"virus" in my eyes

? In the process of human beings, apart from the separation of life and death brought about by natural laws, it is not war or natural disasters, but "viruses" that end human life. During this period of time, some statistics have been sloppy. In the recorded stage of mankind, "virus" incidents frequently occurred, such as smallpox, the Black Death (plague), Spanish flu, cholera ... Among them, smallpox virus has plagued human events for the longest time and claimed the most lives. The earliest record of smallpox in human history is 1500 BC, and it is very likely that the Pharaoh Ramses V of ancient Egypt was killed by smallpox. With the change of time and people's continuous understanding and struggle against smallpox virus, the World Health Organization successfully declared that smallpox virus had been completely eliminated by human beings on June 26th, 1979. So far, this is the only virus that has been completely eliminated by human beings and threatens human life. According to the data, more than 500 million people died of smallpox. The scar on the outside of the arm of a man in his forties is a sign of vaccination. 198 1 In March, the Ministry of Health issued a notice to cancel the nationwide vaccination. Therefore, after 90 s and 00 s, most of them have not been vaccinated with vaccinia vaccine, and the scars on their arms are not caused by vaccinia, but by BCG (BCG is used to prevent tuberculosis). Actually, "vaccinia" and "BCG" are also viruses. When inoculated into human body, most people will go through the process of swelling, pustule, pustule rupture and scabbing, and will form special scar marks after healing. Subjectively, this allows special viruses to multiply after entering the human body, so as to stimulate the human body to produce a series of substances that are harmful to smallpox virus or tuberculosis virus and beneficial to the human body. This substance is called "antibody" in medicine. Different individuals have different time to store and make antibodies. Some vaccines should be implanted in stages, and some vaccines will form antibodies for life once implanted.

? In the14th century, the second global plague epidemic occurred, which lasted for more than 70 years and spread to Europe, Asia, North Africa and other continents. Recently, several subsequent pandemics included the Italian Plague from 1629 to 163 1, the London Plague from 1665 to 1666, the Vienna Plague from 1679, and/kloc-. At that time, Britain and Italy were the most seriously ill, and the death toll was about 200 million. As for why it is called the "Black Death", it is probably because after people are infected with the plague, their skin will turn black because of subcutaneous bleeding, and black symbolizes depression, sadness and fear, so the plague is called the "Black Death". The origin, spread and process of these epidemics are still controversial, but their deadly forms seem to have disappeared in Europe in the18th century. Today, the plague has almost disappeared in North America and Europe, but it still appears in some parts of Asia and Africa. Most people susceptible to plague are considered to be malnourished and immunocompromised.

? 19 18 The outbreak of "Spanish flu" directly ended the process of the First World War. According to the reports at that time, the flu epidemic was first discovered in Fenston Barracks, Kansas, USA, and then appeared in Europe and even around the world. Interestingly, this flu epidemic did not originate in Spain. Why is it called "epidemic Spanish flu"? Some people think that at that time, because of the war of World War I, countries had strict control over the media; Only neutral Spain can report publicly, so people have the illusion that the Spanish epidemic is particularly serious. According to records, Spanish King Alfonso XIII was also infected with this disease. The epidemic can be simply divided into three waves. The first wave occurred in the spring of 19 18, and it was basically just an ordinary flu. The second wave occurred in the autumn of 19 18, with the highest mortality. The third wave occurred from the winter of 19 19 to the spring of 1920, during which 500 million people around the world were infected, causing 20 million to 50 million deaths and spreading to the Pacific islands and the Arctic. At that time, China also suffered from this flu. Until 1920, it was conservatively estimated that the number of infected people was about 9 million and the number of deaths was about 50,000. Either Chinese herbal medicine has played a role, or the temperature and climate factors in China. Later, many studies in western countries showed that China had the least number of deaths in the world. Strangely, by 1920, this terrible flu epidemic suddenly disappeared without any warning. And until today, the strain and source of Spanish influenza have not been really confirmed, and the susceptible population of the virus is young adults aged 20-35.

