The structure of the virus particle of bacteriophage T4. Literature review

Bacteriophage T4 is a much more complex virus than VTM. Its two-welded DNA contains approximately 165 genes compared

Fig. 30.7. A VTM RNA section, which ensures the initiation of the assembly of the VTM virus particle.

Fig. 30.8. Electronic micrograph of partially reconstructed VTM particles. Two RNA tails separated from each growing virion are visible.

Fig. 30.9. VTM assembly scheme. A - the initiation area in the RNA forms a loop and passes into the central hole of the protein disk. The disc goes into the spiral shape of the "shut-off washer". In - to the end of the RNA, where the loop is located, new discs are joined. One of the ends of RNA is drained all the time through the central hole and interacts with new discs. Schematic representation of a RNA molecule in a partially assembled virus. The direction of the RNA movement is indicated by the arrow. (Butler P. J.g., Klug A., SCI.Amer., 1978.)

with 6 WTM genes. However, the structure, reproduction and the process of assembling the phage t4 are studied quite well, since it was subjected to intense genetic and biochemical analysis. Virion T4 consists of a head. Process and six threads (fibrils) process (Fig. 30.10). Its DNA molecule is tightly packed inside a ikosahedral protein shell and forms a virus head. The process consists of two coaxial tubes connected to the head of the short cervix. In the process, the contracting case surrounds the central rod through which the DNA is introduced into the host bacterium. The process carries at the end of a basal plate with six short teeth, from which six long thin threads depart.

The ends of the threads of the process are associated with certain areas on the E. coli cell. As a result of the AP-dependent reduction, the case pulls the phage head to the basal plate and the threads of the process, and as a result, the central rod penetrates through the cell wall, but not through the cell membrane. Then the nude phage DNA penetrates through the cell membrane. After a few minutes, all the synthesis reactions of cellular DNA, RNA and protein stop and the synthesis of viral macromolecules begin. In other words, the virus infected by the cell seizes the synthetic mechanisms of the bacterial cell and replaces its genes with its own.

In the DNA phage T4, there are three groups of genes that are transcribed at various stages of infection: prostrate, early and

Fig. 30.10. Electronic micrograph phage t4. (Williams R. S., Fisher N. W., An Electron Micrographic Atlas Of Viruses, S. S. Thomas, Springfield,

1974. Printed from the kind permission of the publisher.)

Table 30.2. (see Skan) Genes Faga T4

late. Prerepair and early genes are transcribed and broadcast before the DNA phage T4 is synthesized. Some proteins encoded by these genes provide the synthesis of cell macromolecules. Shortly after the DNA of the DNA host cell disintegrates under the action of deoxyribonuclease encoded by one of the early genes of the phage T4. DNA of the phage T4 itself is not hydrolyzed under the action of this enzyme, since there are no clusters (grouped residues) of cytosine. In the DNA phage T4 instead of cytosine, hydroxymethyl excitosis is located (GMC). In addition, the remains of the GMC in DNA T4 glucosylated.

These cytosine derivatives are included in T4 bacteriophage DNA due to the action of several phagospepic enzymes synthesized at the early stage of infection. One of them hydrolyzed DCTP to form DCMP to prevent the DCTP on Phag T4 DNA. Then the second enzyme introduces a hydroxymethyl group in DCMP, and forms

Hydroxymethylcytidial. The third enzyme turns -hydroxymethylcytidial into triphosphate, which serves as a substrate for DNA polymeraz. Finally, the fourth enzyme glycosylas some of the residues contained in DNA hydroxy methylcithosine.

The synthesis of late proteins is associated with the replication of the DNA phage t4. At this stage, the capsid and lysozyme proteins are formed. When the assembly of the visions of the offspring is complete, Lizozyme hydrolyzys the cell wall of the bacterium and destroys it. About 20 minutes after infection, there are about two hundred new viral particles.

Scientists have established how bacteriophage is striking the cell - the host by the ESHERICHIA Coli bacterium.

Researchers installed as bacteriophage T4 attacks host cell - Esherichia coli.

In the January issue "Nature", 2002 It is described how the virus uses a needle-like biochemical piercing device for infection of the E. coli host cell. "We have shown that this is a complex biochemical machine that allows the virus effecto to be embedded in the host cell. The base of the trunk of the virus plays a major role in this process, "says Michael Rossman from Purdue University.

Bacteriophage T4 is a real "Tyrannosaurus Rex" among viruses, so it best object For studies (the dimensions of it are about 100 nm in length and width). T4 is also a "stem virus", as it has a trunk with the processes attaching to it to capture bacteria. In 1 mm3 of ordinary water, there is usually around Billion Phages.

The T4 virus (see Fig. 1) consists of a ikosahedral head containing viral DNA, trunk, bases of trunk and stem processes - six long and six short. Long processes first find E. coli, and, then short firmly attached to the cell. The base in this case transmits the impulse into the barrel, which is reduced, as a muscle, squeezing with viral DNA into a host cell. The base of the virus is controlled by both the piercing device located in the barrel, and the enzyme, the cutting membrane of the E. coli cell.

This enzyme makes the hole of the nanometer sizes in the cell membrane through which the viral DNA enters the host cell. E. coli is thus infected and the biochemical cell machine produces new phage particles, and, in the end, the cell is dying. "To begin with, our study shows the structure of proteins that are part of the base near the barrel (the so-called biochemical piercing device), and their role in the penetration of viral DNA through the cell membrane," said Rossman.

In fig. 2 shows the structure of the base proteins, modeled using software "Spider". Data for the model was obtained in the study of 418 micrographs of frozen viral particles. The area indicated (GP27-GP5 * -GP5C) 3 is a biochemical piercing device. The greatest activity of the piercing enzyme is observed in the middle of the needle. Fig. a - stereo content of the base, rice. B - its molecular structure. 1 angstrom \u003d 1 / cm.

It was also found that when approaching the cell membrane, the base was deformed - it becomes like a flat star. This facilitates contact with the membrane and accompanies the introduction of "needles" into it.

Such studies are always associated with research in nanotechnology molecular production. On the basis of this knowledge, you can predict the appearance of high efficiency antibiotics.

