A virus is an agent that causes infections and diseases.
Further Explanation
Viruses are microscopic parasites that infect cells of biological organisms. Viruses are obligate parasites, this is because viruses can only reproduce in living material by invading and utilizing the cells of living things because viruses do not have cellular equipment to reproduce themselves.
The term virus usually refers to particles that infect eukaryote cells (multicellular organisms and many types of single-cell organisms), while the term bacteriophage or phage is used for types that attack types of prokaryotic cells (bacteria and other organisms that do not cell nucleated).
The virus has been infecting since the days before Christ, this is evidenced by the existence of several discoveries, namely reports of virus infections in hieroglyphics in Memphis, the capital of ancient Egypt (1400 BC) which shows the existence of poliomyelitis. In addition, King Pharaoh Ramses V died in 1196 BC and is believed to have died of the smallpox virus.
In 1880, Louis Pasteur and Robert Koch put forward a "germ theory" namely that microorganisms are the cause of disease. At that time also the famous Koch Postulate which is very well known today, namely:
A disease agent must be present in every case of the disease
The agent must be isolated from the host and can be grown in vitro
When the muri agent culture is inoculated into susceptible healthy host cells, it can cause disease
The same agent can be taken and re-isolated from the infected host
Various kinds of viral infections
Acute infections are infections that last for a short time but can also be fatal.
Chronic infection is a prolonged viral infection so there is a risk of symptoms of the disease coming back.
Learn More
Viruses link
The infection by virus link
Details
Class: Middle School
Subject: Biology
Keywords: viruses, disease, infection
