Which kind brother and sister told me about the virus?

A virus is a tiny microorganism, which can only be seen with an electron microscope. The virus has a simple structure, belongs to a cell-free microorganism, and consists of a genetic material nucleic acid and an outer protein shell. Viruses cannot live independently, but must live in the living cells of other organisms to grow and reproduce.

Viruses are widely distributed in nature, and people, animals, insects, plants, fungi and bacteria can all be infected by viruses. Virus is one of the important pathogens that cause human infectious diseases. In human infectious diseases, viruses are far more than bacteria and other microorganisms, accounting for about 3/4, such as influenza, hepatitis, epidemic hemorrhagic fever, chickenpox, herpes zoster, AIDS and so on. The virus is also associated with some tumors, congenital malformations and Alzheimer's disease.

There are many kinds of viruses, which can be divided into animal viruses, plant viruses and bacterial viruses according to different hosts. According to the clinical and infection routes, it can be divided into respiratory tract infection virus, digestive tract infection virus, hepatitis virus, Japanese encephalitis virus, nerve virus, sexually transmitted virus and so on. Different viruses have different modes of transmission and pathogenic characteristics after invading human body, some only cause local infection, and some can spread with blood or nerves.

The virus has an incubation period from infection to onset, and the shortest is only 1 ~ 3 days, such as influenza virus; Older people can last for months or even years, such as rabies virus.

Most people can develop immunity after being infected with the virus, but the duration is different.

Viruses can directly invade the skin and cause skin damage, and a few of them can cause skin allergic reactions and rashes due to the antigenicity of viruses. Due to different pathogenic viruses, their clinical manifestations are also different, and viral dermatoses are generally divided into three types in clinic:

(1) Blister lesions are mainly blisters. Common are herpes simplex, herpes zoster, chickenpox, herpetic eczema and so on.

(2) Neobiotype skin lesions are verrucous. There are various common warts (common wart, plantar wart, flat wart, condyloma acuminatum, molluscum contagiosum, etc. ).

(3) The eruptive lesions are erythema or papules. Common are measles, rubella and acute rash in children.

Parvovirus is a kind of microorganism without cell structure, but with life characteristics such as heredity and self-replication. They are the smallest creatures. Pure virus is a beautiful crystal, you can't see its vitality at all, but once it is combined with cells, you will immediately know how vicious it is. Viruses are much smaller than bacteria. Before the virus was discovered, the first person to find life smaller than bacteria was American young scholar Ricky. 1909, when studying typhus, a pathogenic microorganism was found. In memory of others, this creature is called Rickettsia. A year later, this outstanding young man who was only 39 years old died of typhus. Compared with the real virus, rickettsia is very large, although it is much smaller than bacteria. From the later review, we now know that the first person to see this virus was the Scottish doctor Buster. He saw the vaccinia virus, which is the biggest virus. This happened on 1887. The person who can clearly see the basic shape and structure of the virus is American astronomer Williams, who invented the projection method to let people really see the true face of the virus, while Finn Vilska used the low-speed electron microscope to let people see the fine structure of the virus. The appearance of virus

There is a joke that goes like this. A teacher asked a student what cowhide was for, and a student replied that it was used to wrap cows. In fact, this is very correct. Any living thing seems to have a shell or something, and most viruses are no exception. Their shell is protein, and they are a kind of nucleic acid. Someone once peeled off the shell of one virus and replaced it with another protein, but the virus after reproduction was the same as the original one. This shows that protein shell is not the decisive factor of virus, but it can prevent the nucleic acid inside from being destroyed by external chemical or physical effects. Of course there are exceptions. For example, potato virus has no shell. More extreme is the scrapie virus of sheep, which has no nucleic acid at all, but only an "inhibitor" that can turn substances in other cells, including genes, into its own appearance. It may be the smallest virus in the world. Recently, a scientist cultivated a human ear in a mouse, which should be said to be inspired by some kind. This is very important. If the cost of cultivation can be reduced to a very low level, the life span of human beings may be more than doubled. But then again, if our world is basically the world of the elderly, it will be really boring. Don't be angry with your old friends:-) Now briefly talk about the structure of the virus: it is like a light bulb, the glass part is protein shell, and the filament part is evil nucleic acid!

Now let's look at how viruses survive. Figure 5 on the right is a typical virus. The tadpole-shaped protein shell is wrapped with spiral nucleic acid, and the tentacles under it are called tail filaments, which are responsible for contacting cells or bacteria. Figure 1 shows that the virus contacts a cell with its tail filament; Fig. 2 shows the injection of viral nucleic acid into cells; Fig. 3 shows that the new virus has been replicated; Figure 4 shows that the cells decompose and release a new number of viruses. Needless to say, that poor cell is completely finished. No one likes catching a cold unless he finds it more painful to study and work. If so, he can sweat first and then take a bath with cold water immediately. If possible, find someone who has caught a cold and breathe deeply into him when he sneezes. Next, you can rest assured to write a leave note … because at this time, countless cells in your body began to be so ravaged by the cold virus. In other words, many animal viruses must work at a certain temperature. When the body temperature drops, the drug-resistant cells in the body stop or basically stop working, and the virus has an opportunity. t4 phage

Phage feeds on bacteria or actinomycetes.

The last page shows a famous experiment in microbiology. The virus in the picture is a guy called phage. The picture on the left shows its true face under the electron microscope. The virus is parasitic, and its target is all living things except itself. Generally speaking, the virus has only one kind of nucleic acid, which can only proliferate in one kind of cell. Viruses can cause diseases of animals and plants, sometimes with very serious consequences. For example, smallpox virus, which has ravaged the earth for hundreds of millions of years, has claimed countless lives. My guess is that it may cause more deaths than malaria. However, some viruses can also serve us, such as killing pests and harmful bacteria. The picture on the right shows hepatitis virus. I didn't expect it to have such a wonderful structure, did I

Main epidemic viral infectious diseases:

Viral hepatitis

infantile paralysis

Viral gastroenteritis

Enterovirus infection

flu

measles

chickenpox

Infectious mononucleosis

epidemic parotitis

epidemic encephalitis B

Forest encephalitis

epidemic haemorrhagic fever

dengue

rabies

AIDS

General characteristics of viruses

Virus is a kind of acellular microorganism. The main features are as follows: (1) is small, and can pass through sterilization filter, and most viruses can only be seen by electron microscope; (2) There is only one type of nucleic acid, DNA or RNA；; (3) strict replication and proliferation in living cells (eukaryotic or prokaryotic cells); (4) It has receptor binding protein, which binds to virus receptor on the surface of sensitive cells, and then infects cells. The main differences between viruses and other microorganisms are shown in Table 2 1- 1.

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