How viruses invade cells, and how viruses infect cells: 5 steps

After the virus enters the cell, it first disintegrates by itself, releasing a very active RNA molecular chain, because there are many free nucleotide molecules in the cell, such as guanine, adenine, etc., so RNA uses these molecules to synthesize its own DNA, and then combine it into a virus to complete reproduction. Cells also resist viruses, such as a cold, which is the body's cellular response to viruses. However, some viruses also have a strong anti-resistance ability, once it disintegrates first, the response of the cells is not good, because the cells resist the invaders at the cellular level, and it is difficult to resist at the molecular level.

Immunity is based on humoral immunity and cellular immunity.

All are done outside the cell.

When the virus invades the body, there are effector B cells that produce antibodies.

Rendering a virus or bacteria inactive (so-called virulence).

When the live bacteria invade the cell, T lymphocytes produce effector T cells, which rupture the entire cell, causing the virus or bacteria to explode, and the effector B cells deal with it.

In fact, the immunity in the human body is still very strong, but the time from the invasion of the virus to the reaction and clearance is still quite long.

And then there's the overuse of antibiotics, which makes viruses or bacteria more resistant to antibiotics. That is why sometimes the effect of taking medicine and injections after a cold is not obvious.

Virus infects cells, including adsorption, injection, synthesis, assembly, and release. The tail spine of the virus is combined with the cell, and after fixation, the middle column tube is inserted into the cell to release the genetic material into the cell, and at the same time, the viral shell falls off, and the genetic material usually binds to the nucleic acid of the host cell, making the cell unable to recognize, and the viral nucleic acid is again the protein and nucleic acid and some skeleton substances required to synthesize itself, reaching the mature stage, the virus is assembled in the cell, and finally the cell is lysed from the inside out.

Because the binding of viral nucleic acid to the host cell inhibits the synthesis of cellular DNA, the cell does not synthesize its own DNA.

The body's immunity is divided into three lines of defense:

First line of defense: **, mucous membranes.

The second line of defense: bactericidal substances in body fluids, phagocytic cells.

The third line of defense: specific immunity.

Among them, the first and second lines of defense are called "non-specific immunity", which are mainly to resist the direct invasion of external foreign bodies, and the bactericidal substances and phagocytic cells kill and absorb (just simply absorb into the phagocytic cells) foreign bodies.

The third line of defense is "specific immunity", which has a targeted nature and plays a very important role in the body's resistance to the harmful invasion of external viruses, which can be divided into three stages: 1 Induction stage. This involves phagocytes exposing the epitope of an antigen (you can think of an antigen as a virus) and presenting it to lymphoid T cells.

2 Reaction phase. T cells should be differentiated by T cells and memory cells, B cells should be differentiated by B cells, and effector B cells should produce antibodies. 3 Phases of effect.

Lytic baba cells (the hiding place of the virus), T cells and effector T cells secrete lymphokines, antibodies bind specifically to the virus, and phagocytic cells engulf lysed cell residues.

The above shows that the body has carried out active and efficient defense measures against external intruders such as viruses.

However, it takes a certain amount of time for the three phases of the body's specific immunity to proceed, which causes the spread of the virus.

The replication of the virus is simply divided into the following processes:1 Adsorption The virus adsorbs on the cell surface.

2 Inject your own DNA or RNA into the target cells.

3 Replication The injected DNA or RNA uses free nucleotides in the cytoplasm to replicate (different viruses replicate in different ways and cycles) to form daughter DNA or RNA. On the other hand, the injected DNA or RNA forms mRNA through transcription (RNA is first reverse transcribed into DNA), the translation of mRNA forms proteins or polypeptides, and the proteins and polypeptides further form mature proteins (the capsid of the virus).

4 Assembling The capsid and the genetic material of the offspring are assembled into complete offspring (the number of offspring formed is different depending on the environment and its own conditions).

5 Release Release Release the progeny virus.

First the viral infection touches all normal somatic cells, then the viral infected casing binds to the cell wall of all normal somatic cells (there are glycoproteins on top), and then the viral infection introduces its genetic material into all normal somatic cells, and uses the copies of the material of all normal somatic cells (copies of genetic material and protein shell) in it, and then the genetic material of the viral infection and its casing are assembled in all normal somatic cells, and finally breaks through all normal somatic cells (all normal cells die) and returns to the outside of somatic cells. Such a circulatory system.

A virus is a microscopic, simple structure, and contains only one nucleotide.

DNA or RNA), which must be non-somatic microorganisms that parasitize and reproduce by copying.

Although biological viruses can have certain benefits for humans, such as the use of bacteriophages.

Able to heal some bacterial infections; The use of insect viruses can cure and prevent some agricultural and animal husbandry diseases, but they are quite harmful, such as HIV and rabies.

etc., at risk to human life; Cold virus, hepatitis B.

The virus will produce symptoms; TMV, potato Y virus causes economic losses to people. A virus is a subtle microorganism that can spread between other plants and infect the plant body (in fact, the virus cannot carry out basal metabolism due to the infection itself).

Therefore, in a sense, it cannot be said that viruses are living things).

Sometimes the term "viral infection" is used to describe these microorganisms that spread and infect eukaryotes; Apply the term "bacteriophage" or "phagosome" to describe these in prokaryotes.

