The 5 types of viruses, and how they work

We summarize the functioning of these microscopic bodies that cause infections.

When talking about living beings, no discussion is generated by indicating that an animal or a plant is one. The same is true for fungi, algae and bacteria. But when it comes to viruses, things change.. These infectious agents break the rules.

First, they are not cells, but simple protein structures that contain genetic material. Second, their only way to reproduce is by infecting cells, to use their tools for this purpose. And third, they do not need to obtain any kind of energy, since they do not require maintenance.

Apart from the discussion of whether they are considered living beings or not, there is variety both in their content and in their structures, which has made it possible to identify different types of viruses. The importance of knowing them better has to do with their role in causing diseases in living beings, some of which are more serious than others. A better knowledge helps to the prevention and treatments of these.

Basic structure of a virus

Viruses stand out above anything else for being of very simple composition. It is a protein structure, with greater or lesser complexity depending on the type, which has the following objectives protect the genetic material it carriesand at the same time acts as a vehicle for it.

Capsid

The main structure that all viruses have is the capsid. It is formed by a set of protein units called capsomers.When it contains the genetic content, it changes its name to nucleocapsid. The shape adopted by this piece is one of the criteria for identifying types of viruses.

The nucleocapsid can present an icosahedral symmetry, which is observed as a spherical shape; a helical symmetry, which is rod-shaped or tubular.The nucleocapsid can have icosahedral symmetry, which is observed as a spherical shape; helical symmetry, which is rod-shaped or tubular; and complex symmetry, apart from the nucleocapsid, it has a protein structure attached to it that is known as a tail, which acts as a support to facilitate the insertion of the contents into a host.

Envelope

Independently of this, some viruses may have a second layer, called the envelope, which is made up of lipids. Its presence or absence is another criterion used to classify them.

Types of viruses according to their genetic material

Unlike cells, the genetic content of these infectious agents is most varied in classes and configurations, so it is a good point to use in taxonomy. Roughly speaking, there are two major types of virusesViruses: those that contain DNA as genetic material and those that store their information in the form of RNA.

DNA viruses

Types of DNA viruses possess a small strand of nucleic acids, which can be either single-stranded or double-stranded, i.e. in one which can be either single-stranded or double-stranded, i.e. in one or two strands. In addition, it can be in circular or linear form, it all depends on which virus we are talking about. These are the most common viruses to be found. For example, the herpes virus (Herpesviridae) has genetic content that is in the form of linear double-stranded DNA.

RNA viruses

As you can already imagine, the only difference between RNA viruses and the others is in the nucleic acids. It is the same: it can consist of one or two strands, and be in linear or circular form. A well-known example is the family of retroviruses (Retroviridae). (Retroviridae), among the diseases they can cause is AIDS. In this case, it presents its genetic material in the form of linear single-stranded RNA.

Depending on what they infect

Not all types of viruses have an affinity for the same organisms or cells. In other words, some viruses only affect animals and not plants.. Thanks to this, it can be used as a criterion for classification. In this case it focuses on what is their host, there being three groups:

• Animal viruses.
• Plant viruses.
• Bacteriophage viruses (they attack bacteria).

The case of coronaviruses

Recently, the term "coronavirus" has become world famous as a result of the global pandemic caused by one of the species of viruses caused by one of the virus species belonging to this category. This is the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), which causes the disease called COVID-19, a pneumonia with a relatively high mortality rate in humans. This pathogen variant was discovered in the Chinese city of Wuhan, but since this point of origin, it has mutated several times.

But beyond this case, coronaviruses are types of viruses that have been known for a long time and that in the taxonomy used to classify these Biological entities are in the family of the Coronaviridaeand are therefore considered to constitute a subfamily.

One of the characteristics of these species is that they are the RNA viruses with the longest genome, and because of the protrusions of the genomeThe most common characteristic of these species is that they are the RNA viruses with the longest genome, and because of their rounded surface protrusions, which, when viewed under the microscope, make them appear to have a crown with spikes. On the other hand, most coronavirus species do not pose a significant danger to most people.

How do they work?

I could not end this article without explaining how viruses work in a generic way. The viron (mature form of the virus), locates a host cell, managing to introduce its genetic content inside. This material is inserted into the DNA of the nucleus, so that the cell can transcribe its information and translate it into proteins. transcribe its information and translate it into the proteins that make up the capsid and capsid proteins that make up the capsid and so on. It is also possible to replicate the genes of the virus, thus introducing it into the new capsids and forming new virons that emerge from the infected cell.

This is a generic way of talking about the life cycle of viruses; there are a multitude of variables. Examples cited, such as retroviruses, first have to transcribe their RNA content into DNA and manufacture the complementary strand before they can insert themselves, since cells contain their genetic material in the form of double-stranded DNA.

The cause of viruses generating diseases is due to this insertion into the cell's DNA, which can translocate genes, in addition to permitirles tomar control de la célula para su proliferación, haciendo que no funcione de forma correcta.

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