T4 virus what it is

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Bacteriophages, or phages (from the ancient Greek - "Bacteria Eaters"), are viruses that can affect bacteria cells. They were open at the beginning of the last century, and already at that time scientists came to the conclusion that this virus could be an important means of fighting dangerous infections. It is thanks to these microorganisms that such severe diseases began to be treated as a bubonic plague and tuberculosis. Soon the antibiotics were opened, and the existence of the phages was safely forgotten. But today, the interest in these microorganisms of scientists is returned again.

Bacteriophages are the most numerous and very common, and perhaps the most ancient group of viruses. They were discovered for most bacteria, pathogenic, and also saprotrophic. In the nature of the phages are also found there, where there are bacteria sensitive to them: in soil and water, in the intestine of humans and animals, in plants, etc. The richer the substrate will be enriched with microorganisms, the much more bacteriophages will be more.

Model object - bacteriophages are very widely used for scientific research. Many fundamental discoveries in molecular biology It was precisely using bacteriophage that: genetic code, recombination and replication of nucleic acids. It is very easy to cultivate the most primitive biological methods and receive in very large quantities.

Bacteriophage T4 is a very convenient model object for the development of molecular biology methods and clarify the structural foundations of the virus infectiousness. Enterobacteriaphage T4 is one of the most studied viruses, bacteriophage, affecting the bacterium E. coli. It has a genomic DNA of about 169-170 thousand nucleotide pairs, packed in a ikosahedral head. The virion also has a trunk, base of trunk and stem processes - six long and six short. Enterobacteriaphage T4 is a major phage having a diameter of about 90 nm and about 200 nm. FAG T4 uses only a littic development cycle, but not a leased. Having considered the structure of bacteriophage, we found out that all known bacteriophages consist of two main components: proteins and nucleic acids. By type of nucleic acid, they are divided into DNA - and RNA-containing.

The bacal plate of bacteriophage is a complex molecular structure containing at least 15 different proteins that recognize the receptors on the surface of the host cells and carries out a structural restructuring of the tail of the virus necessary for cell infection. Using cryoelectronic microscopy, it was possible to reconstruct the three-dimensional structure of the basement of the phage.

The resulting structure has a shape of a tent with a sixth order symmetry relative to the longitudinal axis of the virus's tail, in the center of which is the molecular needle, which permeates the cell wall of the host during the infection process. The tail rod is attached to the top of the basal plate, which has a shape of a hollow tube, according to which DNA delivery of a virus DNA into a cell is carried out. Bacteria infection begins with the adsorption of phage, i.e. Attaching the tail of the bacteriophage to the cell surface. Adsorption is carried out by the fibrils of the tail process, which are attached to the structures of the bacterial cell, called the facoreceptors. Following the adsorption, the bazal tail tail of the bacteriophage comes into close contact with the cell wall, as a result of which the contractile cover of the tail is reduced, and its central stem pierces the cell membrane and is likely due to the reduction in the phage DNA head injects inside the bacterium. Bacteriophage immediately, after the penetration of DNA in the bacteria, genetic information recorded in the phage DNA begins to be implemented. In the case of T-even bacteriophages, enzymes that destroy the DNA bacteria are synthesized, and the enzymes needed for the reproduction of the phage DNA. After this stage, the synthesis of early proteins, the late proteins forming the bacteriophage shell are synthesized in the bacteria. As a result, new particles of bacteriophage appear, the bacterium is lysed, and the bacteriophage propagated in it goes into environment. If separate bacteriophages are applied to the surface of a solid nutrient medium with growing bacteria, then the bacteriophages spread in bacteria destroy the bacteria, forming the so-called "sterile spots" at this place.

Bacteriophages that can be reproduced in bacteria, destroy them and expect them in the form of full particles on Wednesday, are called virulent phages.

Along with such phages there are other - moderate phages. DNA of these phages after infection of the cell is introduced into the DNA of the bacteria themselves, without violating their livelihoods. It doubles and as a result is transmitted to the offspring. Bacteria, in the DNA of which there is a DNA of a moderate phage, is called a leased, and a phage DNA, combined with bacterial DNA, a contagon. If the leased bacterium is irradiated with ultraviolet light or treat chemical mutagens, then the transformation of the profhagus in phage, i.e., to initiate the reproduction of full phage particles in the bacterial cell, as a result of which the cell dies. Consequently, in the leased bacterium in the composition of a single bacterial chromosome coexist the genetic apparatus of bacteria with the virus gene, which is transmitted from the parent cell to offspring and can be activated (induced).

From this we can conclude that the phages are not only means against bacteria, but also the main assistant. It is bacteriophages that help to change bacteria, embedding their genetic material in its DNA. The development of new antibiotics is an extremely expensive and long process. But even the appearance of a new medicine does not guarantee that the microbes will not develop protection from it. These conditions force specialists to look for funds, which at the present stage can help with the treatment of bacterial infections and increase its effectiveness. Such drugs are currently called bacteriophages.

List of references:

1. Materials of the International Scientific and Practical Conference "Bacteriophages:

retic and practical aspects of application in medicine, veterinary and food

muslims "/ - Ulyanovsk: Ugzha them. P.A. Stolypin, 2013, t. IIU.

2. Rauthenstein Ya., Bacteriophagia, M., 1955

T4 virus. What is this virus? What diseases does it cause?

You are not mistaken? Maybe nevertheless not the virus? - more than a year ago

Bacteriophage T4 is one of the most studied viruses in the world. It affects enterobacteria, including intestinal wand, Salmonella and a plague wand.

This virus can become effective way Fight with dangerous infections. So the bacteriophage T4 does not cause any diseases, and even on the contrary, it helps to deal with them. With the help of the thread, the virus is attached to the cell of the pathogenic bacterium, the DNA of the virus falls into the cell, as a result of which it is destroyed.

In order for people to do not drink antibiotics, scientists synthesized medicines from natural bacteriophages to immunity.

Bacteriophages are a devourer of microbes in the body, cleaners.

In this case, the bacteriophage T4 devours the intestinal wand in infection and the person recovers without antibiotics.

The T4 virus is no longer so dangerous because all its features of development in the human body are revealed. Now, on the contrary, this virus is used as an assistant who washes to destroy the cells of bacteria.