Microorganisms that are interspersal. The origin of the virus is not very clear.

There are five steps:

Adorption: The protein shell of the virus relies on a small hook at the tail to adsorb to the surface of host cells such as bacteria.

Injection: The virus's own genetic material is injected into the host cell.

Replication synthesis: Using the material and structure of the host cell, under the guidance of the viral genetic material, the viral protein is synthesized, and the genetic material of the virus is replicated at the same time.

Assembly: The genetic material and protein shell of viral replication are assembled together to form numerous daughter viruses in the host cell.

Release: The nutrients of the host cell are used by the daughter virus, the host cell disintegrates, and the daughter virus is released. Oh no!

Hope it helps.

First, the virus comes into contact with normal cells, then the outer shell of the virus fuses with the cell wall of the normal cell (which has glycoproteins on it), then the virus injects its genetic material into the normal cell, and uses the material of the normal cell to achieve replication (replication of the genetic material and protein shell), then the genetic material of the virus and its outer shell are assembled in the normal cell, and finally breaks through the normal cell (normal cell death) and returns to the outside of the cell, and so on.

A virus is a small, simple non-cellular organism that contains only one nucleic acid (DNA or RNA) and must parasitize and replicate in living cells.

Sogou asked. Extended Materials.

Although biological viruses will bring certain benefits to humans, such as the use of bacteriophages can ** some bacterial infections; The use of insect viruses can prevent some agricultural pests and diseases, but they are very harmful, such as HIV, rabies virus, etc., which bring danger to human life; Influenza viruses, hepatitis viruses, etc. can bring diseases; TMV, potato Y virus causes property damage to people.

A virus is a tiny organism that can spread from one organism to another and infect an organism (in fact, because the virus itself cannot be metabolized, it cannot be said that a virus is a living organism to some extent).

The term "virus" is sometimes used to describe those organisms that circulate and infect eukaryotes; The term "phage" or "phagosome" is used to describe those organisms that spread between prokaryotes.

Viruses enter host cells in different ways: injectable invasion, endocytosis, membrane fusion, and other specialized invasion methods.

Injection invasion: generally the invasion method of tailed phages. The DNA genome within the capsid is injected into the host cell by tail contraction.

Endocytosis: a common mode of invasion of animal viruses. Invagination through the cell membrane forms phagocytic vacuoles, allowing virions to enter the cytoplasm.

Membrane fusion: The viral envelope fuses with the cell membrane during the invasion of an enveloped virus.

Direct invasion: It can be broadly divided into three types.

Some virions directly invade host cells, and the mechanism is unknown.

After the virus binds to the receptor on the cell membrane surface, the enzymes on the cell surface help the virionian release nucleic acid into the cytoplasm, and the viral capsid remains outside the cell membrane, integrating the virus invasion and uncoating.

Other special ways. Plant viruses invade cells through small wounds or natural pores on the plant cell wall, or through plasmodesmata between plant cells, and can also invade cells through the mouthparts and suckers of mediators.

According to the different species of the virus, the protein derivatives on the surface of the virus specifically or non-specifically bind to the lipoproteins or glycoproteins on the cell membrane of the target cells, and the protein derivatives of the latter side open a certain signaling pathway, release channel proteins, inhibit the local inactivation of the protein activity on the surface of the cell membrane of the target cells, and open the transfer channel.

First, the virus comes into contact with normal cells, and then the outer shell of the virus fuses with the cell wall of the normal cell (which has glycoproteins on it), and then the virus injects its genetic material into the normal cell, and uses the material of the normal cell to achieve replication (copying the genetic material and protein shell).

2. On the other hand, the genetic material infiltrates the inside of the target cell through the material transport channel of the target cell, and then integrates with the DNA of the target cell, replicates the genetic material and protein shell in the target cell, and releases it when the cell dies and circulates again. Individual viruses can even enter cells through pinocytosis of target cells.

How does the virus enter cells?

How do viruses invade cells? To put it simply, there can be 4 ways.

After the virus invades and lodges, the first step is to express a protein associated with replication, called the latency. The second step is to express structural proteins, such as coat proteins, and use replicase to replicate a large number of nucleic acids, which is the growth phase. The third step is assembly, where nucleic acids and structural proteins are assembled to form virions that can be transported into other uninfected cells.

Extended information: First, it is adsorbed on the surface of the host cell and combines with the cell surface after passing through the cell membrane into the cell, and under the action of lysosomal enzymes, the capsid protein is removed to release viral nucleic acid, and the nucleic acid is released into the cell, then it enters the biosynthesis stage of the virus, including viral nucleic acid replication and gene expression, and finally the viral nucleic acid and protein are synthesized and assembled into mature viral particles in the cytoplasm or nucleus.

To put it more simply, these are the following: adsorption, penetration, unshelling, biosynthesis, assembly, maturation and release.

Virus is a relatively simple organism, it only has genetic material and protein shell composition, that is to say, it has no way to rely on its own to copy and synthesize genetic material (there is no organelle with relevant functions), therefore, the virus invades the cell is a major progress in evolution, by entering the cell, using the relevant substances and energy in the cell, to complete the synthesis and assembly of its own substance, the virus can reproduce.