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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]
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 ...
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.
Paleovirology is the study of viruses that existed in the past but are now extinct. In general, viruses cannot leave behind physical fossils, [1] therefore indirect evidence is used to reconstruct the past. For example, viruses can cause evolution of their hosts, and the signatures of that evolution can be found and interpreted in the present ...
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] Rosalind Franklin developed X-ray crystallographic pictures and determined the full structure of TMV in 1955. [9]
The virus travels in vomit and diarrhea. It spreads by direct contact with someone who has norovirus, or by touching contaminated surfaces and then putting your fingers in your mouth. Contaminated ...
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.
The Ebola virus devastated west Africa in 2014, claiming over 11,000 lives in Sierra Leone, Liberia and Guinea. ... Case fatality rates have varied from 25% to 90% in past ... There were no drugs ...