Scary in appearance, but useful for a person, the T-4 virus is a bacteriophage, that is, affects enterobacteria. He is relatively large phage, it was studied by Nobel laureates, such as Salvador Luria, Alfred Hershey, Max Delbruck and others.

There is no danger to human health this virus, but only helps, devouring bacteria, as if sucking them.

The T4 virus is the most famous and studied bacteriophage, which devours bacteria. There is no disease, this virus has no disease, and even on the contrary, helps him fight bacteria. So it's not worth worrying about this virus.

This is what the T4 virus looks like in the photo taken with the electronic microscope.

There is such a long-known bacteriophage or FAG T4 - this is really a virus and he amazes, in one word devours bacteria and changes it, embedding its genetic material in DNA of this bacterium. Bacteriophages have long been known, since the beginning of the last century, and with the help of these interesting microorganisms, they found a cure for the bubonic plague, tuberculosis. When they opened antibiotics about these very interesting microorganisms forgotten and very in vain. Now scientists again took up the study of bacteriophages.

This virus is called T4 bacteriophage. Bantiofag is translated as a devourer of bacteria, that is, he lives in the body of bacteria and eats his master, due to what lives. For example, T4 eats an intestinal wand.

That is, this virus not only does not cause any diseases himself, but also helps a person fight dangerous diseases. T4 kills an intestinal wand, other bacteriophages eat tuberculosis sticks or even bacteria of the bubonic plague.

The T4 virus, called otherwise as bacteriophage, is hectares useful for a person with a virus and at the same time it is very well studied. This virus will help overcome the human body some infections: salmonella, intestinal sticks, etc. Very widely applicable in medicine. This virus devours harmful bacteria and helps to do without antibiotics.

Virus T4 or correct name of bacteriophage. What is it? Bacteriophages (phages) are a firus or if more accurate bacteria that devour the harmful bacteria. They replaced antibiotics, which strongly affect the human body, and bacteriophages are not harmful to the human body. In general, another development in the field of medicine, which will allow people to be refinery, as well as treat cancer, since bacteriophages are killed (sucking) bacteria that are in cancer cells. The history of the occurrence of bacteriophage (Virus T4)

Comments

With the help of its tail threads, the FAG is attached to the membrane of the bacterial cell, pierces it with its "tail" and like a microscopic syringe injects the cell inside the cell contained in its head.

The dramatic relations between the virus and the host cells are represented in fragmented form that the mechanism of protein synthesis, which usually flows in living cells. This is the finished "experimental device", the individual elements of which can be varied in one way or another. And attempts were made artificially reproduce the stages of this process in order to figure out how it happens.

FAG T4 has a value equal to 3 thousand angstroms (angstrom - one ten millionth fraction of a millimeter), but the structure of its particles is relatively complex, its DNA has up to 100 genes. For animals, this amount is negligible; For the virus it is already substantially. But let's start with an even simpler body - we are talking about one of the first viruses studied - tobacco mosaic virus (VTM). It is the same value as T4, but even simpler form. It looks like a cylinder whose width is only 150 angstrom. The axis of this cylinder passes the RNA thread. This RNA contains only 5 or 6 genes. The protein from which the cylinder is constructed consists of identical molecules. The protein molecule is formed from 5 or 6 chains, each of which contains approximately 150 amino acids. These chains are located double layer of the total thickness of 23 angstroms - in such a way that the sequences of molecules, inserting into each other in the form of spirals, create a cylinder body.

Mortal beauty of viruses

Imagination can sometimes be a little more colorful than reality. Or more terrible. And viral images, the image of which we often meet on the pages of books, magazines and newspapers, is exactly the case.

Mortal pathogens are illustrated in bright red, toxic-green or aggressive-orange tones. Ugly, terrible, almost weapons, they are just waiting to attack our body. In the ultimate goal, everything comes down to one - scare and render emotional influence, while the truth is that all viruses are transparent.

This fact made such a big impression on the artist from the UK Luke Jerram, which he used him as the main idea of \u200b\u200bhis new art project - three-dimensional glass sculptures "Glass MicrobioGy".

Luke Jerram was born in 1974 and graduated from the University of Wales in 1997 with honors from the first degree in fine art. He is an inventor, a researcher, an amateur scientist. The main idea of \u200b\u200ball his works is the study of space and perception. Personal view of the artist on viruses reflects a completely different image than a traditional idea that has formed in our consciousness. Its viruses are white and transparent, fragile and cold, but not terrible. Mysterious and majestic and, at the same time, more human than ever.

Among its exhibits, glass copies of the most fatal diseases for human diseases are: HIV, Ebola virus, bird flu, E. coli virus, Enterovirus type EV71, malaria, papilloma, swine flu, bacteriophage T4.

Each detail developed by Virusologist Andrew Davidson from the University of Bristol, exquisite reproduction of the virus. Although sculptures may seem exaggerated, with teeth, terrible bulbs, in fact they are created with amazing accuracy. Of course, they are much larger than their original appearance: glass viruses exceed the originals in size in a million times.

With the help of his creations, Jerram examines the relationship between the beauty of works of art and how they affect the person. Just as Susan umbrella speaks in his book "Illness and Its Metaphors" (illness and her metaphors), that art, like words, affects how we carry a disease. This means that you can cause fantasies regarding the disease, which are sometimes more dangerous and difficult than biological reality.

That is why the work of Luke Jerram is of great importance: it offers an alternative vision of a disease that can lead to another way to overcome it.

E. coli virus (intestinal wand)

The reactions to work were very amazing, "says Jerrars in his interview with the BBC channel, the sculptures are incredibly beautiful, and people attract it, but when they understand what, in fact, it is, it immediately appears a kind of repulsion item. Some feel as if they can get infected if they are touched them.

Enterovirus type EV71

Luke Creation is a challenge to our own ideas and ideas. They demonstrate that the reality and her perception is something completely subjective. In one of the letters published on the artist's website, anonymous author made recognition:

Your sculpture made HIV much more real to me than any photo or illustration that I have ever seen. This is a very strange feeling, seeing your enemy, which, ultimately, will be the cause of my death, and find it so beautiful.