? The historical description of cholera can be traced back to the 5th century BC. Before19th century, cholera was only an endemic disease with a long history in India and Bangladesh. After entering the19th century, due to the appearance of ships, trains and emerging industrial cities, cholera began to wreak havoc around the world, and it was prevalent seven times worldwide, six of which occurred in the19th century, so it was also called "the world disease of19th century". Since 18 17, there have been seven worldwide epidemics, and the number of deaths cannot be counted. However, from the fact that the number of cholera deaths in India reached about 38 million in 100, it can be seen that the number of cholera deaths will never be lower than the above-mentioned infectious diseases, and may even be higher. Cholera is an acute diarrheal infectious disease, which is caused by food or water contaminated by Vibrio cholerae. Vibrio cholerae exists in water, and the most common cause of infection is eating water contaminated by patients' feces. Vibrio cholerae can produce cholera toxin and cause secretory diarrhea, even if it stops eating, it will continue to diarrhea. Washing rice-like feces is a feature of cholera. Cholera can be caused by many kinds of Vibrio cholerae, and the pathogenicity of each strain is different: some strains can cause more serious diseases, which can cause diarrhea, dehydration and death within hours. In recent years, in some underdeveloped areas, due to backward sanitary conditions and drinking water conditions, large-scale epidemics have occurred in some areas. An epidemic broke out in Zimbabwe in August 2008, spreading all over the country. According to MSF, the epidemic was not controlled until after the rainy season in March 2009. 20 10 A cholera epidemic broke out in Haiti in mid-June. By June 20 12, 7,000 people had died and 520,000 people were infected. 20 17 cholera broke out in Yemen, and more than 7 million people were threatened by the epidemic. Fortunately, although people have not completely eradicated cholera virus, the developed oral cholera vaccine can give people immunity for about half a year. The susceptible population of this virus is young children.

? In addition, there are many diseases that haunt us for a long time because of the existence of some "viruses", which are born with * * * and * * *. With the continuous development of scientific means, it will be possible to expand, understand and master the world's cognitive scope, and even eliminate a certain kind of "virus" again. The problem is that there is no quantitative basis for the "virus" on the earth, that is to say, human beings can never let the "virus" disappear forever in nature. The only thing they can do is to recognize and face rationally, change their lifestyle as much as possible, or enhance their immunity, or try to avoid being infected, so as to improve our quality of life, that is, to survive.

? What exactly is a virus? Is it a plant? Animals? Fungi? Or bacteria? What is its organizational structure? What does the virus live on?

? Today's biology roughly divides the substances that make up the world into two categories, biological and abiotic; The criterion of distinction is whether the substance can be metabolized (the generation and decomposition of chemical substances) and completely inherited. For example, people who eat steamed bread can be converted into "heat" through their own synthesis and can reproduce through sexual intercourse. People are planned in the biological camp. Plastics cannot be metabolized or inherited. It must be inanimate. What is a "virus"? Biological or abiotic? Don't worry, let's take a look at the composition and appearance of the virus first.

? "Viruses" are simple in composition, but have different shapes. They are all made of protein, and the protein is covered with the genetic material (nucleic acid molecules) of DNA or RNA. The diameter of most viruses is 10-300 nm, and the length of some filamentous viruses is 1400nm, but the width is only about 80nm (bacteria are generally about 0.5-5.0 microns). Viruses vary in shape, from helical icosahedral viruses to phages with more complex geometric structures. Most viruses cannot be observed under optical microscope, and virus particles can only be observed through scanning or transmission electron microscope. As for what is DNA and RNA? Simply put, DNA and RNA are units that record genetic information, which are broadly called genetic materials; The most obvious difference is that DNA is mostly double helix structure, while RNA is mostly single helix structure. Can the standards for judging organisms be used for metabolism? No, it cannot grow and replicate independently; However, viruses can replicate themselves by using host cell system through infection mechanism. Therefore, the mainstream view in network search is to define "virus" as "creature-like"; Understandably, unexpectedly.

? The first known virus is tobacco mosaic virus, which was discovered and named by artinus willem beijerinck in 1899. So far, more than 5000 viruses have been found. Perhaps, as biologists predicted, "Where there is life, there is virus; The virus may have existed when the first cell evolved. When the virus originated has been inconclusive, and it seems impossible to verify it, because the virus cannot form fossils and there is no external reference to study its evolution. However, the diversity of viruses shows that their evolution is likely to be multi-line, not single-line. It is worth noting that this virus seems to infect almost all organisms with cell structure. "According to people's cognition, there are relatively few genes that make up the virus. For example, influenza virus has only 8 genes, while rotavirus has only 1 1 genes. Perhaps because it has only a few genes, most viruses only attack specific organisms or biological tissues; When the virus successfully attaches through some channels, it will force the host cell to "simulate and recreate" thousands of offspring viruses. Even when two different viruses, or viruses from different generations of the same species infect the same cell, some genes may mix with each other and recombine into new types of viruses.

? How does the virus quickly complete the "simulated reconstruction" in the host cell? ?

? Attachment: A virus first binds to a specific molecule on the surface of a host cell. Because of the specificity of this binding, the virus can only infect several kinds of cells. For example, HIV can only infect human T cells, while plant viruses can only infect plants but not animals. The continuous evolution of this attachment mechanism will make the virus "fall in love" with the cells that enable it to replicate.

Entering the cell: After the virus adheres to the surface of the host cell, it enters the cell through endocytosis or membrane fusion.

Nucleic acid detachment: the virus releases the DNA or RNA it carries.

