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Viral evolution is a subfield of evolutionary biology and virology 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).
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]
LUCA might have been the ancestor to some viruses, as it might have had at least two descendants: LUCELLA, the Last Universal Cellular Ancestor, the ancestor to all cells, and the archaic virocell ancestor, the ancestor to large-to-medium-sized DNA viruses. [77] Viruses might have evolved before LUCA but after the First universal common ...
Most virus species have virions too small to be seen with an optical microscope and are one-hundredth the size of most bacteria. The origins of viruses in the evolutionary history of life are still unclear. Some viruses may have evolved from plasmids, which are pieces of DNA that can move between cells. Other viruses may have evolved from bacteria.
Over the millennia, pandemics that have killed millions of people have been caused by pathogens such as viruses, bacteria and fungi that crossed over to people from animals.
Many human diseases are not static phenomena, but capable of evolution. Viruses, bacteria, fungi and cancers evolve to be resistant to host immune defences, as well as to pharmaceutical drugs. [245] [246] [247] These same problems occur in agriculture with pesticide [248] and herbicide [249] resistance.
A likely reservoir for viruses with pandemic-level potential is animals, and as humans encroach further on animals’s habitats through deforestation, there will be more opportunities for animal ...
Diverse viruses colonize the human skin and differ by skin site. [27] This skin virome includes human viruses (i.e. human papillomavirus) and bacteriophages (bacterial viruses) that infect commensal skin bacteria such as Staphylococci. [28] Virus communities differ by moisture levels and degree of protection from the external environment. [27]