FAG T4.

Bacteriophage T4 - one of the most studied viruses, bacteriophage affecting the bacterium E.

T4 bacteriophages uses a ring-type DNA polymerase; Its sliding cuff is a trimer similar to PCNA, but it does not have homology with NE with PCNA, nor with polymerase β.

T4 is a relatively large phage, has a diameter of about 90 nm and a length of about 200 nm. FAG T4 uses only a littic development cycle, but not a leased.

With Fagom T4 or similar bacteriophages, the laureates of the Nobel Prize Max Delbryuk, Salvador Luria, Alfred Hershei, James Watson and Francis Creek, as well as other famous scientists - Michael Rossmann, Vadim Meranzhinov, Fumio Arisaka, Seymour Benzer, Bruce Alberts.

T4 virus what it is

Growth and development. Viruses

Of the many known viruses, only individual representatives are presented in the scheme. All images are given with the same magnification. Viruses that breed only in bacteria are called bacteriophages (short: phages). The simplest structure has FAG M13 (1). It consists of one DNA single-liter molecule [ONDNA (SSDNA)] containing approximately 7000 N.O. (N.O. - nucleic base), surrounded by a protein shell of 2700 subunits packed in the helix. The virus sheath is called capsid And the structure as a whole - nucleocapsid. M13 is used in genetic engineering as a vector (see. P. 256).

FAG T4 (1), one of the largest viruses, has a more complex structure. The "head" of the virus contains bieting DNA [DNNNA (DSDNA)], number.

Pathogenic for plants The tobacco mosaic virus (2) is built similarly to M13, but instead of DNA contains onrNA (SSRNA). K RNA-containing viruses also includes polio virus (polyivirus), causing children's paralysis. GP virus nucleicapside has an additional shell Borrowed at the plasma membrane host cell (B). A virus proteins that participate and infected the host cells are fixed on the lipid shell.

B. Capesid Rinovirus

Rinovirus are pathogens of the so-called "colds". The capsid of this virus has a form ikosahedron Geometric shape, built of 20 equilateral triangles. The shell is formed from three different proteins located in the form of pentamers and hexamers.

B. Life cycle of human immunodeficiency virus (HIV)

AIDS virus (HIV) is known as the causative agent of the disease that is called name the syndrome of the acquired immunodeficiency (AIDS). In structural terms, HIV is similar to the influenza virus (A).

The HIV genome consists of two molecules of single-type RNA [ONRNA (SSRNA)], each molecule contains 9200 N.O.). The virus has a two-layer cap and is surrounded by a white-containing membrane. HIV infects mainly T-helper cells (see p. 286), which as a result can lead to the failure of the immune system.

In case of infection (1), the virus membrane merges with the plasma membrane of the target cell and the nucleus of the nucleocapside enters the cytoplasm (2). There, viral RNA (RNA) at first forms a RNA / DNA hybrid (3), and then transcribed to the formation of DNNNC (4). Both reactions are catalyzed by reverse transcriptase of the virus. The DNNNT is integrated into the cell (5) gene, where it may remain in an inactive state. When it is activated, a DNA fragment corresponding to the virus genome (6) is transcribed using the host cell enzymes. At the same time, replication is both viral ORNNA and MRNA (MRNA) encoding the precursors of viral proteins (7). Then the proteins are embedded in the plasma membrane of the cell (8, 9) and there are undergo proteolytic modification (10). The cycle ends with the reclamation of the newly formed viral particles (11).

The PHC-containing viruses, to which HIV belongs, is called retroviruses, since their life cycle begins with DNA synthesis on a RNA matrix, that is, from the process of reverse conventional transcription when the matrix serves DNA.

T4 virus what it is

Bacteriophage T4 is a much more complex virus than VTM. Its two-welded DNA contains approximately 165 genes compared

Fig. 30.7. A VTM RNA section, which ensures the initiation of the assembly of the VTM virus particle.

Fig. 30.8. Electronic micrograph of partially reconstructed VTM particles. Two RNA tails separated from each growing virion are visible.

Fig. 30.9. VTM assembly scheme. A - the initiation area in the RNA forms a loop and passes into the central hole of the protein disk. The disc goes into the spiral shape of the "shut-off washer". In - to the end of the RNA, where the loop is located, new discs are joined. One of the ends of RNA is drained all the time through the central hole and interacts with new discs. Schematic representation of a RNA molecule in a partially assembled virus. The direction of the RNA movement is indicated by the arrow. (Butler P. J.g., Klug A., SCI.Amer., 1978.)

with 6 WTM genes. However, the structure, reproduction and the process of assembling the phage t4 are studied quite well, since it was subjected to intense genetic and biochemical analysis. Virion T4 consists of a head. Process and six threads (fibrils) process (Fig. 30.10). Its DNA molecule is tightly packed inside a ikosahedral protein shell and forms a virus head. The process consists of two coaxial tubes connected to the head of the short cervix. In the process, the contracting case surrounds the central rod through which the DNA is introduced into the host bacterium. The process carries at the end of a basal plate with six short teeth, from which six long thin threads depart.

The ends of the threads of the process are associated with certain areas on the E. coli cell. As a result of the AP-dependent reduction, the case pulls the phage head to the basal plate and the threads of the process, and as a result, the central rod penetrates through the cell wall, but not through the cell membrane. Then the nude phage DNA penetrates through the cell membrane. After a few minutes, all the synthesis reactions of cellular DNA, RNA and protein stop and the synthesis of viral macromolecules begin. In other words, the virus infected by the cell seizes the synthetic mechanisms of the bacterial cell and replaces its genes with its own.

In the DNA phage T4, there are three groups of genes that are transcribed at various stages of infection: prostrate, early and

Fig. 30.10. Electronic micrograph phage t4. (Williams R. S., Fisher N. W., An Electron Micrographic Atlas Of Viruses, S. S. Thomas, Springfield,

1974. Printed from the kind permission of the publisher.)

Table 30.2. (see Skan) Genes Faga T4

late. Prerepair and early genes are transcribed and broadcast before the DNA phage T4 is synthesized. Some proteins encoded by these genes provide the synthesis of cell macromolecules. Shortly after the DNA of the DNA host cell disintegrates under the action of deoxyribonuclease encoded by one of the early genes of the phage T4. DNA of the phage T4 itself is not hydrolyzed under the action of this enzyme, since there are no clusters (grouped residues) of cytosine. In the DNA phage T4 instead of cytosine, hydroxymethyl excitosis is located (GMC). In addition, the remains of the GMC in DNA T4 glucosylated.

