Since human beings were born on this planet, we have been dealing with viruses for at least 250,000 years. Smallpox, SARS, Ebola, new crown pneumonia... In this protracted war, the virus has constantly mutated, and every battle against the virus has prompted mankind to constantly update its "weapons".
Should the virus be wiped out, or should it coexist with it?
To defeat the virus, you must understand the virus.
They are very ancient-
appeared in the early stages of the origin of life, and are the oldest and most primitive "indigenous" on earth.
They are tiny-the
largest virus is only one ten thousandth the diameter of a hair.
They are very simple-
basically "genetic material (DNA or RNA) + protein shell" model.
They are very fragile-
unable to live independently, and need to find an ideal host to complete the reproduction and evolution. Once they leave the host, they are only waiting for death.
They are huge in number-
there are more than 1030 bacteriophages (viruses that infect bacteria) in the waters of the world alone. If they are lined up, the total length will reach 200 million light years.
They are everywhere-
wherever there is life on earth, there are viruses.
From the sea to the land, from plants to animals, from bacteria to fungi...even the human genome contains viral genome sequences.
Under normal circumstances, viruses only multiply and spread in specific types of hosts, and it is difficult to "migrate" from one host to another. However, when certain virus mutations accumulate to a certain extent, they can successfully cross the host species barrier, proliferate and continue to spread in the new host, causing the disease and death of the new host, which may lead to an epidemic.
For thousands of years, human beings have fallen in love with viruses and have been attacked by viruses again and again, and have defeated them again and again. But this will not stop, we know it will come again and again. I don't know when or where it will be.
Only as often as Kouzhi, the pillow is waiting.
Viruses, a shuddering term, are always closely associated with disease and death. For thousands of years, mankind has been facing the invasion of various viruses. Rabies virus, influenza virus, SARS virus, new crown pneumonia virus... these names that often appear in the news are closely related to our lives.
However, imagine what the earth would be like without a virus?
The result is not as clear as you think. In fact, we live in a world of viruses. There are so many types of viruses that are countless. In addition to the large number, the virus also has a significant impact. For life on earth, including humans, many viruses are not only harmless, but also bring evolutionary advantages.
Without the virus, it is difficult for us to survive; without the virus, we cannot get out of the primitive mud. For example, there are two segments of deoxyribonucleic acid (DNA) derived from viruses, and they are now camped in the genomes of humans and other primates. Surprisingly, without these two pieces of DNA, there would be no pregnancy. Even more surprising is that another type of viral DNA helps to pack and store memories. There are other genes from viruses that promote embryonic development, regulate the immune system, or fight cancer. Their significance is only just now known.
Facts have proved that viruses have also played a key role in triggering major evolution. If all the viruses are eliminated, the biodiversity of the earth will collapse suddenly, as if all the nails of the beautiful wooden house were suddenly torn down.
From unknown to discovered
To tell the battle between viruses and humans, it is really a story from a long, long time ago. How long can it be?
Archaeologists have unearthed Ramses V, who was mummified three thousand years ago. He still has traces of smallpox on his body. This is the first smallpox patient found in human history. Although the entanglement between viruses and humans has been around for a long time, it was not until the 19th century that people gradually came up with the concept of "virus", and the research on this pathogen gradually became clear.
In the late 19th century, on the tobacco farms in the Netherlands, a disease ravaged the crops in the fields. The living plants were devastated by the disease, leaving only pieces of dead tissues, and all the farm harvests turned into clouds and smoke. The poor Dutch farmer had to ask the young agricultural chemist Adolf Meyer. Meyer inoculated the diseased tobacco extract into healthy tobacco. A few weeks later, these healthy tobacco also suffered from the same disease, so It is proved that this is a contagious disease, and it is called tobacco mosaic disease.
As the "theory of bacterial pathogenicity" prevailed in the medical world at that time, the relationship between bacteria and infectious diseases could be verified through Koch's law. Koch's law was also the golden rule for studying the pathogens of infectious diseases at that time. Therefore, Meyer also wanted to find the pathogen of tobacco mosaic disease through Koch's law, but found that inoculating the bacteria isolated from the diseased tobacco extract on healthy plants did not make them suffer from tobacco mosaic disease. . Therefore, based on the results of the research at the time, he had no way to prove that tobacco mosaic disease is an infectious disease caused by bacterial infection.
