Types of viral infections. Types of viral infections What characterizes satellite viruses

Independently. They infect cells that are immune to natural death due to old age (for example, amoebas, bacteria). When a cell infected with a satellite virus is infected by the original virus, the satellite virus destroys the production of virions of that virus and begins to multiply. Satellite viruses, in essence, are hyperparasites.

Thus, the virophage “Suputnik” ( Сputnik virophage) is a subviral agent that reproduces in amoebae infected with mimivirus ( Acanthamoeba polyphaga mimivirus).

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A lesson that characterizes satellite viruses

When the virus interacts with the cell, it can be created as mature infectious parts, called defective viruses or HIV with a defective genome.

A defective genome is a viral genome in which one or more genes have lost a function necessary for autonomous replication of the virus, in connection with which replication requires the assistance of another viral genome or gene. We observed 5 classes of defective viral genomes that retained their biological activity:

1. Defective genomes that lie in the side virus.

2. Defective genomes integrated into the human chromosome.

3. Satellite viruses.

4. Pseudovirions.

5. Mentally defective genomes.

Defective genomes that lie in the midget virus. These include the so-called defective interfering viruses – D-particles. They are subgenomic deletion mutants that have lost the entire genome of the father's virus. Deletions can reach 90%, although deletions affecting less than 1% of the genome are detected. To renew the functions of the DI-particle, it is necessary to immediately become infected with the native virus. In this case, the DI-particles suppress (interfer) the replication of the parasitic virus, resulting in the production of its powerful genes.

Di-particles are created during replication of any virus, grow in size compared to the normal virion and may cause a different level of interference. For example, DI particles interfere weakly with poliovirus, and DI particles interfere strongly with vesicular stomatitis virus.

Defective genomes integrated into the chromosome of the host. The fact of integration of the genome of low viruses into the genome of the host kingdom does not raise any doubts. Both defective and defective genomes can be integrated, especially in bacterial cells. As a rule, these are defective genes, which are why they are “moving”. In the singing minds the stench can be overwhelming induced(activation, start of replication) their expression can influence the survival and evolution of the ruler’s culture. When inducing such genomes of bacterial viruses with the help of mitomycin and ultraviolet radiation, it is possible to prevent the creation of virus fragments: empty heads, tail appendages, and outer heads without appendages. Induced phage particles can cause the death of virus-sensitive strains of bacteria. Just like normal integrated genomes, integrated defective genomes can inactivate the genes of the host cell or express them, give new genetic powers, introduce, absorb or interfere with them. x expression, remove or move regulatory elements, as well as accept recombination changes in the DNA of the host’s cell.

In recent years, it has been established that a significant portion of oncogenic RNA fluff viruses are defective viruses that carry cell oncogenes and lie within the host virus. For example, the LTR sequences of defective retroviruses, when they are infected nearby oncogenes, activate them.

1. STNV – a satellite of the tuberculosis necrosis virus, a companion – the tuberculosis necrosis virus.

2. Satellite – coliphage p4, pomichnik – coliphage p2.

3. AAV – adeno-associated viruses, pomichnik – adenoviruses.

4. Delta – virus, parasite – hepatitis B virus.

Pseudovirioni- this is HF, which replaces the genomic nucleic acid of the virus, nucleic acid the ruler's cloister. In prokaryotes, the creation of such pseudoviruses has great genetic significance and a mechanism of movement genetic material the gentlemen's clients from one client to another. In eukaryotes, the genetic significance of pseudovirions has not been established, but their study is indicated. For example, when infected with polyoma virus, a large proportion of the offspring that are created are pseudovirions.

Mentally defective genomes- these are mutant genomes, defective even for the brightest minds: ts-mutants (temperature-sensitive); hr-mutanti (beyond the spectrum of hospodars) and others.

The creation of new virions and their release will end productively.

Integrative – to lead to the establishment of a less stable virus-cell association, for example: a prophage, a provirus in the genome of the host cell.

Abortive – accompanied by the elimination (depletion) of the virus, and if infected with the virus, the cells in your body can either die or be lost alive.

Satellite viruses

Hepatitis D virus, born 1977 as a companion (satellite) to the hepatitis B virus (helper). Not suitable for independent reproduction. There are 2 proteins: the outer one – HBsAg and the inner one – HDAg.

Defective satellite viruses of tuberculosis necrosis and circumferential polymorphism have defective genomes. Their replication and maturation are only possible in the presence of the parent virus.

When the satellite virus multiplies, it creates a hidden replicative system with the satellite virus.

Viroi vidkriv 1972 r. T. Diner. The stinks call out 11 diseases of the plants that were previously considered viral:

1) spindle-shaped potato bulbs,

2 – 4) dwarfism of chrysanthemums, hops and burdock,

5) brightness of the eye,

6) citrus exocortis,

7) chlorotic speck of cherries,

8) avocado juices,

9) bushiness of tomato tops,

10) thorn plant maho tomatoes

11) Kadanga-Kadanga coconut palm tree.

Viruses are transmissible subviral agents with powers unique to viruses.

Viruses are covalently closed circular RNA molecules that contain protein shells.

Features of the RNA of viruses

Minimum dimensions: 300 – 400 nucleotides.

The existence of antigenic powers.

The presence of a tertiary structure.

Inability to accept amino acids.

They are created with the help of enzymes of the host cells in the core of infected cells or autocatalytically.

Its synthesis is inhibited by actinomycin.

Viruses have impaired replication and maturation functions. The role of regulatory elements may be lost. Apparently, viruses cause the cells they infect to make new copies, stimulating the transcription of certain genes.