These cytosine derivatives are included in T4 bacteriophage DNA due to the action of several phagospepic enzymes synthesized at the early stage of infection. One of them hydrolyzed DCTP to form DCMP to prevent the DCTP on Phag T4 DNA. Then the second enzyme introduces a hydroxymethyl group in DCMP, and forms

Hydroxymethylcytidial. The third enzyme turns -hydroxymethylcytidial into triphosphate, which serves as a substrate for DNA polymeraz. Finally, the fourth enzyme glycosylas some of the residues contained in DNA hydroxy methylcithosine.

The synthesis of late proteins is associated with the replication of the DNA phage t4. At this stage, the capsid and lysozyme proteins are formed. When the assembly of the visions of the offspring is complete, Lizozyme hydrolyzys the cell wall of the bacterium and destroys it. About 20 minutes after infection, there are about two hundred new viral particles.

Some infections are asymptomagic or latent. With a latent infection, viral RNA or DNA is present in the cell, but does not cause disease, if trigger factors do not appear. Latence facilitates the spread of a virus from a person to a person. Herpesviruses show the latency property.

Hundreds of viruses can affect a person. Viruses that affect people are distributed mainly by the person themselves, mainly through the release of the respiratory tract and intestines, some - with sexual contact and when overflowing blood. Their spread among people is limited to congenital immunity acquired by natural or artificial immunity, sanitary and hygienic and other social activities, as well as chemoprophylaxis.

For many viruses, animals are served by the main owner, and the person is only secondary or random. The causative agents of zoonoses, in contrast to specific human viruses, are limited to geographically, those conditions in which the natural cycle of infection is maintained without the participation of a person (the presence of appropriate vertebrates, arthropods or those and others).

Oncogenic properties of a number of animal viruses are well studied. Human T-lymphotropic type 1 viruses are associated with some leukemia and lymphomas, the Epstein-Barr virus causes malignant neoplasms, such as NazyFaring's carcinoma, African Lymphoma of Berkitt, lymphoma in the recipients of transplanted organs that have received immunosuppressants. Hepatitis B and C predispose to the development of hepatocarcinoma. Herpes Humus Herpes of the 8th type predisposes to the development of the sarcoma of the capos, the primary discharge of lymphoma (body cavity lymphoma) and Castlemaker's disease (lymphoproliferative disorders).

The long-term incubation period characteristic of some viral infections gave ground for the term "slow viruses". A number of chronic degenerative diseases of the previously unknown etiology are now related to slow viral infections. Among them, we note the subacute sclerosing pankenefalitis (measles virus), progressing red-friendly pankenephalitis and progressive multi-grade leicoentephalopathy (JC viruses). Creitzfeld-Jacob's disease and spongy encephalopathy have signs similar to slow viral infections, but are caused by prions.

Diagnostics

Only a few viral diseases, such as measles, rubella, roseola newborns, infectious erythema, influenza and chickenpox can be diagnosed on the basis of only clinical picture and epidemiological data.

It should be remembered that accurate diagnosis is necessary when specific treatment is required or when an infectious agent represents a potential threat to society (for example, atypical pneumonia, SARS).

Fast diagnosis is possible in specially equipped virological laboratories by cultivation, PCR, determining viral antigens. Can help electronic (not light) microscopy. For a number of rare diseases (for example, rabies, oriental horsepower encephalitis, etc.) there are specialized laboratories (centers).

Prevention and treatment

Progress in the use of viral preparations is very fast. Antivirus chemotherapy is aimed at various phases of viral replication. They can affect the attachment of the particle to the membrane of the host cells or prevent the release of virus nucleic acids, inhibit the cell receptor or the factors of viral replication, block specific viral enzymes and proteins necessary for the replication of the virus, but not affecting the metabolism of the host cell. Most often, antiviral drugs are used in therapeutic and preventive purposes against herpesviruses (including cytomegalovirus), respiratory viruses, and HIV. However, individual drugs are effective against many types of viruses, for example, medicines against HIV are used in the treatment of hepatitis V.

Interferons are released from infected viruses or other antigens. There are many different interferons that manifest multiple effects that include inhibition of the broadcast and transcription of viral RNA, cessation of viral replication without disrupting the function of the host cell. Interferons are sometimes given in the form associated with polyethylene glycol (pegylated interferons), which makes it possible to achieve a prolonged effect.

Interferonotherapy is used to treat hepatitis B and C and Papillomavirus man. Interferons are shown for the treatment of patients with chronic hepatitis B, with in combination with a violation of the liver function determined by the viral load and the presence of an appropriate histological picture. Interferon-2B is used to treat hepatitis B at a dose of 5 million units subcutaneously 1 time per day or 10 million units are 3 times a week for 16 weeks. Treatment enhances the pulse of the Hepatitis B virus and nveag from plasma, improves the function of the liver and histological picture.

Hepatitis C is treated with ribavirin in combination with pegylated interferons-2V at a dose of 1.5 μg / kg subcutaneously once a week or a pegylated interferon-2a 180 μg subcutaneously 1 time per week. The treatment reduces the level of viral RNA, improve the function of the liver and histological picture. Interferon-p3 intramuscularly or directly in the affected area is used in the treatment of genital and skin peptilicular. The optimal schemes and the duration of the effect are unknown. The effectiveness of the use of recombinant forms of endogenous interferon alpha with high-cooled leukemia, sarcoma capos, human papilloma virus and respiratory viruses are studied.

Side effects include fever, octvines, Malgia, weakness, begin 7-12 hours after the first injection and last to 12 hours. Also depression, hepatitis and when using high doses, bone marrow oppression.

Vaccines and immunoglobulins.

Vaccines stimulate natural immunity. Viral vaccines against influenza, measles, steaming, poliomyelitis, rabies, rubella, hepatitis B and a, having listened and yellow fever are used. Vaccines against adenoviruses and wind sieves are available, but they are used only in high-risk groups (for example, in recruits).