Then, in 1892, Russian scientist Ivanovsky used the most advanced bacterial filter at the time to filter the diseased tobacco extract, and then used the filter to infect healthy tobacco, only to find that the extract after filtering out the bacteria was still infectious. Sex, so he speculated that it may be a toxin produced by bacteria or a very small bacteria that can pass through a bacterial filter that caused tobacco mosaic disease. It may be affected by the prevailing atmosphere at the time. Although Ivanovsky discovered this important scientific phenomenon, he still firmly believes that it is caused by bacteria.
In 1898, Bayerlink, a professor of microbiology in the Netherlands, also repeated the experiment of filtering tobacco extract with a bacterial filter and then infecting healthy tobacco. At that time, people could only observe microorganisms through an optical microscope, while Bayerlink used an optical microscope. No organisms were observed in the filtrate.
In order to further explore what is infective in the filtrate, he diluted the filtrate and then infected, and found that the infection of the diluted filtrate on healthy tobacco was not significantly different from that of the undiluted group, so he believed that it caused This infectious disease is definitely not an inanimate chemical substance, but an active substance with life.
Then he mixed the diseased tobacco filtrate with healthy tobacco filtrate or distilled water to infect healthy plants, and found that the symptoms of tobacco infection under these two infection conditions were the same, which showed that the pathogenic factors did not proliferate in the healthy tobacco filtrate. Thus he concluded that this pathogenic factor can only proliferate in cells.
Therefore, Bayerlink called this kind of pathogen that can pass through bacterial filters, is infectious, and can multiply in the body but cannot multiply outside the body as a virus. This is the beginning of the discovery of the virus by humans.
Later, people discovered more viruses, and they could even propagate the viruses by culturing some cells in a petri dish. But on the question of "what is a virus", scientists still have their own opinions. Some people think that a virus is a chemical substance, and some people think that a virus is a parasitic organism of an organism. There is always no unified conclusion.
With the increase in the number of viruses discovered, some viruses could not pass through the bacterial filter due to their charge characteristics. The feature of "filterability" was finally abandoned. Thanks to the invention of the electron microscope, people can identify those with a certain size and shape. Virus particles, this undoubtedly provides the basic conditions for the investigation of the nature of the virus.
What exactly is a virus
At the beginning of the 20th century, a chemist named Wendell Stanley discovered that pepsin can destroy the infectivity of tobacco mosaic virus. He wondered: Is the essence of the virus a protein?
So he extracted the virus from tons of tobacco leaves infected with mosaic disease and crystallized the virus according to the method of purified enzymes. Then he stored the virus and ignored it. After several months, he dissolved it in water. The resulting liquid was still Has the ability to make healthy plants sick. So Stanley believed that a virus is a protein.
However, Stanley still made a mistake. Scientists Fred Bowden and Norman Pirie from the United Kingdom found that the purified tobacco mosaic virus contains a considerable amount of sulfur and phosphorus, and these two elements are rarely found in proteins but exist in nucleic acids. In 1936, the two expressed their opinion that tobacco mosaic virus is a nucleoprotein. This conclusion attracted considerable attention in the virology community at that time, and then people carried out a lot of research and analysis on various viruses, and finally reached a consistent conclusion: viruses are composed of proteins and nucleic acids. In the following 10 years, through repeated experiments, people came to a more important conclusion: nucleic acid is the main body of virus infection, pathogenicity and replication.
Viruses are currently the smallest life unit discovered by humans. They must rely on host cells to carry out their own life activities. Its structure is very simple, usually composed of nucleic acid and protein shell (nucleocapsid), and some viruses are in the nucleocapsid. There will also be a coating on the outside of the shell. The life cycle of a virus includes: adsorption (the virus binds to the host cell surface receptor), invasion (the virus injects its own genetic material into the host cell), synthesis (the nucleic acid and protein of the virus are synthesized in the host cell), assembly and release ( Complete the assembly of the self-carrying virus particles in the host cell and release the cell).
With continuous research, people have discovered viroids and prions, viroids are an infectious single-stranded RNA, and prions are infectious proteins. The discovery of these two viruses has once again refreshed people. For the understanding of life, virus-like and prion proteins are the simplest forms of life currently known. More importantly, it was later discovered that prions were actually allosteric from a normal protein in animal brain tissue, so it can successfully escape the defense of the immune system, and at the same time, this diseased protein can also induce surrounding proteins. The normal protein is allosteric, which accelerates the pathological changes of the tissues. I believe that with the continuous exploration of scientists, we will learn more about the unknown knowledge of viruses and figure out their origins.
