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Viral disease. 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. [2]
The fourth step in the viral cycle is replication, which is defined by the rapid production of the viral genome. How a virus undergoes replication relies on the type of genetic material the virus possesses. Based on their genetic material, viruses will hijack the corresponding cellular machinery for said genetic material.
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.
Pathogenesis is a qualitative description of the process by which an initial infection causes disease. [2] Viral disease is the sum of the effects of viral replication on the host and the host's subsequent immune response against the virus. [3] Viruses are able to initiate infection, disperse throughout the body, and replicate due to specific ...
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 the infected host cell. But unlike simpler infectious agents ...
The term pathogen came into use in the 1880s. [2][3] Typically, the term pathogen is used to describe an infectious microorganism or agent, such as a virus, bacterium, protozoan, prion, viroid, or fungus. [4][5][6] Small animals, such as helminths and insects, can also cause or transmit disease. However, these animals are usually referred to as ...
Viral shedding. Viral shedding is the expulsion and release of virus progeny following successful reproduction during a host cell infection. Once replication has been completed and the host cell is exhausted of all resources in making viral progeny, the viruses may begin to leave the cell by several methods. [1]
Respiratory syncytial virus (RSV), [a] also called human respiratory syncytial virus (hRSV) and human orthopneumovirus, is a contagious virus that causes infections of the respiratory tract. It is a negative-sense, single-stranded RNA virus. [2] Its name is derived from the large cells known as syncytia that form when infected cells fuse. [2] [3]