DNA viruses

The world is full of viruses. Some can be combated successfully, while others cause serious diseases. The following text should explain why this is so. DNA viruses are viruses whose genome consists of DNA (genetic material).

What are DNA viruses?

A virus in general is a carrier of infection that consists of a strand of genetic material. This can consist of DNA (deoxyribonucleic acid) or RNA (ribonucleic acid). The strands are wrapped in a protein shell. A DNA virus is a virus whose genetic material consists of deoxyribonucleic acid.

The genetic material is called the genome. The genome can be double-stranded or single-stranded. The strands themselves consist of one piece (non-segmented) or can be divided into different pieces (segmented). A DNA genome has the ability to appear in a ring (circular) or in an open strand (linear). In contrast to RNA viruses, DNA viruses are less variable.

As a result, they are often stable to environmental influences. The reason for this is their higher chemical stability and their lower mutation rate. Their enzymes, which are used to replicate DNA, the DNA polymerases, have their own proofreading function. This means that incorrectly incorporated DNA is recognized and removed. This means that mutations are less common. The viruses are not able to cope with independent metabolic processes. For this you need a host cell into which your own genetic material is introduced.

Research counts many different viruses and divides them into 20 virus families. The following is a list of the six most important types of viruses:

• Herpes viruses
• Human papillomavirus
• Parvoviruses (Parvoviridae)
• Human adenoviruses
• Smallpox viruses
• Hepadnaviruses

Meaning & function

If the body is infected by viruses, the entire body is on alert. Due to the ability of DNA viruses not to be able to build up their own metabolism, they are dependent on infecting a cell.

They use the body's own cells as a host. They bring their own genetic material into these occupied cells. From this point onwards, the infected cell then uses the foreign genetic material to create new viruses. When the viruses are released, the cells die. The viruses cause the cells to self-destruct. The immune system of the human body tries to prevent the cells from becoming infected. Scavenger cells are sent out to destroy the DNA viruses and diseased cells.

Typical symptoms of illness such as fever, weakness and loss of appetite arise during the defense reaction. If the body survives an attack by the viruses, there is retrospectively immunity to these viruses. The immune defense has created memory cells that can recognize the enemy if they attack again. As a result, people only get chickenpox, mumps or measles once in their life.

In the context of vaccinations, weakened viruses are used for immunization. These cause the body to develop defenses. If there is a possible infection, the immune system can fight the virus directly. In the western world it has been possible to achieve the approximate eradication of chickenpox with the help of vaccination. However, there are also infections that cannot be treated with vaccinations. This includes the HI virus, which attacks the body's own immune cells and makes a previous vaccination unnecessary.

Viruses are very dangerous to humans and animals. They are extremely adaptable and changeable. The genetic make-up of DNA viruses is constantly changing through mutation. They can change their surface, based on which they are recognized by the body's own defense system. They outsmart the antibodies that are formed because they can no longer dock onto the surface of the virus. The antibodies can no longer recognize and destroy the viruses due to the changed surface. For this reason, new vaccines against influenza viruses are used for the vaccinations every year.

Illnesses & ailments

DNA viruses also have the ability to skip from one species to the next. They can pass from animals to humans in order to reproduce on their new host.

This is extremely dangerous as the existing defenses remain largely ineffective. The host is thus highly infectious and it can spread quickly. This happened with the swine flu or the bird flu. For the animal virus to function in humans at all, more than just one mutation is necessary. Two different viruses mix together to form a new virus. In order to limit the risk of pandemics, many viral diseases are therefore notifiable.

DNA viruses pose a further danger as they can be in the body for years without causing symptoms. The infection only leads to cell damage and a noticeable disease when other triggers are added.

Herpes viruses are one of the most common DNA viruses. The herpes simplex virus in particular is widespread. An infection can be recognized by blisters on the face, lips, oral mucosa or eyes.