Where will the virus and mankind go
At the beginning of 2020, a piece of news attracted widespread attention: a scientist published a paper saying that evidence of the existence of ancient viruses was found in ice nucleus samples on the Tibetan Plateau in Tibet, 28 of which are new viruses. However, this is not the first time that people have found evidence of the existence of an ancient virus in a glacier. In fact, in 2014, a French scientific research team found it in a frozen soil sample collected in the Chukotka Autonomous Region in the Russian Far East. A new giant virus, the Siberian broadmouth virus, and this prehistoric virus has been sealed in the frozen soil of Siberia, Russia for more than 30,000 years. Scientists used the amoeba to carry out resurrection experiments on the virus and found that the virus was not only resurrected but the resurrected virus was still infectious and could kill the amoeba, but it was safe for humans.
Even so, we have to worry that if glaciers and permafrost melt due to climate warming, the virus contained in them will reawaken to a great risk to human health. This is also a warning to us that excessive development and utilization of nature will not only threaten the safety of other organisms, but will also harm mankind itself.
People are afraid of viruses because we have discovered that viruses can cause serious infectious diseases and endanger human health and development, but there are actually very few viruses that are really harmful to humans.
According to the classification of virus hosts, viruses can be divided into plant viruses, bacterial viruses, and animal viruses. As a member of animals, only a small portion of viruses can infect humans and spread from person to person, such as influenza Viruses, HIV, dengue fever, SARS virus, smallpox virus, etc., most of the other viruses will only live in specific hosts and will not endanger human health.
According to statistics by virologists, 75% of the viruses that can be transmitted from person to person are from other animals. Only in the process of human contact with these animals does the virus create the opportunity to invade the human body. . For example, HIV itself exists in chimpanzees, but it is not harmful to chimpanzees. In the contact between Africans and chimpanzees, HIV is infected, which makes AIDS spread all over the world; SARS virus spreads from bats to chimpanzees. Civet cats, and humans prey on civet cats, the virus spreads from civet cats to people, and finally causes the spread of SARS virus from person to person. We can find that viruses can coexist peacefully with the host in the natural host. It is our humans who kill wild animals that allow these viruses to cross species. They may not be able to adapt to the new living environment and have not found a suitable way to get along. , That's why infectious diseases are harmful to humans.
Perhaps we should maintain a distance from nature, maintain the balance of nature, and live peacefully with nature on the earth, so as to avoid the spread of the virus across species. For those viruses that spread between humans, perhaps we can see our future with the virus in the symbiosis of wild animals and viruses. After a long period of evolution and human domestication, perhaps the virus can also achieve mutually beneficial symbiosis with humans in the future. The state of balance.
Looking back on history, we can find that in the development of human civilization, there have always been viruses. Viruses have caused the raging of infectious diseases again and again, and humans have found ways to overcome diseases with wisdom time and time again. The confrontation of the virus is undoubtedly promoting the progress of human civilization.
We live on the earth with viruses and share the resources on the earth. It is inevitable that there will be some collisions. In the constant collisions, humans and viruses are learning and evolving. Maybe in the near future we will be able to coexist peacefully with viruses or even It's mutually beneficial symbiosis...
Why is the extended reading virus easy to mutate? What does virus mutation mean?
A virus is a very simple creature. Except for virus-like viruses, viruses can be said to be the simplest members of life. Its genetic code or genome is mainly concentrated on the nucleic acid chain, and any change in this nucleic acid chain will affect the characteristics of their offspring. In fact, the genome of the virus is not static during its propagation, but is automatically mutated all the time. Most of these mutations are fatal, and only a few survive. Since a virus has to multiply millions of times in a single infection, there is a chance of mutation. Therefore, from a population level, a virus is not genetically homologous, so the "species" of viruses are not taxonomic species in the strict sense, but should be called quasispecies. The natural mutation of the virus is very slow, but this mutation process can be accelerated by the stimulation of strong external factors.
Viral mutation reminds us that we should treat antiviral drugs rationally. Because the virus mutates very quickly, and humans cannot predict the mode and trend of virus mutation, they can only gradually understand its characteristics after the virus has spread, and then develop antiviral drugs (or vaccines) based on its characteristics.
When the virus undergoes new mutations, the originally effective antiviral drugs may become ineffective, and the human immune system will ultimately depend on the human immune system to kill the virus. Of course, there is no need to panic too much about the mutation of the virus. As humans' understanding of viruses continues to deepen, coupled with the improvement of life support technology, the mortality rate will continue to decrease. Ordinary people only need to remember: pay attention to protection and not relax, early diagnosis and treatment and early intervention.
