Microorganisms、too embarrassed to ask others about！（Part 4）

4. what is a virus?

You are probably familiar with the term "computer virus". They say your computer can be infected when you access a suspicious site on the Internet. A computer virus is a program, not a living organism, of course. When that program invades your PC, it causes various troubles. In other words, computer viruses cannot do anything by themselves, but once they invade a computer, they start working like a living creature.
Viruses are similar to computer viruses in their behavior. The body of a virus is genetic information, or nucleic acid (DNA or RNA), that is the body of a virus is the nucleic acid, a chemical substance itself. Therefore, viruses do not have cells. The nucleic acid is surrounded by proteins, but it is still a chemical substance. As proof, viruses can be crystallized. A virus is a chemical substance, yet once it enters the cell of another organism, it can use the cell to increase itself. The virus multiplies itself in another cell and then destroys the cell when it breaks through and pops out. That is a viral disease.

When we think of viruses, we inevitably think of pathogens because of the worldwide pandemic of novel coronavirus infection (COVID-19), but not all viruses are pathogenic. There are approximately 30,000 known virus species, of which only 650 or so are said to be infectious. Viruses are only genetic material. They cannot multiply alone. To multiply, they need another living cell. This can be a human, animal, plant, fish, insect, or anything else. Some viruses attach themselves to bacteria. These are called bacteriophages. In short, a virus is an entity that survives thanks to living cells other than itself. And in general, they basically have a specific target to attach themselves to. In the case of ordinary meat available in supermarkets, the cells are dead and the virus cannot exploit them, so it does not spoil the meat as bacteria do.　However, viruses attached to meat do not multiply, but live for some time on the meat. Therefore, eating meat that has not been thoroughly overheated can lead to infection with viral diseases, such as food poisoning, hepatitis A, hepatitis E, etc.