Immunoglobulins are used for passive immunization in a limited range, for example, for post-exposure prevention (hepatitis, rabies). Others can be useful in treating diseases.

Respiratory viruses

Viral infections more often affect the upper and lower respiratory tract. Respiratory infections can be classified in accordance with the viruses that caused them (for example, influenza), but usually use clinical syndromic classification (for example, colds, bronchiolitis, croup). Although individual pathogens are inherent specific clinical symptoms (for example, rinovirus and cold, respiratory syncytial virus and bronchiolitis), each virus can lead to almost any symptom.

The severity of viral infection varies widely, and heavier it flows in children and the elderly. Mortality is determined by direct reasons (depends on the nature of viral infection), as well as indirect (as a result of exacerbations of concomitant cardiovascular pathology, bacterial superinfection of the lungs, apparent sinuses of the nose, middle ear).

Laboratory study of pathogens (PCR, culture research, serological tests) takes too much time to be useful for a particular patient, but it is necessary to analyze the epidemic situation. A faster laboratory examination is possible against influenza viruses and respiratory syncycial virus, the value of these methods in routine practice remains unclear. Diagnostics is based on clinical and epidemiological data.

Treatment

Treatment of viral respiratory infections is usually symptomatic. Antibacterial agents are ineffective in relation to viruses, and prevention against secondary bacterial infection is not recommended: antibiotics are prescribed only with an already connected bacterial infection. In patients with chronic pulmonary pathology, antibiotics are appointed with smaller constraints. Children should not apply aspirin due to the high risk of developing the syndrome Rei. In some patients with viral diseases of the upper respiratory tract, the cough is preserved for many weeks after recovery. Symptomas can give in to the effects of broutine and glucocorticoids.

In some cases, antiviral drugs are important. Amantadine, Remantadine, Osillavir and Zavirvir are effective for influenza. Ribavirin, an analogue of Guanozin, inhibits the replication of RNA and DNA of many viruses and can be administered to immunospless patients with rhinosinessitial lesions of the lower respiratory tract.

Cold

This is an acute respiratory infection of the respiratory tract, self-disseminating and usually flowing, with inflammation of the upper heights of the respiratory tract, including rinore, cough, throat. Diagnosis is clinical. Prevention helps careful washing hands. Treatment is symptomatic.

In most cases (30-50%), the pathogen is any of the more than 100 serotypes of the rinovirus group. The cold is also caused by viruses from the group of coronaryoviruses, influenza, paragrippa, respiratory syncitial, especially in patients carrying reinfection.

Cascitioners of colds have communication over time of the year, more often it is spring and autumn, less often - winter. Rinoviruses most often apply to direct contact with an infected person, but can be transmitted and airborne droplets.

For the development of infection, the presence in serum and secrets of neutralizing specific antibodies, reflecting former contact with this pathogen and providing relative immunity. The duration of the cold exposure, the state of health and nutrition, the pathology of the upper respiratory tract (for example, increased almonds and adenoids) does not affect sensibility.

Symptoms and diagnostics

The disease begins suddenly after a short hatching period (24-72 hours) with unpleasant feelings in the nose and throat, after what they appear, runny nose and malaise. Temperature usually remains normal, especially when the cause is Reno- and Coronovirus. In the first days of discharge from the nose, watery and abundant, then become more dense and purulent; The mucous-purulent nature of these discharge is due to the presence of leukocytes (mainly granulocytes) and not necessarily secondary bacterial infection. Swashing with scarce mooring often continues for 2 weeks. If there is no complications, the symptoms of the cold subsided in 4-10 days. With chronic diseases of the respiratory tract (asthma and bronchitis), after a cold, there are usual exacerbations. Purulent sputum and symptoms from the lower respiratory tract are not very characteristic of rinoviral infection. Purulent sinusitis and inflammation of the middle ear are usually bacterial complications, but sometimes they are associated with primary viral infection of the mucous membranes.

Diagnostics are usually clinical, without diagnostic tests. Allergic rhinitis is most important for differential diagnostics.

Treatment and prevention

Specific treatment does not exist. Antipyrtic and analgesics are usually used, which reduce the fever and reduce the throat. When nasal is running, decongestants are used. Local nasal decogestants are most effective, but their use of more than 3-5 days can lead to an increase in nasal discharge. For the treatment of rinoresis, angihystamine preparations of the first generation can be used (for example, chlorophenyramide) or IPratropium Bromide (intranasal 0.03% solution 2-3 times a day). These drugs, however, should be excluded in the elderly and individuals with a benign hyperplasia of prostate and persons with glaucoma. Antihistamines of the first generation cause drowsiness, however, the second generation preparations (without a sedative effect) are not effective for the treatment of colds.

Zinc, Echinacea, Vitamin C is universally used to treat colds, but their effects are not proven.

There is no vaccine. Polyvalent Bacterial Vaccines, Citrus, Vitamins, Ultraviolet, Glycolic Aerosols and others folk remedies Do not prevent colds. Hand washing and using surface disinfectants reduce the prevalence of infection.

Antibiotics are prescribed only when the secondary bacterial infection is connected, the exception is patients with chronic lung diseases.

Paragripp.

Respiratory diseases caused by several close-friendly viruses vary from colds to flu-like symptoms or pneumonia, and in heavy form at high temperatures appearing most often as influenza. Clinical diagnosis. Treatment is symptomatic.

Paragripping viruses are RNA-containing paralimixes of four serologically different types, denoted by 1,2,3 and 4. These four serotype cause diseases of various severity, but have general antigens. Serotype 4 cross-reacts with antigenic determinants of epidemic vapotitis virus and can sometimes cause a respiratory disease.

Limited outbreaks of paragrippa are in schools, nursery, kindergartens, hospitals and other institutions. Serotypes 1 and 2 cause autumn outbreaks of the disease. The disease associated with serotype 3, endemic and highly contagious for children under 1 year. Perhaps re-infection, the severity of subsequent infections is reduced and their distribution is limited. Thus, immunocompetent persons are asymptomatic infection.

Most often, children are affected by the upper respiratory tract with or without a small fever.

