Virus - Wikipedia
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. [1] Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. [2] [3] Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity.
Introduction to viruses - Wikipedia
A virus is a tiny infectious agent that reproduces inside the cells of living hosts. When infected, the host cell is forced to rapidly produce thousands of identical copies of the original virus. Unlike most living things, viruses do not have cells that divide; new viruses assemble in …
Viral disease - Wikipedia
A viral disease (or viral infection) occurs when an organism's body is invaded by pathogenic viruses, and infectious virus particles (virions) attach to and enter susceptible cells. [ 1 ] Examples are the common cold , gastroenteritis and pneumonia .
Virus - Simple English Wikipedia, the free encyclopedia
A virus is a tiny parasite. [1] Virology is the study of viruses. Viruses can only be seen under an electron microscope. Viruses are not free-living: they can only be parasites. They always reproduce inside other living things. All viruses infect living organisms, and may cause disease. The virus make copies of itself inside
Coronavirus - Wikipedia
The virus was then known as infectious bronchitis virus (IBV). Charles D. Hudson and Fred Robert Beaudette cultivated the virus for the first time in 1937. [ 18 ] The specimen came to be known as the Beaudette strain.
Virus | Definition, Structure, & Facts | Britannica
4 天之前 · Virus, infectious agent of small size and simple composition that can multiply only in living cells of animals, plants, or bacteria. Viruses possess unique infective properties and thus often cause disease in host organisms. Learn about the history, types, and features of viruses.
SARS-CoV-2 - Wikipedia
The virus is airborne and primarily spreads between people through close contact and via aerosols and respiratory droplets that are exhaled when talking, breathing, or otherwise exhaling, as well as those produced from coughs and sneezes.
Viruses: Definition, Types, Characteristics & Facts - Cleveland Clinic
A virus is a small piece of genetic information in a “carrying case” — a protective coating called a capsid. Viruses aren’t made up of cells, so they don’t have all the equipment that cells do to make more copies of themselves.
Types of Influenza Viruses | Influenza (Flu) | CDC
2024年9月18日 · Influenza virus basics. Influenza A viruses are the only influenza viruses known to cause flu pandemics (i.e., global epidemics of flu disease). A pandemic can occur when a new and different influenza A virus emerges that infects people, has the ability to spread efficiently among people, and against which people have little or no immunity.
COVID-19 - Wikipedia
Coronavirus disease 2019 (COVID-19) is a contagious disease caused by the coronavirus SARS-CoV-2.The disease spread worldwide, resulting in the COVID-19 pandemic.. The symptoms of COVID‑19 are variable but often include fever, [7] fatigue, cough, breathing difficulties, loss of smell, and loss of taste. [8] [9] [10] Symptoms may begin one to fourteen days after exposure …