It is assumed that the mechanism of action in infected cells is similar to proions!

Prions (from the English “protein infection”) are infectious non-nucleic structures that are composed of a low molecular weight protein of 27 - 30 kDa.

More neuroinfections - precipitating transmissive spongy (lip) encephalopathy

kuru – “to laugh at the death” of people,

Kreintzfeld-Jacob disease,

Gerstmann-Sträussler-Shaker syndrome,

fatal family insomnia,

creaking (twirling) sheep and kiz,

Infectious encephalopathy of domestic minks,

chronic deforestation of domesticated deer and elk,

transmissive spongiform encephalopathy of cows - “break of cows”

The underground authorities of the field encephalopathies:

trivial (several fates) incubation period,

progression without remissions,

irreversible degeneration of neurons,

lethal end.

Most encephalopathies can be caused by canonical viruses such as sheep.

The power of the demons, typical for the most common viruses

Ultramicroscopic dimensions.

Non-production until reproduction on living media.

A number of specific rulers.

Trival persistence in the body.

M.: Svit, 1989. – 492 p.
ISBN 5-03-000283-9
entice(straight up) : virusologiyat11989.djvu Front 1 .. 56 > .. >> Advance
satellite viruses
Satellite viruses are an extreme form of parasitism. The stench is carried to viruses that parasitize on genetic products created by other, often unrelated viruses. Like the D-particles, they are defective and cause the whole world to interfere with their viruses; however, the change in di-particles of the culprit of satellite viruses is not connected (accepted indirectly) with the deletion of genes in viruses, such as those lying in their replication. Quite often the RNA or DNA genome of the satellite virus has no homology with the genome of the satellite virus. One of the simplest applications is the satellite virus necrosis virus (STNV). The virus remains in the process of its replication due to the one-hour infection of the cells of the titanium with its infectious parasitic virus, the tuberculosis necrosis virus. The icosahedral particles of STNV are significantly smaller than those of the virus necrosis virus, and their defective RNA genome is smaller than the genome of the virus necrosis virus. The single-lane RNA genome of STNV encodes its own envelope protein and, after replication to its sister virus, is covered with this envelope.
A significantly folded satellite virus is
coliphage p4. This dead phage itself infects and lysogenizes Escherichia coli, but it is not possible to replicate and create mature phage particles without its defective virus-related coli-phage p2 (a larger and also dead phage). . A number of p4 phage gene products activate late transcription of the genes of their p2 phage. Some of the products of late genes p2 are capsid proteins, and others activate the synthesis of capsid proteins by late genes of the satellite virus p4, which initiates the synthesis of p2. This mutual trans-action of gene products between the host virus and the satellite virus is called trans-activation.
With a butt Human satellite viruses serve as adeno-associated virus (AAV). These small icosahedral viruses contain one plus or minus DNA that encodes three capsid proteins for encapsidation of their small defective genomes. AAV can only replicate in cell nuclei that are infected with adenoviruses (herpesviruses can also frequently stimulate AAV replication). AAV replication interferes with the replication of their adenovirus markers and the transformation of cells by adenoviruses. A number of serological types of AAV have been seen in people infected with adenoviruses, but the role they play in weakening (or strengthening) adenovirus disease is unknown.
It is noteworthy that it has been infected with a defective satellite genome, also called a delta agent, associated with several important forms of liver disease that are caused by the hepatitis B virus. mass: ~5.5-103, similar in size to the STNV genome. At this time, very little is known about the nature of this RNA to be able to explain this situation. It is possible that this is due to the fact that the hepatitis B virus relies on reverse transcription of RNA for the synthesis of viral single-stranded DNA. Delta-agent RNA was detected in the human population in a subpopulation of hepatitis B surface antigen particles with a diameter of 35-37 nm, which carry the delta antigen. The delta-agent can be transmitted to chimpanzees, but only in combination with the hepatitis B virus. To determine its role in the development of severe liver disease or any other illness, additional investigations are required.
There are a lot of satellite viruses and satellite-like viruses, especially among viruses with separated genomes. Recognized activities from them, such as CARNA5 (RNA associated with the orange mosaic virus), may play an important role in nature, because
It is very important to overcome the illness, which means weakening or severe symptoms of illness in the presence of the lord of the plant. Without sufficient information about the sequence of nucleic acids, it is often impossible to isolate satellite viruses from DI particles. For example, chronic paralysis virus (CPVA) and a satellite-like virus, which is replicated only in patients infected with chronic paralysis virus (CPV), and not serologically associated h CPV. However, the sequence of this RNA has some homology with the sequence of CPV RNA and may have evolved from one of the segments of this RNA. You can look at it either as a satellite virus or as a D-particle that has significantly evolved. At the same time, the satellite of the turnip twisting virus, which causes illness in plants, has only a small number of homologous oligonucleotides with its host virus. Obviously, it has evolved either from a segment of the genome of the host virus or from a segment of other unconjugated RNA.
Pseudovirioni
Pseudoviruses are particles that replace the nucleic acid of the host cell, which completely replaces the nucleic acid of the viral genome. They have a biological role in infections caused by viruses of creatures, unawares, and for a number of viruses of creatures, such as the polyoma virus, pseudoviruses form a significant part of germination in cells of all types. Phages that carry out generalized transduction cause revenge only on the DNA sequences of the host cell, and these phage “pseudovirions” may be of great genetic significance in prokaryotes. Regardless of the fact that there may be genetic significance in the nature of pseudovirions of animal viruses, they can be traced to a potential mechanism for the effective introduction of certain foreign genes into the cells of animals.