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In the 20th century many diseases both old and new were found to be caused by viruses. There were epidemics of poliomyelitis that were only controlled following the development of a vaccine in the 1950s. HIV is one of the most pathogenic new viruses to have emerged in centuries. Although scientific interest in them arose because of the diseases ...
Viruses were expected to be small, but the range of sizes came as a surprise. Some were only a little smaller than the smallest known bacteria, and the smaller viruses were of similar sizes to complex organic molecules. [14] In 1935, Wendell Stanley examined the tobacco mosaic virus and found it was mostly made of protein. [15]
The invention of the electron microscope in 1931 brought the first images of viruses. [6] In 1935, American biochemist and virologist Wendell Meredith Stanley examined the tobacco mosaic virus (TMV) and found it to be mainly made from protein. [7] A short time later, this virus was shown to be made from protein and RNA. [8]
The so-called "hepatoencephalitis group of murine viruses" [20] were grouped into a single species named Mouse hepatitis virus, as approved in 1971. The species was merged with Rat coronavirus (discovered in 1970 [ 23 ] ) and Puffinosis coronavirus (discovered in 1982 [ 59 ] ) as Murine coronavirus in 2009.
Viral evolution is a subfield of evolutionary biology and virology that is specifically concerned with the evolution of viruses. [1] [2] Viruses have short generation times, and many—in particular RNA viruses—have relatively high mutation rates (on the order of one point mutation or more per genome per round of replication).
Gamma phage, an example of virus particles (visualised by electron microscopy) Virology is the scientific study of biological viruses.It is a subfield of microbiology that focuses on their detection, structure, classification and evolution, their methods of infection and exploitation of host cells for reproduction, their interaction with host organism physiology and immunity, the diseases they ...
Western Hemisphere populations were ravaged mostly by smallpox, but also typhus, measles, influenza, bubonic plague, cholera, malaria, tuberculosis, mumps, yellow fever, and pertussis. The lack of written records in many places and the destruction of many native societies by disease, war, and colonization make estimates uncertain.
[6] [7] The viral eukaryogenesis hypothesis points to the cell cycle of eukaryotes, particularly sex and meiosis, as evidence. [6] Little is known about the origins of DNA or reproduction in prokaryotic or eukaryotic cells. It is thus possible that viruses were involved in the creation of Earth's first cells. [8]