With damage to the type 1 paragripping virus, croup (acute laryngo-tracheobronchitis) is developing, mainly in children aged 6-36 months. The croup begins with the symptoms of the cold, then the fever and the barking cough, the hoarseness of the voice, Stridor, are joined. Respiratory failure is rare, but may have a fatal outcome.

The type 3 paragripping virus may be the cause of the development of pneumonia and bronchipolitis in young children. The disease requires differential diagnosis with respiratory syncytial infection, but often weaker.

Specific laboratory diagnostics is not required. Treatment is symptomatic.

Respiratory and sycitial and metapneumovirus infection

Respiratory and synticial virus (RSV) and human metapneummirus (FMV) cause a seasonal defeat of the lower departments of the respiratory tract, especially in young children. The severity of the disease varies from asymptomatic flow to severe, and clinical manifestations include bronchiolite and pneumonia. The diagnosis is usually clinical, although laboratory testing capabilities are available. Treatment is symptomatic.

RSV - RNA virus, classified as Pneummovirus, has subgroups A and V. Human Metapnemovirus (FMW), similar, but a separate virus, is open recently. RSV is common everywhere, almost all children are infected by 4 years of life. Flashing diseases usually occur in winter or early spring. Immunity at the inconsistent unstable, so the contagiousness reaches 40%. Nevertheless, the presence of antibodies against the RSV reduces the severity of the disease. The epidemiological features of the distribution of FMW are similar to the RSV, but the severity of flashes is significantly lower. RSV - the most frequent cause diseases of the lower departments of the respiratory tract in young children.

Symptoms and diagnostics

The most characteristic symptoms are bronchiolite and pneumonia. In typical cases, the disease begins with fever, respiratory symptoms that progress: after a few days, shortness of breath, cough, wheezing. In children under 6 months, the first symptom can become apnea. In healthy adults and older children, the disease usually proceeds asymptomatic or in the form of a bestless cold. Heavy illness is developing in elderly, immunosprometed persons suffering from concomitant pulmonary and cardiac pathology.

RSV (possibly, and the FMV) should be suspected of young children with symptoms of bronchiolite and pneumonia in the season, characteristic of RSV. Since antivirus treatment is generally not recommended, the need for laboratory diagnostics not. The latter is useful for in-hospital control, which allows you to allocate groups of children affected by one virus. For children there are highly sensitive tests for determining the RSV antigens; For adults, they are insensitive.

Treatment and prevention

The treatment is symptomatic, involves inhalation of oxygen and hydration therapy as needed. Glucocorticoids and bronchodulators are usually ineffective. Antibiotics are reserved for patients with continued fever and confirmed by pneumonia radiographic examination. Palivizumab for treatment is ineffective. Riba-Wormin, which has antiviral activity, against RSV is ineffective or ineffective, has toxicity and is not recommended for long-term admission, with the exception of immunospro-industrial faces.

Passive prevention by monoclonal antibodies to RSV (palivizumab) reduces the frequency of hospitalizations in high-risk adolescent groups. Economically, vaccination is justified for young children who may need hospitalization (that is, aged less than 2 years) with congenital heart defects or chronic lung diseases that required drug treatment in the last 6 months, premature children (less than 29 weeks) who met the RSV season At the age of less than 1 year, or born in the period 29-32 gestation weeks and met the RSV season aged less than 6 months). The dose is 15 mg / kg intramuscularly. The first dose is appointed only before the occurrence of the exacerbation season. Subsequent doses are given at intervals of 1 month during the entire epidemiological season, usually 5 doses.

Heavy acute respiratory syndrome

Predictors of fatal outcomes are age over 60 years, severe concomitant pathology, raising the level of LDH and an increase in the absolute number of neutrophils. Treatment of torso is symptomatic, if necessary, mechanical ventilation of the lungs. Omeltonvir, Ribavirin and glucocorticoids can be used, but there are no data on their effectiveness.

Patients with suspicion of torso must be hospitalized in boxing with negative intra-oxide pressure. All activities should be performed on the prevention of infection with respiratory and contact path. The staff should wear N-95 masks, safety glasses, gloves, bathrobes.

People who have in contact with patients with SARS (for example, family members, flight attendants, medical personnel) must be warned about the symptoms of the disease. In the absence of symptoms, they can work, attend school, etc. If fever appears or respiratory symptoms, they must limit their activity and are under medical supervision. If the symptoms do not progress towards the torso within 72 hours, they can be considered tolerant.

T4 bacteriophage refers to the major phages of the T-even series. The DNA phage T4 linear, two-stranded, has a molecular weight of 120 * 10 6, the length of 165 thousand pairs of bases., Which is sufficient for coding about 200 genes. The position on the genetic map of almost 100 phage genes was determined (Fig. 1). For phage DNA molecules, end redundancy is characterized (the length of these sites is a few percent of the entire length of DNA, i.e. several thousand base pairs). The phage DNA molecules are the same in size and genetic composition, but heterogeneous on the nucleotide sequence (as a result of cyclic permutations of genes).

T4 is a very large phage, which has a fairly complete and independent replicative apparatus. For one minute after the adsorption of the phage T4, the synthesis of the host molecules is almost completely terminated, the transcription of some phage genes begins and after 4 minutes there is already replication of phage DNA. FAGOM infection T4- Perfect model for studying the control of replication and expression of genes.

The Phage T4 DNA replication begins at a point located between the genes 42 and 43 and goes in two directions. Later there are many replication points, resulting in up to 60 replicative forges.

One of the advantages of using the T4 phage as a model system to study the DNA replication is that all the proteins needed for the elongation of the chain are encoded by phage. Identified 11 proteins involved in the formation and movement of a replicative fork, but only 5 of them are necessary for creating a cow system. These are gene products 43 (T4 DNA polymerase), 32 (protein connecting single-chain DNA), 44, 62, 45 (auxiliary proteins). The interaction of these proteins determines the accuracy of replication.

The composition of the DNA phage t4 (and other T-even phages) instead of ordinary cytosine. An unusual base is oxymethyl excitosis (OMC). Most OMC residues glucosylated. DNA with such modified bases does not cut almost all known restrictions. Restriction enzymes E.Coli. Learn the nobosylated OMC residues in certain sequences, and destroy such DNA. T-even phages are not only protected from master restrictions, but also encode nucleases, degrading unmodified DNA hosts that do not operate on phage DNA.

