What is a virus? Discover the world of viruses
Viruses are the most abundant biological entities on Earth. At the same time, they are also the smallest—just one drop of seawater contains more than 10 million viruses.
What is a virus?
A virus is not a living organism like bacteria or fungi. It is simply a package of genetic material (DNA or RNA) enclosed in a protein shell. Some viruses also have an additional membrane, referred to as an envelope. What makes viruses unique is their inability to reproduce independently—they always require a host, such as a bacterium, plant, or animal, to replicate.
How does a virus work?
Viruses have a fascinating survival strategy. They invade a host cell and hijack its machinery to create hundreds or even thousands of copies of themselves. Eventually, the host cell bursts open, releasing the newly produced viruses to infect other cells.
Living entity or lifeless particle?
Unlike other microbes, such as bacteria, viruses do not fit into the tree of life. They are not made of cells and lack their own metabolism. For this reason, many scientists consider viruses to be "non-living." However, viruses do contain genetic material, just like all living organisms, and they are subject to evolution. This places them in a unique position within biology.
Viruses: good or bad?
Although viruses are often associated with diseases, they are not all harmful. Some viruses, such as bacteriophages (or phages), exclusively infect bacteria. These viruses play an important role in controlling harmful bacterial populations. Phages are particularly effective because bacteria cannot develop permanent resistance to them, resulting in a continuous evolutionary arms race between bacteria and phages.
Viruses in our daily lives
Everyone encounters viruses at some point. The common cold, for instance, is caused by rhinoviruses, while the flu is caused by influenza viruses. Some viruses, like HIV or the smallpox virus, can have severe consequences, but the majority of viruses in our daily lives go unnoticed.
Understanding viruses
Viruses are fascinating biological entities that can be both harmful and beneficial. While they can cause diseases, they also play a vital role in nature, such as by keeping harmful bacteria in check. By learning more about viruses, we can better manage their effects and even harness them for positive purposes.