to live on? Question 2. Viruses apparently prefer cold because it allows them to spread further. How is it that they seem to like a human body with a temperature approaching or even exceeding 100 degrees?
A virus invades a human cell and causes that cell to create numerous duplicate viruses. A noted infection will have produced large numbers of viruses that end up being released by the human emitting those viruses through seezing, touching, etc. The human who fell ill may conquer the infection, but that individual will have had significant time to emit large numbers of very capable viruses into the environment. Also, viruses will have been emitted even if the infected person never reaches a point where symptoms are detected. So, it would be possitlbe to become infected even if the person who gave it to you never has notable symptoms. With COVID, the individual will be emitting those viruses in large numbers for at least a couple weeks before symptoms emerge. So, staying away from those who have symptoms is NOT good enough. Viruses stay in the air longer in dry air conditions. Cold air is dryer. When it's humid, the droplets of mositure from human breathing tend to grow larger and fall out of the air faster, somewhat reducing the likelihood that someone will breathe them in. Winter encourages closer contact as people stay indoors, etc. As we keep hearing with COVID, social separation is important for reducing the chances of becoming infected by a virus. Air temperature isn't as important except that cold air can't carry near as much moisture. I don't know how viruses respond to body heat. But, it sure doesn't seem to pose a problem for them! Check me out. I'm no doctor!
They're like parasites. They keep finding new hosts. However, if they're too powerful then the Virus will also die out. The Virus has to find a middle ground. I dont know
I seem to recall reading that over time evolutionary pressure forces diseases and their hosts towards towards a compromise. It is not actually in a disease's (especially viruses) interest to kill it's host but rather leave it alive so that later generations/strains can potentially reinfect that same host again. At the same time hosts that fight off a disease better than other members of their species tend to pass on their genes. The result is that (assuming continued exposure) as generations progress later generations of the disease tend to become less virulent. There is an evolutionary advantage in being less/non-lethal. The Flu virus is a master of this process and lots of bacteria we carry on our bodies today for instance with no ill effect (and some that are even beneficial) would have been disease causing when they were first encountered.
It's an ongoing battle with the immune system. From an evolutionary standpoint, viruses do not want to immediately kill the host. That would not be the most advantageous for their continued existence and reproduction.
1.) Before the virus dies it is transferred to another host. 2.) I believe the direct sunlight kills the virus - not the temperature. Now I will go check my own answers ... '
Somewhat related, leprosy thrives in armadillos for the same reason it attacks human extremities. The armadillo is one of few mammals, with a relatively low, core temp.
The problem here is that I didn't ask the question to provide a quiz for the group. They are honest questions for which I am seeking an answer out of curiosity. Apparently there aren't any virologists on the forum. I'm not one either. Thanks for the responses.
You seem to be operating from a premise that a virus is life, ie., and organism like a germ. It's not. But, when in doubt, ask a virologist.
Untreated, Rabies, Ebola, HIV and others have mortality rates about 70% - with Rabies being close to 100%. People die from Ebola pretty darn quickly. No vaccine has been created for many of the killer viruses - for example, there has been no vaccine for any of the viruses in the SARS family (including the one causing COVID19, obviously). We modify vaccines for flu quite rapidly, but we've had reasonably effective flu vaccines for years. This newer virus is in a different category. Some of the vaccines for dangerous viruses have required decades to develop and produce. We haven't rid the world of any of the top ten viruses that kill. They all still exist and are evolving. There are several different strains of Ebola, for example, with the Sudan varient being particularly fast and deadly - with 80% mortality. Plus, there are plenty of viruses in the animal world that could at some time cross to humans. This is important as it is CRYSTAL CLEAR that the human population is open to endemics of new and existing viruses - yet we have done little to nothing to take action until one swamps us. In 2016, Obama created a team to prepare for response to naural or manmade pandemic in the USA. Trump killed that effort in 2018. We need to make SURE that this time we maintain a group that is working to make us ready - somewhat like FEMA does for natural disasters (though the steps would be different, of course).
I had this debate on another thread somewhere. Were viruses 'living' or not. The debate went on a bit but the according to someone with a background in biology the consensus was that viruses were a 'form' of life i.e. albeit they required very specific environmental conditions (i.e. the nucleus of another living cell) in which to 'live/reproduce.
I'm not so sure replication equal life, is it not a certainty that, if they haven't already, the day will come when they invent a machine that will be able to replicate itself? Here are two microbiologists arguing for and against, that point: Apparently it's an unsettled question https://microbiologysociety.org/pub...e/article/are-viruses-alive-what-is-life.html Not that it makes a difference more than a point of curiosity, given they can wreak havoc on humans and animals, but still, it's not a settled verdict. What all of them do seem to agree on is this: Whether or not viruses are 'alive' depends on how you define life That is the big kahuna, no one really knows what life actually is, and isn't. And that makes a lot more sense.
To my knowledge, there is only one exception: Smallpox. It killed millions and fortunately it is gone now (except for a few refrigerated samples). That was probably the greatest achievement of the WHO. We like to categorize. Life is merely one such category. You can describe precisely how viruses spread, reproduce or mutate, but where you draw the line between life and non-life is based on an arbitrary definition.
A virus is little more than a capsule that is equipped to penetrate certain cell types and a strand of genetic material that it can inject. To replicate, it has to land on an appropriate cell type and inject its strand of genetic material. Then, that invaded cell creates more viruses. So, one certainly can say that a virus can not reproduce itself. It has none of the machinery for any of the various methods of reporduction that involve only its own kind. It has to hope someone sneezes or rubs it off on your clothes and then you breath it in or rub your eyes or something. Then, it can float around and maybe land on a good victim cell.
To you perhaps but it makes perfect sense Would you say the same thing about a parasite that cannot reproduce without a host? That is very common in parasites. Parasites can be worms or amoebas or insects or even plants, or any number of other living things.
Interesting point.. I would say that "parasitic" is a descriptor that only applies to how the organism gets energy. It doesn't describe anything about reproduction.
True. However, the term parasite refers to how they get their energy, not the environmental requirements they may have for procreation. The thing about a virus is that it has no machinery for procreation. I'm not really sure how much it matters whether a virus is considered alive. It may come down to which answer makes it easiest to talk about life forms without having to say "except viruses" over and over.
