Reproduction mechanism of viruses

In addition, the virus is able to multiply (replicate) by introducing its DNA or RNA into the host cell. The first step is always for the virus to attach itself to the host cell. The genetic material is then introduced into the cell.

There the envelope(s) are then removed (uncoating), after which the nucleic acid can enter the cell nucleus. There it practically takes over the control and first of all ensures that the genetic material is multiplied and proteins are produced. From these individual components, new viral particles can finally form again.

There are two different ways in which the virus can complete its multiplication. 1. lytic cycle: here the cell membrane is completely dissolved, i.e. the cell is destroyed and the new viruses are released. 2. lysogenic cycle: the cell does not die but the viruses are only expelled from it (budding) by taking a part of the cell membrane of the host cell to form an envelope. How many viruses emerge from a single host cell during such a process varies from virus to virus. For example, while a cell infected with the herpes virus produces only 50 to 100 new viruses on average, a cell infected with the poliovirus releases more than 1000 new viruses.

Types of viruses

Almost all viruses are host-specific, which means that a particular virus usually only infects a particular host organism. Depending on which organism is involved, a distinction is made between these human viruses and an incredible number of other viruses, which is why only the most important ones can be mentioned here. Most viruses cause a specific disease in humans.

(Bacterio-)phages = viruses that exclusively attack bacteria
Plant phytoviruses that only infect plants,
Animal viruses/animal viruses that only infect animals and
Human/human viruses that infect us humans.

Known DNA Viruses

The most important human pathogens belong to the DNA viruses: 1. the herpes viruses, in which a large number of subgroups are distinguished once again.Herpes viruses include the human herpes virus 1 and 2, which are responsible for the commonly known herpes, which manifests itself as vesicles, pain and/or itching and is usually manifested on the lips (herpes labialis, especially HHV 1) or in the genital area (herpes genitalis, especially HHV 2). The HHV 6 is responsible for the so-called 3-day fever. A rather rare herpes virus is HHV 8, as it only really causes infection in people with a weak immune system (for example, HIV-infected people), which leads to a certain type of cancer, Kaposi’s sarcoma.

2 The group of pox viruses includes both the triggers of harmless warts and the viruses that cause the dangerous pox. 3. the hepatitis B virus causes inflammation of the liver. 4. there are various different types of human papilloma viruses (HPV), which also lead to different clinical pictures.

While most (e.g. types 6 and 11) are relatively harmless, some (e.g. types 16 and 18) can cause cancer of the cervix (cervical cancer). 5. adenoviruses are often the cause of diarrhoea or colds with a rhinitis.

The Epstein-Barr-Virus (EBV), which causes Pfeiffer’s glandular fever (also: mononucleosis or “kissing disease”), also belongs to the herpes viruses
Varicella zoster virus (VZV), which leads to chickenpox in the case of initial infection and to shingles (herpes zoster) in the case of secondary infection.
Cytomegalovirus (CMV), which is particularly feared by pregnant women, as it can be life-threatening for unborn children.