Glycosylation of OMC residues in phage T4 DNA is genetically determined, it occurs by transferring glycosyl DNA residues within a few minutes after polymerization using specific enzymes - glycosyltransferase. This method of struggle could occur only in such a major phage as T4.

The virus has done a long time ago
About different forms of the virus of the carrier death is described in the ancient manuscript Voyan.

By 2020, the virus is programmed as an epidemic of plague from which there are no drugs.

But I suppose the medicine is and it is accessible to everyone,
Medicine for free and very effectively.

Bacteriophage T4 (English Escherichia Virus T4, previously Enterobacteria Phage T4) is one of the most studied viruses, bacteriophage, affecting enterobacteria, including Escherichia coli. It has a genomic DNA of about 169-170 thousand nucleotide pairs, packed in a ikosahedral head.

The virion also has a trunk, base of trunk and stem processes - six long and six short.

T4 bacteriophages uses a ring-type DNA polymerase; Its sliding cuff is a trimer similar to PCNA, but it does not have homology with NE with PCNA, nor with polymerase β.

T4 is a relatively large phage, has a diameter of about 90 nm and a length of about 200 nm. FAG T4 uses only a littic development cycle, but not a leased.

The English bacteriologist Frederick Tores in Article 1915 described the infectious disease of staphylococci, the infectious agent passed through the filters, and it could be transferred from one colony to another.

With Fagom T4 or similar bacteriophages, the laureates of the Nobel Prize Max Delbryuk, Salvador Luria, Alfred Hershei, James Watson and Francis Creek, as well as other famous scientists - Michael Rossmann, Vadim Meranzhinov, Fumio Arisaka, Seymour Benzer, Bruce Alberts.

Regardless of Frederick Tore, the French-Canadian Microbiologist Felix D'Elell on September 3, 1917 reported the opening of bacteriophages. Along with this, it is known that the Russian microbiologist Nikolai Fyodorovich Gamaley in 1897 first observed the phenomenon of lysis of bacteria (a sybiced stick) under the influence of a translated agent.

In 2016, like other bacteriophages, was renamed Escherichia Virus T4.

Felix D'Elell also put forward the assumption that bacteriophages have a corpuscular nature. However, only after the invention of the electron microscope, it was possible to see and explore the phage ultrastructure. For a long time, the ideas about the morphology and the main features of the phages were based on the results of the study of the phages T-group - T1, T2, ..., T7, which multiply on E. coli strain B. However, new data appeared every year concerning the morphology and structure of various phages, What caused the need for their morphological classification.

Bacteriophages are the most numerous, widespread in the biosphere and, presumably the most evolutionarily ancient group of viruses. The approximate size of the phage population is more than 1030 phage particles.

Bacteriophage structure

Bacteriophage Structure.png.

1 - Head, 2 - Tail, 3 - nucleic acid, 4 - capsid, 5 - "Collar", 6 - Protein Case Tail, 7 - Tail Fibril, 8 - Spikes, 9 - Basal Plate

Bacteriophages differ in the chemical structure, the type of nucleic acid, morphology and the nature of interaction with bacteria. In size, bacterial viruses are hundreds and thousands of times less microbial cells.

A typical phage particle (Virion) consists of head and tail. The tail length is usually 2-4 times larger than the diameter of the head.

The head contains genetic material - single-stranded or double-chain RNA or DNA with an enzyme transcriptase in an inactive state, surrounded by a protein or lipoprotein shell - capsid that preserves the gene from the outside cell.

In natural conditions, phages are found in those places where bacteria sensitive to them. The richer one or another substrate (soil, the allocation of man and animals, water, etc.) by microorganisms, the more in it there are corresponding phages. So, phages, lyseing cells of all types of soil microorganisms are in soils. Especially rich in the phages of black soil and soil, in which organic fertilizers were introduced.

Nucleic acid and capsid together make up nucleocapsid. Bacteriophages may have an ikosahedral capsid, assembled from a variety of copies of one or two specific proteins. Typically, the angles consist of protein pentamers, and the support of each side of the hexamers of the same or similar protein. Moreover, phages in shape can be spherical, lymonic or pleomorphic.

The tail, or the process, is a protein tube - the continuation of the protein shell of the head, at the base of the tail there is a atfez, which regenerates the energy for the injection of genetic material. There are also bacteriophages with a short process, not having a process and filamentons.

Head of a rounded, hexagonal or roller shape with a diameter of 45-140 nm. The process is 10-40 thick and 100-200 nm long. Some of the bacteriophages of the rounded, other filadines, the size of 8 × 800 nm. The length of the nucleic acid thread is many times the size of the head, in which it is in the twisted state, and reaches 60-70 microns. The process has a view of a hollow tube, surrounded by a case containing contractile proteins like muscle. A number of viruses have a case capable, exposing part of the rod. At the end of the process, many bacteriophages have a basal plate, which departs thin long threads that contribute to the attachment of the phage to the bacteria. The total amount of protein in the phage particle - 50-60%, nucleic acids - 40-50%.

In some phages, the genome contains several thousand grounds, while FAG G, the largest of sequenced phages, contains 480,000 base pairs - twice as many mean values \u200b\u200bfor bacteria, although there is still an insufficient number of genes for such an essential bacterial organoid as ribosomes.

Bacteriophages perform a role in the control of microbial populations, in the autolysis of aging cells, in the transfer of bacterial genes, speaking as vector "systems".

Indeed, bacteriophages are one of the main moving genetic elements. By transduction, they bring new genes to the bacterial genome. It was estimated that 1024 bacteria could be infected in 1 second. This means that the constant transfer of genetic material is distributed between bacteria living under similar conditions.

The high level of specialization, long-term existence, the ability to quickly reproduce in the relevant host contributes to their preservation in a dynamic balance among the wide variety of types of bacteria in any natural ecosystem.

When the appropriate host is absent, many phages can preserve infection ability for decades if they are not destroyed by extreme substances or the conditions of the external environment.