Virus, as an infectious microbe consisting of a segment of nucleic acid (either DNA or RNA) surrounded by a protein coat, can be found in any corner where life exists on the earth.
Viruses rely on other organisms to survive and reproduce. Although they are just a piece of genetic material wrapped in a protective protein shell, their impact on life on earth is far beyond imagination.
At least 8% of human DNA comes from the remnants of ancient viruses that may have infected our ancestors at some point, but eventually incorporated some of their genetic material into human DNA. In addition to "modifying" organisms at the genetic level, they also affect the behavior of organisms in the short term.
Humans originated in Africa, and by about 15,000 years ago they had spread to all continents except Antarctica by migration, but what drove the migration?
One possibility is that as populations grow, people are forced to move for resources, but the other is to escape infectious diseases, or in some cases viruses.
In fact, humans are hard-wired to fear and avoid infectious diseases. Sometimes we even fear innocuous things that seem to cause disease.
Now, we've built cities, we've kept the bad stuff outside the cities, but we're not free of viruses, and COVID-19 is the best example of that.
If all living things have natural enemies, those at the top of the food chain, including humans, probably do so by viruses.
In 1918, during World War I, the Spanish flu swept the world in a short time. It was the first worldwide pandemic and the most severe in human history.
Some estimates suggest that the pandemic may have killed more than 100 million people at a time when the global population was only 1.7 billion.
However, the direct and indirect death toll of the World War I was about 16 million, which was far less than the damage caused by the virus. In terms of lethality, it is fair to say that the virus is the natural enemy of mankind.
We know that infectious diseases can be caused by bacteria or fungi in addition to viruses, but why are viruses the only ones so difficult to control?
Why Is It So Hard to Find Drugs to Kill the Virus?
There are a lot of drugs on the market for bacterial infections, but it's hard to find specific drugs for viral infections, because viruses are actually harder to fight than microbes like bacteria.
Bacteria are independent life forms that are structurally similar to our cells and can survive without host, but they also have many characteristics that humans don't have.
And because of that, we can develop antiseptic drugs based on these characteristics that we don't have.
Source: Mrjohncummin
Penicillin, for example, works because it interferes with the construction of the bacterial cell wall, but no cell in the human body has a cell wall, so penicillin can inhibit the growth of bacteria but it can't affect human cells.
Unlike bacteria, viruses cannot reproduce ("replicate" would be a better term) independently outside their host cells, they need to hijack the host cell as a place to live and reproduce.
It is clear that viruses are no match for bacteria in terms of their ability to survive independently, or even at all.
But their relationship with the host cell makes it difficult to kill them alone and keep the host cell alive.
Since many viruses do not directly kill cells after entering cells, but enter the incubation period, where they slowly replicate inside the cell and then quietly leak out and infect other cells.
So, there are antiviral drugs that can control the infection of viruses by interfering with their replication, but unfortunately most of the time they also inhibit the replication process of host cells, in other words they are also toxic to the infected person.
In fact, the more dependent the virus is on the host cell, the more difficult it is for antiviral drugs to work.
In addition, viruses are not classified as simple as bacteria. There are many similarities between different bacteria, but different viruses are incredibly different, which means that it is difficult to find a specific drug that can fight many viruses.
Does the Virus Have Natural Enemies?
In fact, there are only short-term benefits to using drugs against bacteria. The bacteria will continue to develop resistance and eventually the drugs will become ineffective. So the use of antibiotics has been criticized and many people worry about the generation of super bacteria.
Fortunately, however, there is a more plausible solution, that is biological control. In other words, we can use the natural enemies of bacteria to control bacterial infection.
The only natural enemy that biologists have found to be useful are bacteriophages, which are essentially viruses that can infect bacteria.
Source: Guido4
Organisms have evolved to get rid of all kinds of natural enemies, but it's really hard to get rid of viruses, which are in a sense the natural enemies of all living things.
There are some viruses that can infect bacteria and inhibit the reproduction of bacteria, but have no effect on human beings. They are pure natural "antibacterial drugs", and basically have no side effects.
So could viral infections be handled in a similar way?
In short, viruses also have biological predators, but it is difficult to deal with their infections in a biologically controlled manner.
It's hard to call viruses life, but as we said, they do have protein coats and NDA, which means they're rich in phosphorus and nitrogen, which are nutrients for a lot of living things.
So many protocelled organisms have been found to "prey on" viruses, but mostly on the phages we mentioned earlier.
However, there is a virus that can infect other viruses, and these viruses are called virophage. Virophages are the same as the phages we mentioned earlier, and they use other viruses to replicate and affect the replication of other viruses.
But it's also hard to think of them as antivirals, because these virophages only infect giant viruses, and they're rarely found for viruses that aren't very big.
Conclusion
Everything in the world is mutually reinforce and neutralize each other. Although viruses disguise themselves as if they are not even living, there are still living things that will prey on them, but their infection is really difficult to deal with because of their relationship with the host cell.