Synthesis: The synthesis system of the host cell will synthesize virus protein, virus DNA or RNA with the virus as a template according to the requirements of the virus.

Assembly: packaging the virus protein and virus DNA or RNA synthesized in the last step into hundreds of new virus particles.

Release: After the above steps are completed, the new virus will be released from the host cell. Most viruses will cause the host cells to dissolve and rupture in this process, while other viruses (such as HIV) will be released from the cells in a milder way such as budding.

? Can the virus easily invade the host and successfully complete the above steps without fear? The answer is no, of course. The human body has many innate ways to resist viruses. Some people are even indifferent. In other words, people's innate immune system can act on all viruses and "attack" invading viruses indiscriminately. For example, stomach acid can destroy many viruses swallowed into the digestive tract; Our human body will also produce a hormone called interferon, which will kill cells infected by the virus and neighboring cells to prevent the virus from "simulating reconstruction"; There are also enzymes in cells that can destroy viral RNA; In addition, some blood cells can directly devour cells infected by viruses. Unfortunately, this innate immune function does not seem to be enhanced after repeated exposure to the virus, nor does it have any "memory" of the virus that "fought". The lymphatic system in the human body will synthesize many special molecules according to the "memory" of the virus attached to the human body. These special components are often called "antibodies". These antibodies can be attached to the virus to prevent it from infecting the body's own cells. It's just that this antibody will be highly targeted and can only attack one virus. The lymphatic system of the human body can only be "passive defense, not active attack." That is to say, after the human body is infected by the virus, only when the speed of synthesizing antibodies in the human lymphatic system exceeds the speed of assembling new viruses with human cells, will the human body gradually repair damaged cells or tissues until they are cured, and the antibodies left in the human body usually have lifelong immunity to this virus. What is the relationship between the speed at which the human lymphatic system synthesizes antibodies? This question has not been able to find a convincing answer in the online world. I think faith is very important, followed by physical fitness and self-resistance. What else can there be? After all, people are still in the initial stage of exploring the mysteries of the human body. Who can assert that the human body's own means of fighting the virus is that simple?

? Viruses can spread in many ways, and each virus also has a specific mode of transmission. What is the route of transmission? It refers to the process that pathogens are discharged from the original host through a certain mode of transmission, reaching and invading the newly infected people. There are usually the following ways, and different viruses can spread through one or more of the following ways:

Droplet transmission: contact with secretions with pathogens (coughing or sneezing)

Direct transmission: contact with infected persons (including sexual contact)

Indirect transmission: contact with contaminated articles.

Airborne: contact with microorganisms living in the air.

Fecal transmission: contact with contaminated food or water.

Vector transmission: contact with vectors with pathogens.

Mother-to-child transmission

? Viruses such as influenza virus are mostly transmitted in the air through droplets produced when people sneeze or cough (aerosol transmission? )。 Cholera virus can be spread through feces, contaminated hands, food, water, etc. Will spread this virus. Rotavirus is usually transmitted through direct contact with infected children. HIV can be transmitted through sexual intercourse, because both parties will transfer body fluids during sexual intercourse. In addition, dengue virus can be transmitted by blood-sucking insects. Therefore, it is very important to know the transmission routes of various viruses to prevent virus infection and epidemic.

? Finally, talk about vaccines. At present, the most effective way for human beings to prevent viral diseases is vaccination. Vaccination is to control human beings to simulate natural infection without causing disease, so as to stimulate the spontaneous synthesis of antibodies in the lymphatic system, which has reached the ability of lifelong or staged immunity to a virus. Smallpox has been eradicated through universal vaccination According to statistics, the incidence and mortality of poliomyelitis, measles, rubella and mumps have decreased significantly in recent years. More than 13 kinds of human diseases caused by viruses have been inoculated, and more vaccines can prevent other animals from being infected with viruses.

? Since ancient times, we humans have never stopped exploring the unknown, and no one can predict the true appearance of the unknown world. What force leveled the crops and produced such a large area of geometric patterns? What's in 95% unexplored waters? What the hell happened to BIGBANG? Is there an alien civilization? There are too many things that we humans can't understand and recognize now. But, stop here? Obviously not. The driving force for human progress is the touch and exploration of the unknown world. Even if you encounter something that makes the gods cry, you should handle it well and handle it well. Attention, awe, distance. "Fate is in the sky, responsibility lies in people, and there must be a kind-hearted Qing Yu."

? I once saw a video, and the anchor left a bold and crazy assumption, "Does the virus promote biological variation like a scalpel?" (virus evolution theory? Ha ha ha ha, you can find more pictures of phage if you are interested. It's so fucking creative. Do you feel like a little robot Remember, isn't this sentence "the virus probably existed when the first cell evolved"? What time is it now? BIGBANG？ )