What Are the Types of Viruses?
What Are the Types of Viruses?
A virus is a viral agent which cannot reproduce itself within a host cell. Viruses may infect a number of living organisms, such as plants, bacteria, and even animals. Viruses have a simple structure, and are so small that even a microscopic microscope is required to view them. The virus particles can be viewed by a trained eye in a lab, with or without the addition of additional instruments. Some viruses cause only minor symptoms in their hosts, while other viruses can cause much more serious problems. It’s important to recognize a harmless virus from a dangerous one when you’re dealing with health issues caused by viruses.
Because viruses are genetic, the majority of their DNA remains exactly the same throughout their life cycle, or reproduction. This means that once a virus invades a host cell, it uses several genes from various ancestors to make repeat copies of itself. However, the spread of these genes is dependent on the mutation of DNA between the invading bacteria and the host’s immune system.
HIV, or Human Immunodeficiency Virus, is the most common virus in the world. This retrovirus attacks the immune system of the human body and destroys important DNA elements. HIV usually attaches itself to a cellular receptor on the surface of the cell and inserts its genetic RNA into the target cell’s genome. When the RNA acts on the target cell, it creates a genetic change which alters the protein makeup of that cell. The result is often a fatal illness called AIDS.
Some viruses have the ability to adopt the genetic mechanism of another, making it extremely hard to stop their spread. One such virus is the SARS virus, which is responsible for severe acute respiratory syndrome in those who catch the virus. There are various other viruses which may adopt a host cell’s genetic mechanism and cause disease. But viruses which are dependent on a host cell’s metabolism are by far the easiest to stop, as they tend to just replicate themselves and thus prevent the host cell from responding.
Viruses which rely on a host cell’s metabolism to reproduce tend to invade and attack multiple cells at once. For instance, enteroviruses (or anthrax viruses) can infect numerous cells simultaneously, while rotaviruses only infect one type of cell at a time. Thus, by the time the virus has transmitted to other locations, all the infected cells of the original organism have been destroyed. Some viruses may even divide themselves and spread to other parts of the body. Examples of this include herpes viruses, Epstein-Barr virus and cytomegalo virus.
When these types of viruses are spread to other locations, they tend to become resistant to the strain of the virus which initially caused the infection. Thus, they are less infectious than strains which were initially airborne. The most common way that viruses spread from one person to another is through physical contact. However, the most important way is through sexual contact, because that is how most respiratory viral infections are transmitted between partners.